Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2019	Apr. 30, 2019
Document And Entity Information [Abstract]
Entity Registrant Name	Willis Towers Watson Plc.
Entity Central Index Key	0001140536
Trading Symbol	WLTW
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		129,236,178

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Revenue	$ 2,312	$ 2,292
Costs of providing services
Salaries and benefits	1,348	1,377
Other operating expenses	418	423
Depreciation	54	49
Amortization	127	141
Transaction and integration expenses	6	43
Total costs of providing services	1,953	2,033
Income from operations	359	259
Interest expense	(54)	(51)
Other income, net	55	56
INCOME FROM OPERATIONS BEFORE INCOME TAXES	360	264
Provision for income taxes	(67)	(43)
NET INCOME	293	221
Income attributable to non-controlling interests	(6)	(6)
NET INCOME ATTRIBUTABLE TO WILLIS TOWERS WATSON	$ 287	$ 215
EARNINGS PER SHARE
Basic earnings per share	$ 2.21	$ 1.62
Diluted earnings per share	$ 2.20	$ 1.61
Comprehensive income before non-controlling interests	$ 315	$ 305
Comprehensive income attributable to non-controlling interests	(5)	(7)
Comprehensive income attributable to Willis Towers Watson	$ 310	$ 298

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
ASSETS
Cash and cash equivalents	$ 992	$ 1,033
Fiduciary assets	15,129	12,604
Accounts receivable, net	2,490	2,379
Prepaid and other current assets	409	404
Total current assets	19,020	16,420
Fixed assets, net	957	942
Goodwill	10,456	10,465
Other intangible assets, net	3,187	3,318
Right-of-use assets	946
Pension benefits assets	833	773
Other non-current assets	494	467
Total non-current assets	16,873	15,965
TOTAL ASSETS	35,893	32,385
LIABILITIES AND EQUITY
Fiduciary liabilities	15,129	12,604
Deferred revenue and accrued expenses	1,240	1,647
Current debt	187	186
Current lease liabilities	158
Other current liabilities	940	864
Total current liabilities	17,654	15,301
Long-term debt	4,518	4,389
Liability for pension benefits	1,135	1,170
Deferred tax liabilities	544	559
Provision for liabilities	543	540
Long-term lease liabilities	961
Other non-current liabilities	296	429
Total non-current liabilities	7,997	7,087
TOTAL LIABILITIES	25,651	22,388
COMMITMENTS AND CONTINGENCIES
REDEEMABLE NON-CONTROLLING INTEREST	28	26
EQUITY
Additional paid-in capital	10,630	10,615
Retained earnings	1,439	1,201
Accumulated other comprehensive loss, net of tax	(1,974)	(1,961)
Treasury shares, at cost, 17,519 shares in 2019 and 2018, and 40,000 shares, €1 nominal value, in 2019 and 2018	(3)	(3)
Total Willis Towers Watson shareholders’ equity	10,092	9,852
Non-controlling interests	122	119
Total equity	10,214	9,971
TOTAL LIABILITIES AND EQUITY	$ 35,893	$ 32,385

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical)	Mar. 31, 2019 $ / shares shares	Mar. 31, 2019 € / shares shares	Dec. 31, 2018 $ / shares shares	Dec. 31, 2018 € / shares shares
Preference shares, nominal value (USD per share) \| $ / shares	$ 0.000115		$ 0.000115
Preference shares, shares authorized	1,000,000,000	1,000,000,000	1,000,000,000	1,000,000,000
Preference shares, shares issued	0	0	0	0
Ordinary shares, $0.000304635 nominal value [Member]
Ordinary shares, nominal value (euro per share) \| $ / shares	$ 0.000304635		$ 0.000304635
Ordinary shares, shares authorized	1,510,003,775	1,510,003,775	1,510,003,775	1,510,003,775
Ordinary shares, shares issued	129,211,111	129,211,111	128,921,530	128,921,530
Ordinary shares, shares outstanding	129,211,111	129,211,111	128,921,530	128,921,530
Treasury shares	17,519	17,519	17,519	17,519
Ordinary shares, €1 nominal value [Member]
Ordinary shares, nominal value (euro per share) \| € / shares		€ 1		€ 1
Ordinary shares, shares authorized	40,000	40,000	40,000	40,000
Ordinary shares, shares issued	40,000	40,000	40,000	40,000
Treasury shares	40,000	40,000	40,000	40,000

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
CASH FLOWS (USED IN)/FROM OPERATING ACTIVITIES
NET INCOME	$ 293	$ 221
Adjustments to reconcile net income to total net cash from operating activities:
Depreciation	54	51
Amortization	127	141
Non-cash lease expense	36	0
Net periodic benefit of defined benefit pension plans	(32)	(61)
Provision for doubtful receivables from clients	8	7
Benefit from deferred income taxes	(28)	(26)
Share-based compensation	10	3
Net loss on disposal of operations	0	9
Non-cash foreign exchange loss	8	17
Other, net	4	(3)
Changes in operating assets and liabilities, net of effects from purchase of subsidiaries:
Accounts receivable	(121)	(43)
Fiduciary assets	(2,490)	(1,326)
Fiduciary liabilities	2,490	1,326
Other assets	(37)	46
Other liabilities	(379)	(393)
Provisions	10	49
Net cash (used in)/from operating activities	(47)	18
CASH FLOWS USED IN INVESTING ACTIVITIES
Additions to fixed assets and software for internal use	(57)	(65)
Capitalized software costs	(17)	(13)
Acquisitions of operations, net of cash acquired	(1)	(5)
Net proceeds from sale of operations	0	4
Net cash used in investing activities	(75)	(79)
CASH FLOWS FROM/(USED IN) FINANCING ACTIVITIES
Net borrowings on revolving credit facility	138	61
Repayments of debt	(1)	(21)
Proceeds from issuance of shares	22	11
Cash paid for employee taxes on withholding shares	0	(7)
Dividends paid	(77)	(68)
Net cash from/(used in) financing activities	82	(24)
DECREASE IN CASH AND CASH EQUIVALENTS	(40)	(85)
Effect of exchange rate changes on cash and cash equivalents	(1)	9
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	1,033	1,030
CASH AND CASH EQUIVALENTS, END OF PERIOD	$ 992	$ 954

Condensed Consolidated Statements of Changes in Equity (Unaudited) - USD ($)
shares in Thousands, $ in Millions

Total

Shares outstanding [Member]

Ordinary shares and APIC [Member]

Retained earnings [Member]

Treasury shares [Member]

AOCL [Member]

^[1]

Total WTW shareholders’ equity [Member]

Non-controlling interests [Member]

Redeemable noncontrolling interests [Member]

Equity, beginning balance at Dec. 31, 2017

$ 10,249

$ 10,538

$ 1,104

$ (3)

$ (1,513)

$ 10,126

$ 123

Equity, beginning balance (in shares) at Dec. 31, 2017

132,140

Temporary equity, beginning balance at Dec. 31, 2017

^[2]

$ 28

Adoption of New Pronouncement (Accounting Standards Update 2014-09 [Member]) at Dec. 31, 2017

317

Increase (Decrease) in Stockholders' Equity [Roll Forward]

Net income

221

215

Net income, total

221

Dividends declared

(79)

Other comprehensive income/(loss)

Other comprehensive income, total

Issuance of shares under employee stock compensation plans

Issue of shares under employee stock compensation plans (in shares)

277

Share-based compensation and net settlements

Foreign currency translation

(4)

Equity, ending balance at Mar. 31, 2018

10,802

10,548

1,557

(3)

(1,430)

10,672

130

Equity, ending balance (in shares) at Mar. 31, 2018

132,417

Temporary equity, ending balance at Mar. 31, 2018

^[2]

Equity, beginning balance at Dec. 31, 2018

9,971

10,615

1,201

(3)

(1,961)

9,852

119

Equity, beginning balance (in shares) at Dec. 31, 2018

128,922

Temporary equity, beginning balance at Dec. 31, 2018

^[2]

Adoption of New Pronouncement (Accounting Standards Update 2018-02 [Member]) at Dec. 31, 2018

(36)

Increase (Decrease) in Stockholders' Equity [Roll Forward]

Net income

291

287

Net income, redeemable

^[2]

Net income, total

293

Dividends declared

(85)

Other comprehensive income/(loss)

(1)

Other comprehensive income, total

Issuance of shares under employee stock compensation plans

Issue of shares under employee stock compensation plans (in shares)

289

Share-based compensation and net settlements

(7)

Equity, ending balance at Mar. 31, 2019

$ 10,214

$ 10,630

$ 1,439

$ (3)

$ (1,974)

$ 10,092

$ 122

Equity, ending balance (in shares) at Mar. 31, 2019

129,211

Temporary equity, ending balance at Mar. 31, 2019

^[2]

$ 28

[1]	Accumulated other comprehensive loss, net of tax (‘AOCL’).
[2]	The non-controlling interest is related to Max Matthiessen Holding AB.

Nature of Operations

3 Months Ended

Mar. 31, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Nature of Operations

Note 1 — Nature of Operations

Willis Towers Watson plc is a leading global advisory, broking and solutions company that helps clients around the world turn risk into a path for growth. The Company has more than 43,000 employees servicing clients in more than 140 countries.

We offer our clients a broad range of services to help them identify and control their risks, and to enhance business performance by improving their ability to attract, retain and engage a talented workforce. Our risk control services range from strategic risk consulting (including providing actuarial analysis), to a variety of due diligence services, to the provision of practical on-site risk control services (such as health and safety or property loss control consulting), as well as analytical and advisory services (such as hazard modeling and reinsurance optimization studies). We assist clients in planning how to manage incidents or crises when they occur. These services include contingency planning, security audits and product tampering plans. We help our clients enhance their business performance by delivering consulting services, technology and solutions that help them anticipate, identify and capitalize on emerging opportunities in human capital management, as well as offer investment advice to help them develop disciplined and efficient strategies to meet their investment goals.

As an insurance broker, we act as an intermediary between our clients and insurance carriers by advising our clients on their risk management requirements, helping them to determine the best means of managing risk and negotiating and placing insurance with insurance carriers through our global distribution network. We operate a private Medicare exchange in the U.S. Through this exchange and those for active employees, we help our clients move to a more sustainable economic model by capping and controlling the costs associated with healthcare benefits. We are not an insurance company, and therefore we do not underwrite insurable risks for our own account.

We believe our broad perspective allows us to see the critical intersections between talent, assets and ideas - the dynamic formula that drives business performance.

Basis of Presentation and Recent Accounting Pronouncements

3 Months Ended

Mar. 31, 2019

Accounting Policies [Abstract]

Basis of Presentation and Recent Accounting Pronouncements

Note 2 — Basis of Presentation and Recent Accounting Pronouncements

Basis of Presentation

The accompanying unaudited quarterly condensed consolidated financial statements of Willis Towers Watson and our subsidiaries are presented in accordance with the rules and regulations of the SEC for quarterly reports on Form 10-Q and therefore do not include all of the information and footnotes required by U.S. GAAP. In the opinion of management, these condensed consolidated financial statements reflect all adjustments, consisting of normal recurring adjustments, which are necessary for a fair presentation of the condensed consolidated financial statements and results for the interim periods. All intercompany accounts and transactions have been eliminated in consolidation. The condensed consolidated financial statements should be read together with the Company’s Annual Report on Form 10-K, filed with the SEC on February 27, 2019, and may be accessed via EDGAR on the SEC’s web site at www.sec.gov.

The results of operations for the three months ended March 31, 2019 are not necessarily indicative of the results that can be expected for the entire year. The Company experiences seasonal fluctuations of its revenue. Revenue is typically higher during the Company’s first and fourth quarters due to the timing of broking-related activities. The results reflect certain estimates and assumptions made by management, including those estimates used in calculating acquisition consideration and fair value of tangible and intangible assets and liabilities, professional liability claims, estimated bonuses, valuation of billed and unbilled receivables, and anticipated tax liabilities that affect the amounts reported in the condensed consolidated financial statements and related notes.

Recent Accounting Pronouncements

Not Yet Adopted

In January 2017, the FASB issued ASU No. 2017-04, Simplifying the Test for Goodwill Impairment, which simplifies the subsequent measurement of goodwill by eliminating Step 2 from the goodwill impairment test. In computing the implied fair value of goodwill under Step 2, current U.S. GAAP requires the performance of procedures to determine the fair value at the impairment testing date of assets and liabilities (including unrecognized assets and liabilities) following the procedure that would be required in determining the fair value of assets acquired and liabilities assumed in a business combination. Instead, the amendments under this ASU require the goodwill impairment test to be performed by comparing the fair value of a reporting unit with its carrying amount. An impairment charge would be recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. The ASU becomes effective for the Company on January 1, 2020, at which time the Company will adopt it, although earlier adoption is permitted. The amendments in this ASU should be applied on a prospective basis. The Company does not expect an immediate impact to its condensed consolidated

financial statements upon adopting this ASU since the most recent Step 1 goodwill impairment test resulted in fair values in excess of carrying values for all reporting units at October 1, 2018.

In August 2018, the FASB issued two ASU’s as part of its disclosure framework project. The focus of this project is to improve the effectiveness of disclosures in the notes to the financial statements by facilitating clear communication of the information required by U.S. GAAP that is most important to users of an entity’s financial statements. Both of these ASU’s remove certain disclosure requirements and add or modify other requirements. The two ASU’s are as follows:

•

ASU No. 2018-13, Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement – effective for the Company on January 1, 2020, although early adoption is permitted immediately. Additionally, companies are permitted to immediately adopt the removal or modifications of disclosures as provided in this ASU, and adopt the additional disclosures on the effective date of the ASU. Certain provisions of the ASU must be adopted retrospectively, while others must be adopted prospectively. The Company is still assessing when and how it will adopt this ASU, but does not expect there to be a material impact to the notes to the condensed consolidated financial statements.

•

ASU No. 2018-14, Disclosure Framework—Changes to the Disclosure Requirements for Defined Benefit Plans – this ASU will impact certain 10-K disclosures and will be effective for the Company for its 2020 Annual Report on Form 10-K. Early adoption is permitted and must be applied on a retrospective basis. The Company is still assessing when it will adopt this ASU, but does not expect there to be a material impact to the notes to the condensed consolidated financial statements.

Adopted

In February 2016, the FASB issued ASU No. 2016-02, Leases (‘ASU No. 2016-02’), which requires a lessee to recognize in the statement of financial position a liability to make lease payments (the lease liability) and a right-of-use asset representing its right to use the underlying asset for the lease term. Additional ASUs have since been issued which provide amended and additional guidance for the implementation of ASU No. 2016-02. All related guidance has been codified into, and is now known as, ASC 842, Leases (‘ASC 842’). ASC 842 became effective, and was adopted by the Company, on January 1, 2019. See below and Note 12 – Leases, for a full description of the Company’s impact from adoption, adoption elections made and the newly-required disclosures.

In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging: Targeted Improvements to Accounting for Hedging Activities, which provides amendments under six specific objectives to better align risk management activities and financial reporting, and to simplify disclosure, presentation, hedging and the testing and measurement of ineffectiveness. The ASU became effective for, and was adopted by, the Company on January 1, 2019. This ASU did not have a material impact on our condensed consolidated financial statements.

In February 2018, the FASB issued ASU No. 2018-02, Income Statement - Reporting Comprehensive Income: Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (‘ASU 2018-02’), which allows for a reclassification from accumulated other comprehensive income/(loss) to retained earnings for ‘stranded’ tax effects (those tax effects of items within accumulated other comprehensive income resulting from the historical corporate income tax rate reduction) resulting from U.S. Tax Reform. The amendments within this ASU also require certain disclosures about stranded tax effects. The ASU became effective for, and was adopted by, the Company on January 1, 2019, at which time it recorded a reclassification between AOCL and retained earnings of $36 million. The reclassification of $36 million from AOCL includes the effect of the change in the U.S. federal corporate tax rate, however it does not include other income tax effects of U.S. Tax Reform. The stranded tax effect primarily relates to defined pension and post-retirement benefits. The Company’s policy is to use the portfolio approach for releasing disproportionate income tax effects from AOCL.

Changes to Accounting Policies

As a result of the adoption of ASC 842 on January 1, 2019, we have updated our accounting policies for leases. These policies govern the recognition and accounting for leases in tandem with the Company’s option to elect certain practical expedients offered by ASC 842. These policies are consistent with the modified retrospective approach guidance and with those practical expedients offered by ASC 842 that we have elected to apply. Our lease policies for 2018 and prior reporting periods are reflected in the notes to our annual consolidated financial statements as filed on February 27, 2019, in our Annual Report on Form 10-K.

Leases

As an advisory, broking and solutions company providing services to clients in more than 140 countries, we enter into lease agreements from time to time, primarily for the use of real estate for our office space. We determine if an arrangement is a lease at the inception of the contract, and the nature of our operations is such that it is generally clear whether an arrangement contains a lease and what underlying asset is being leased. The majority of the leases into which we enter are operating leases. Upon entering into leases, we obtain the right to control the use of an identified space for a lease term and recognize these right-of-use (‘ROU’) assets on our condensed consolidated balance sheets with corresponding lease liabilities reflecting our obligation to make the related lease payments. ROU assets are amortized over the term of the lease.

Our real estate leases are generally long-term in nature, with terms that typically range from 5 to 15 years. Our most significant lease supports our London market operations with a lease term through 2032. Our real estate leases often contain options to renew the lease, either through exercise of the option or through automatic renewal. Additionally, certain leases have options to cancel the lease with appropriate notice to the landlord prior to the end of the stated lease term. As we enter into new leases after the adoption of ASC 842, we will consider these options as we assess lease terms in our recognized ROU assets and lease liabilities. If we are reasonably certain to exercise an option to renew a lease, we include this period in our lease term. To the extent that we have the option to cancel a lease, we recognize our ROU assets and lease liabilities using the term that would result from using this earlier date. If a significant penalty is required to cancel the lease at an earlier date, we assess our lease term as ending at the point when no significant penalty would be due.

In addition to payments for previously-agreed base rent, many of our lease agreements are subject to variable and unknown future payments, typically in the form of common area maintenance charges (a non-lease component as defined by ASC 842) or real estate taxes. These variable payments are excluded from our lease liabilities and ROU assets, and instead are recognized as lease expense within other operating expenses on the condensed consolidated statement of comprehensive income as the amounts are incurred. To the extent that we have agreed to fixed charges for common area maintenance or other non-lease components, or our base rent increases by an index or rate (most commonly an inflation rate), these amounts are included in the measurement of our lease liabilities and ROU assets. We have elected the practical expedient under ASC 842 which allows the lease and non-lease components to be combined in our measurement of lease liabilities and ROU assets.

From time to time we may enter into subleases if we are unable to cancel or fully occupy a space and are able to find an appropriate subtenant. However, entering subleases is not a primary objective of our business operations and these arrangements represent an immaterial amount of cash flows.

Because the discount rates implicit in our leases are generally not readily determinable, we are required to use judgment in the determination of the incremental borrowing rates to calculate the present values of our future lease payments. Since the majority of our debt is publicly-traded, our real estate function is centralized, and our treasury function is centralized and generally prohibits our subsidiaries from borrowing externally, we have determined it appropriate to use the Company’s consolidated unsecured borrowing rate, and adjust for collateralization in accordance with ASC 842. Using the resulting interest rate curves from publicly-traded debt at this collateralized borrowing rate, we select the interest rate at lease inception by reference to the lease term and lease currency. Over 90% of our leases are denominated in U.S. dollars, Pounds sterling or Euros.

Our leases generally do not subject us to restrictive covenants and contain no residual value guarantees.

Acquisitions

3 Months Ended

Mar. 31, 2019

Business Combinations [Abstract]

Acquisitions

Note 3 — Acquisitions

TRANZACT Acquisition

On March 30, 2019, the Company entered into an agreement to acquire TRANZACT, a U.S.-based provider of comprehensive, direct-to-consumer sales and marketing solutions for leading insurance carriers in the U.S. TRANZACT leverages digital, data and direct marketing solutions to deliver qualified leads, fully-provisioned sales and robust customer management systems to brands seeking to acquire and manage large numbers of consumers. Subject to certain adjustments, the consideration consists of $1.2 billion payable upon the close of the acquisition, of which $100 million is payable at our option in cash or ordinary shares of the Company. Additional contingent consideration in the form of a potential earn-out of up to $200 million is payable in either cash or in ordinary shares of the Company at our option in 2021 based on the achievement of certain financial targets. The Company has secured a term loan to finance the transaction (see Note 9 — Debt for further information). TRANZACT will operate as part of the Company’s Benefits Delivery and Administration segment. The transaction is expected to close during the third quarter of 2019.

Alston Gayler Acquisition

On December 21, 2018, the Company, through its majority-owned subsidiary, Miller, completed the transaction to acquire Alston Gayler, a U.K.-based insurance and reinsurance broker, for total consideration of $67 million. Cash consideration of $35 million was paid upon completion of the acquisition, with the remaining $32 million deferred consideration to be paid in equal installments on the first, second and third anniversaries of the date of acquisition.

The Company has preliminarily recognized $36 million of intangible assets, primarily arising from client relationships, and $24 million of goodwill. The purchase price allocation as of the acquisition date and our accounting for the related deferred tax assets and liabilities is not yet complete.

Revenue

3 Months Ended

Mar. 31, 2019

Revenue From Contract With Customer [Abstract]

Revenue

Note 4 — Revenue

Disaggregation of Revenue

The Company reports revenue by segment in Note 5 — Segment Information. The following table presents revenue by service offering and segment, as well as a reconciliation to total revenue for the three months ended March 31, 2019 and 2018. Along with reimbursable expenses and other, total revenue by service offering represents our revenue from customer contracts.

	Three Months Ended March 31,
	HCB				CRB				IRR				BDA				Corporate ⁽ⁱⁱ⁾				Total
	2019		2018		2019		2018		2019		2018		2019		2018		2019		2018		2019		2018
Broking	$	73	$	76	$	660	$	664	$	405	$	391	$	3	$	4	$	—	$	—	$	1,141	$	1,135
Consulting ⁽ⁱ⁾		580		577		31		44		114		117		—		—		3		3		728		741
Outsourced administration ⁽ⁱ⁾		123		132		27		23		2		—		132		118		—		—		284		273
Other ⁽ⁱ⁾		47		43		1		3		58		59		—		—		1		1		107		106
Total revenues by service offering		823		828		719		734		579		567		135		122		4		4		2,260		2,255
Reimbursable expenses and other ⁽ⁱⁱ⁾		14		14		—		—		2		2		3		2		7		1		26		19
Total revenue from customer contracts	$	837	$	842	$	719	$	734	$	581	$	569	$	138	$	124	$	11	$	5	$	2,286	$	2,274
Interest and other income ⁽ⁱⁱⁱ⁾		6		4		9		6		10		7		—		—		1		1		26		18
Total revenue	$	843	$	846	$	728	$	740	$	591	$	576	$	138	$	124	$	12	$	6	$	2,312	$	2,292

______________

(i)	Amounts presented for HCB Outsourced administration revenue include a correction of approximately $58 million of revenue that was previously classified as HCB Consulting revenue or HCB Other revenue in our quarterly report on Form 10-Q for the three months ended March 31, 2018.

(ii)	Reimbursable expenses and other, as well as Corporate revenue, are excluded from segment revenue, but included in total revenue on the condensed consolidated statements of comprehensive income.

(iii)

Interest and other income is included in segment revenue and total revenue, however it has been presented separately in the above tables because it does not arise directly from contracts with customers.

Individual revenue streams aggregating to approximately 5% of total revenue from customer contracts for the three months ended March 31, 2019 and 2018, respectively, have been included within the Other line in the tables above.

The following table presents revenue by the geography where our work is performed for the three months ended March 31, 2019 and 2018. The reconciliation to total revenue on our condensed consolidated statements of comprehensive income and to segment revenue is shown in the table above.

	Three Months Ended March 31,
	HCB				CRB				IRR				BDA				Corporate				Total
	2019		2018		2019		2018		2019		2018		2019		2018		2019		2018		2019		2018
North America	$	471	$	462	$	220	$	215	$	164	$	153	$	135	$	122	$	4	$	4	$	994	$	956
Great Britain		118		129		142		148		300		295		—		—		—		—		560		572
Western Europe		155		154		239		239		69		71		—		—		—		—		463		464
International		79		83		118		132		46		48		—		—		—		—		243		263
Total revenue by geography	$	823	$	828	$	719	$	734	$	579	$	567	$	135	$	122	$	4	$	4	$	2,260	$	2,255

Contract Balances

The Company reports accounts receivable, net on the condensed consolidated balance sheet, which includes billed and unbilled receivables and current contract assets. In addition to accounts receivable, net, the Company had the following non-current contract assets and deferred revenue balances at March 31, 2019 and December 31, 2018:

	March 31, 2019		December 31, 2018
Billed receivables, net of allowance for doubtful accounts of $44 million and $40 million	$	1,847	$	1,702
Unbilled receivables		396		356
Current contract assets		247		321
Accounts receivable, net	$	2,490	$	2,379
Non-current accounts receivable, net	$	17	$	20
Non-current contract assets	$	6	$	3
Deferred revenue	$	483	$	448

During the three months ended March 31, 2019, revenue of approximately $242 million was recognized that was reflected as deferred revenue at December 31, 2018.

During the three months ended March 31, 2019, the Company recognized no material revenue related to performance obligations satisfied in a prior period.

Performance Obligations

The Company has contracts for which performance obligations have not been satisfied as of March 31, 2019 or have been partially satisfied as of this date. The following table shows the expected timing for the satisfaction of the remaining performance obligations. This table does not include contract renewals nor variable consideration, which was excluded from the transaction prices in accordance with the guidance on constraining estimates of variable consideration.

In addition, in accordance with ASC 606, Revenue From Contracts With Customers (‘ASC 606’), the Company has elected not to disclose the remaining performance obligations when one or both of the following circumstances apply:

•

Performance obligations which are part of a contract that has an original expected duration of less than one year, and

•

Performance obligations satisfied in accordance with ASC 606-10-55-18 (‘right to invoice’).

		Remainder of 2019				2020				2021 onward				Total
Revenue expected to be recognized on contracts as of March 31, 2019		$	314			$	341			$	432			$	1,087

Since most of the Company’s contracts are cancellable with less than one year’s notice, and have no substantive penalty for cancellation, the majority of the Company’s remaining performance obligations as of March 31, 2019 have been excluded from the table above.

Segment Information

3 Months Ended

Mar. 31, 2019

Segment Reporting [Abstract]

Segment Information

Note 5 — Segment Information

Willis Towers Watson has four reportable operating segments or business areas:

•

Human Capital and Benefits (‘HCB’)

•

Corporate Risk and Broking (‘CRB’)

•

Investment, Risk and Reinsurance (‘IRR’)

•

Benefits Delivery and Administration (‘BDA’)

Willis Towers Watson’s chief operating decision maker is its chief executive officer. We determined that the operational data used by the chief operating decision maker is at the segment level. Management bases strategic goals and decisions on these segments and the data presented below is used to assess the adequacy of strategic decisions and the methods of achieving these strategies and related financial results. Management evaluates the performance of its segments and allocates resources to them based on net operating income on a pre-tax basis.

The Company experiences seasonal fluctuations of its revenue. Revenue is typically higher during the Company’s first and fourth quarters due primarily to the timing of broking-related activities.

The following table presents segment revenue and segment operating income for our reportable segments for the three months ended March 31, 2019 and 2018.

	Three Months Ended March 31,
	HCB				CRB				IRR				BDA						Total
	2019		2018		2019		2018		2019		2018		2019			2018			2019		2018
Segment revenue	$	829	$	832	$	728	$	740	$	589	$	574	$	135		$	122		$	2,281	$	2,268

Segment operating income/(loss)	$	204	$	193	$	127	$	125	$	252	$	261	$	(21	)	$	(32	)	$	562	$	547

The following table presents a reconciliation of the information reported by segment to the Company’s condensed consolidated statement of comprehensive income amounts reported for the three months ended March 31, 2019 and 2018.

	Three Months Ended March 31,
	2019			2018
Revenue:
Total segment revenue	$	2,281		$	2,268
Reimbursable expenses and other		31			24
Revenue	$	2,312		$	2,292

Total segment operating income	$	562		$	547
Amortization		(127	)		(141	)
Transaction and integration expenses		(6	)		(43	)
Unallocated, net ⁽ⁱ⁾		(70	)		(104	)
Income from operations		359			259
Interest expense		(54	)		(51	)
Other income, net		55			56
Income from operations before income taxes	$	360		$	264

(i)	Includes certain costs, primarily related to corporate functions which are not directly related to the segments, and certain differences between budgeted expenses determined at the beginning of the year and actual expenses that we report for U.S. GAAP purposes.

The Company does not currently provide asset information by reportable segment as it does not routinely evaluate the total asset position by segment.

Income Taxes

3 Months Ended

Mar. 31, 2019

Income Tax Disclosure [Abstract]

Income Taxes

Note 6 — Income Taxes

Provision for income taxes for the three months ended March 31, 2019 was $67 million compared to $43 million for the three months ended March 31, 2018. The effective tax rate was 18.8% for the three months ended March 31, 2019 and 16.3% for the three months ended March 31, 2018. These effective tax rates are calculated using extended values from our condensed consolidated statements of comprehensive income, and are therefore more precise tax rates than can be calculated from rounded values. The increase in the effective tax rate for the period ended March 31, 2019 compared to the period ended March 31, 2018 was primarily due to additional taxes on global intangible low-taxed income (GILTI).

In 2017, as a result of U.S. Tax Reform, we analyzed our global working capital and cash requirements and the potential tax liabilities attributable to a repatriation, and changed our assertion with respect to certain legacy Towers Watson subsidiaries. For those subsidiaries from which we were able to make a reasonable estimate of the tax effects of such repatriation, we recorded an estimate for foreign withholding and state income taxes. For all other subsidiaries, we continue to assert that the historical cumulative earnings have been reinvested indefinitely, and therefore do not provide deferred taxes on these amounts.

The Company records valuation allowances against net deferred tax assets based on whether it is more likely than not that the deferred tax assets will be realized. We have liabilities for uncertain tax positions under ASC 740 of $48 million, excluding interest and penalties. The Company believes the outcomes that are reasonably possible within the next 12 months may result in a reduction in the liability for uncertain tax positions of approximately $1 million to $3 million, excluding interest and penalties.

Goodwill and Other Intangible Assets

3 Months Ended

Mar. 31, 2019

Goodwill And Intangible Assets Disclosure [Abstract]

Goodwill and Other Intangible Assets

Note 7 — Goodwill and Other Intangible Assets

The components of goodwill are outlined below for the three months ended March 31, 2019:

	HCB			CRB			IRR		BDA		Total
Balance at December 31, 2018:
Goodwill, gross	$	4,300		$	2,308		$	1,792	$	2,557	$	10,957
Accumulated impairment losses		(130	)		(362	)		—		—		(492	)
Goodwill, net - December 31, 2018		4,170			1,946			1,792		2,557		10,465
Foreign exchange		(6	)		(7	)		4		—		(9	)
Balance at March 31, 2019:
Goodwill, gross		4,294			2,301			1,796		2,557		10,948
Accumulated impairment losses		(130	)		(362	)		—		—		(492	)
Goodwill, net - March 31, 2019	$	4,164		$	1,939		$	1,796	$	2,557	$	10,456

Other Intangible Assets

The following table reflects changes in the net carrying amounts of the components of finite-lived intangible assets for the three months ended March 31, 2019:

	Balance at December 31, 2018		Intangible assets acquired		Intangible assets disposed			ASC 842 reclassification ⁽ⁱ⁾			Amortization			Foreign exchange			Balance at March 31, 2019
Client relationships	$	1,986	$	3	$	(1	)	$	—		$	(82	)	$	3		$	1,909
Management contracts		48		—		—			—			(1	)		(2	)		45
Software		328		—		—			—			(32	)		2			298
Trademark and trade name		920		—		—			—			(11	)		—			909
Product		27		—		—			—			(1	)		—			26
Favorable agreements		9		—		—			(9	)		—			—			—
Total amortizable intangible assets	$	3,318	$	3	$	(1	)	$	(9	)	$	(127	)	$	3		$	3,187

__________________

(i) On January 1, 2019, in accordance with ASC 842, we reclassified our favorable lease agreement assets to right-of-use assets within our condensed consolidated balance sheet.

We recorded amortization related to our finite-lived intangible assets of $127 million for the three months ended March 31, 2019; for the three months ended March 31, 2018, we recorded amortization related to our finite-lived intangible assets, exclusive of the amortization of our favorable lease agreements, of $141 million.

Our acquired unfavorable lease agreement liabilities were $21 million at December 31, 2018 and are recorded in other non-current liabilities in the condensed consolidated balance sheet. On January 1, 2019, in accordance with ASC 842, we reclassified our unfavorable lease liabilities as a reduction to our right-of-use assets within our condensed consolidated balance sheet.

The following table reflects the carrying value of finite-lived intangible assets and liabilities at March 31, 2019 and December 31, 2018:

	March 31, 2019					December 31, 2018
	Gross carrying amount		Accumulated amortization			Gross carrying amount		Accumulated amortization
Client relationships	$	3,405	$	(1,496	)	$	3,401	$	(1,415	)
Management contracts		60		(15	)		63		(15	)
Software		754		(456	)		749		(421	)
Trademark and trade name		1,052		(143	)		1,052		(132	)
Product		36		(10	)		36		(9	)
Favorable agreements ⁽ⁱ⁾		—		—			14		(5	)
Other		2		(2	)		3		(3	)
Total finite-lived assets	$	5,309	$	(2,122	)	$	5,318	$	(2,000	)

Unfavorable agreements ⁽ⁱ⁾	$	—	$	—		$	34	$	(13	)
Total finite-lived intangible liabilities	$	—	$	—		$	34	$	(13	)

__________________

(i) On January 1, 2019, in accordance with ASC 842, we reclassified our favorable lease agreement assets and unfavorable lease agreement liabilities to right-of-use assets and as reductions to right-of-use assets, respectively, within our condensed consolidated balance sheet.

The weighted-average remaining life of amortizable intangible assets at March 31, 2019 was 13.8 years.

The table below reflects the future estimated amortization expense for amortizable intangible assets for the remainder of 2019 and for subsequent years:

	Amortization
Remainder of 2019	$	353
2020		424
2021		347
2022		288
2023		239
Thereafter		1,536
Total	$	3,187

Derivative Financial Instruments

3 Months Ended

Mar. 31, 2019

Derivative Instruments And Hedging Activities Disclosure [Abstract]

Derivative Financial Instruments

Note 8 — Derivative Financial Instruments

We are exposed to certain foreign currency risks. Where possible, we identify exposures in our business that can be offset internally. Where no natural offset is identified, we may choose to enter into various derivative transactions. These instruments have the effect of reducing our exposure to unfavorable changes in foreign currency rates. The Company’s board of directors reviews and approves policies for managing each of these risks as summarized below. Additional information regarding our derivative financial instruments can be found in Note 10 — Fair Value Measurements and Note 15 — Accumulated Other Comprehensive Loss.

Foreign Currency Risk

Certain non-U.S. subsidiaries receive revenue and incur expenses in currencies other than their functional currency, and as a result, the foreign subsidiary’s functional currency revenue will fluctuate as the currency rates change. Additionally, the forecast Pounds sterling expenses of our London brokerage market operations may exceed their Pounds sterling revenue, and they may also hold significant foreign currency asset or liability positions in the condensed consolidated balance sheet. To reduce such variability, we use foreign exchange contracts to hedge against this currency risk.

These derivatives were designated as hedging instruments and at March 31, 2019 and December 31, 2018 had total notional amounts of $414 million and $438 million, respectively, and had net fair value liabilities of $3 million and $15 million, respectively.

At March 31, 2019, the Company estimates, based on current exchange rates, there will be $2 million of net derivative losses on forward exchange rates reclassified from accumulated other comprehensive loss into earnings within the next twelve months as the forecast transactions affect earnings. At March 31, 2019, our longest outstanding maturity was 1.7 years.

The effects of the material derivative instruments that are designated as hedging instruments on the condensed consolidated statements of comprehensive income for the three months ended March 31, 2019 and 2018 are below. Amounts pertaining to the ineffective portion of hedging instruments and excluded from effectiveness testing were immaterial for the three months ended March 31, 2019 and 2018.

Three Months Ended March 31,	Gain recognized in OCI (effective element)
	2019		2018
Forward exchange contracts	$	8	$	15

Location of gain/(loss) reclassified from Accumulated OCL into income (effective element)	Gain/(loss) reclassified from Accumulated OCL into income (effective element)
	2019			2018
Revenue	$	1		$	—
Salaries and benefits		(5	)		—
Other income, net		—			(11	)
	$	(4	)	$	(11	)

We also enter into foreign currency transactions, primarily to hedge certain intercompany loans. These derivatives are not generally designated as hedging instruments, and at March 31, 2019 and December 31, 2018, we had notional amounts of $890 million and $909 million, respectively, and had a net fair value liability of $7 million and a net fair value asset of $3 million, respectively.

The effects of derivatives that have not been designated as hedging instruments on the condensed consolidated statements of comprehensive income for the three months ended March 31, 2019 and 2018 are as follows:

		Loss recognized in income
		Three Months Ended March 31,
Derivatives not designated as hedging instruments:	Location of loss recognized in income	2019			2018
Forward exchange contracts	Other income, net	$	(10	)	$	(5	)

Debt

3 Months Ended

Mar. 31, 2019

Debt Disclosure [Abstract]

Debt

Note 9 — Debt

Current debt consists of the following:

March 31,

2019

December 31,

2018

7.000% senior notes due 2019

187

186

Long-term debt consists of the following:

	March 31, 2019		December 31, 2018
Revolving $1.25 billion credit facility	$	269	$	130
5.750% senior notes due 2021		498		498
3.500% senior notes due 2021		448		448
2.125% senior notes due 2022⁽ⁱ⁾		604		615
4.625% senior notes due 2023		248		248
3.600% senior notes due 2024		646		645
4.400% senior notes due 2026		544		544
4.500% senior notes due 2028		595		595
6.125% senior notes due 2043		271		271
5.050% senior notes due 2048		395		395
	$	4,518	$	4,389

(i)	Notes issued in Euro (€540 million)

At March 31, 2019 and December 31, 2018, we were in compliance with all financial covenants.

One-Year Term Loan Commitment

As part of the pending acquisition of TRANZACT, the Company has secured financing of up to $1.1 billion in the form of a one-year unsecured term loan. Borrowing will occur in conjunction with the closing of the acquisition, which is expected during the third quarter of 2019.

Amounts outstanding under the term loan shall bear interest, at the option of the borrowers, at a rate equal to (a) LIBOR plus 0.75% to 1.375% for Eurocurrency Rate Loans or (b) the highest of (i) the Federal Funds Rate plus 0.5%, (ii) the ‘prime rate’ quoted by Bank of America, N.A., and (iii) LIBOR plus 1.00%, plus 0.00% to 0.375%, in each case, based upon the Company’s guaranteed senior-unsecured long-term debt rating. In addition, the Company will pay a commitment fee in an amount equal to 0.15% per annum on the undrawn portion of the commitments in respect of the term loan, which fee shall accrue from May 29, 2019 to, but excluding, the earlier to occur of the closing date of the acquisition or the termination of the term loan commitments.

The term loan is pre-payable in part or in full prior to the maturity date at the Company’s discretion. Covenants and events of default are substantively the same as in our existing revolving credit facility.

Fair Value Measurements

3 Months Ended

Mar. 31, 2019

Fair Value Disclosures [Abstract]

Fair Value Measurements

Note 10 — Fair Value Measurements

The Company has categorized its assets and liabilities that are measured at fair value on a recurring and non-recurring basis into a three-level fair value hierarchy, based on the reliability of the inputs used to determine fair value as follows:

•

Level 1: refers to fair values determined based on quoted market prices in active markets for identical assets;

•

Level 2: refers to fair values estimated using observable market-based inputs or unobservable inputs that are corroborated by market data; and

•

Level 3: includes fair values estimated using unobservable inputs that are not corroborated by market data.

The following methods and assumptions were used by the Company in estimating its fair value disclosure for financial instruments:

•

Available-for-sale securities are classified as Level 1 because we use quoted market prices in determining the fair value of these securities.

•

Market values for our derivative instruments have been used to determine the fair value of forward foreign exchange contracts based on estimated amounts the Company would receive or have to pay to terminate the agreements, taking into account observable information about the current foreign currency forward rates. Such financial instruments are classified as Level 2 in the fair value hierarchy.

•

Contingent consideration payable is classified as Level 3, and we estimate fair value based on the likelihood and timing of achieving the relevant milestones of each arrangement, applying a probability assessment to each of the potential outcomes, and discounting the probability-weighted payout. Typically, milestones are based on revenue or Earnings Before Interest, Tax, Depreciation and Amortization (‘EBITDA’) growth for the acquired business.

The following tables present our assets and liabilities measured at fair value on a recurring basis at March 31, 2019 and December 31, 2018:

		Fair Value Measurements on a Recurring Basis at March 31, 2019
	Balance Sheet Location	Level 1		Level 2		Level 3		Total
Assets:
Available-for-sale securities:
Mutual funds / exchange traded funds	Prepaid and other current assets and other non-current assets	$	19	$	—	$	—	$	19
Derivatives:
Derivative financial instruments ⁽ⁱ⁾	Prepaid and other current assets and other non-current assets	$	—	$	4	$	—	$	4
Liabilities:
Contingent consideration:
Contingent consideration ⁽ⁱⁱ⁾	Other current liabilities and other non-current liabilities	$	—	$	—	$	55	$	55
Derivatives:
Derivative financial instruments ⁽ⁱ⁾	Other current liabilities and other non-current liabilities	$	—	$	14	$	—	$	14

		Fair Value Measurements on a Recurring Basis at December 31, 2018
	Balance Sheet Location	Level 1		Level 2		Level 3		Total
Assets:
Available-for-sale securities:
Mutual funds / exchange traded funds	Prepaid and other current assets and other non-current assets	$	18	$	—	$	—	$	18
Derivatives:
Derivative financial instruments ⁽ⁱ⁾	Prepaid and other current assets and other non-current assets	$	—	$	5	$	—	$	5
Liabilities:
Contingent consideration:
Contingent consideration ⁽ⁱⁱ⁾	Other current liabilities and other non-current liabilities	$	—	$	—	$	51	$	51
Derivatives:
Derivative financial instruments ⁽ⁱ⁾	Other current liabilities and other non-current liabilities	$	—	$	17	$	—	$	17

(i)	See Note 8 — Derivative Financial Instruments for further information on our derivative investments.

(ii)

Probability weightings are based on our knowledge of the past and planned performance of the acquired entity to which the contingent consideration applies. The weighted-average discount rates used on our material contingent consideration calculations were 9.90% and 9.92% at March 31, 2019 and December 31, 2018, respectively. Using different probability weightings and discount rates could result in an increase or decrease of the contingent consideration payable.

The following table summarizes the change in fair value of the Level 3 liabilities:

Fair Value Measurements Using Significant Unobservable Inputs (Level 3)	March 31, 2019
Balance at December 31, 2018	$	51
Obligations assumed		4
Payments		(1	)
Realized and unrealized gains		—
Foreign exchange		1
Balance at March 31, 2019	$	55

There were no significant transfers between Levels 1, 2 or 3 in the three months ended March 31, 2019 and 2018, respectively.

The following tables present our liabilities not measured at fair value on a recurring basis at March 31, 2019 and December 31, 2018:

	March 31, 2019				December 31, 2018
	Carrying Value		Fair Value		Carrying Value		Fair Value
Liabilities:
Current debt	$	187	$	190	$	186	$	191
Long-term debt	$	4,518	$	4,721	$	4,389	$	4,458

The carrying value of our revolving credit facility approximates its fair value. The fair values above are not necessarily indicative of the amounts that the Company would realize upon disposition nor do they indicate the Company’s intent or ability to dispose of the financial instrument. The fair value of our respective senior notes are considered level 2 financial instruments as they are corroborated by observable market data.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Retirement Benefits

3 Months Ended

Mar. 31, 2019

Compensation And Retirement Disclosure [Abstract]

Retirement Benefits

Note 11 — Retirement Benefits

Defined Benefit Plans and Post-retirement Welfare Plans

Willis Towers Watson sponsors both qualified and non-qualified defined benefit pension plans and other post-retirement welfare (‘PRW’) plans throughout the world. The majority of our plan assets and obligations are in the U.S. and the U.K. We have also included disclosures related to defined benefit plans in certain other countries, including Canada, France, Germany and Ireland. Together, these disclosed funded and unfunded plans represent 99% of Willis Towers Watson’s pension and PRW obligations and are disclosed herein.

Components of Net Periodic Benefit (Income)/Cost for Defined Benefit Pension and Post-retirement Welfare Plans

The following table sets forth the components of net periodic benefit (income)/cost for the Company’s defined benefit pension and PRW plans for the three months ended March 31, 2019 and 2018:

	Three Months Ended March 31,
	2019												2018
	U.S.			U.K.			Other			PRW			U.S.			U.K.			Other			PRW
Service cost	$	16		$	4		$	5		$	—		$	16		$	5		$	5		$	—
Interest cost		40			24			4			1			35			24			5			1
Expected return on plan assets		(64	)		(63	)		(7	)		—			(68	)		(78	)		(8	)		—
Amortization of net loss		5			5			1			—			3			12			—			—
Amortization of prior service credit		—			(4	)		—			(1	)		—			(5	)		—			—
Net periodic benefit (income)/cost	$	(3	)	$	(34	)	$	3		$	—		$	(14	)	$	(42	)	$	2		$	1

Employer Contributions to Defined Benefit Pension Plans

The Company made no contributions to its U.S. plans for the three months ended March 31, 2019 and anticipates making $60 million in contributions over the remainder of the fiscal year. The Company made contributions of $18 million to its U.K. plans for the three months ended March 31, 2019 and anticipates making additional contributions of $58 million for the remainder of the fiscal year. The Company made contributions of $15 million to its other plans for the three months ended March 31, 2019 and anticipates making additional contributions of $7 million for the remainder of the fiscal year.

Defined Contribution Plans

The Company made contributions to its defined contribution plans of $41 million and $48 million during the three months ended March 31, 2019 and 2018, respectively.

Leases

3 Months Ended

Mar. 31, 2019

Leases [Abstract]

Leases

Note 12 — Leases

On January 1, 2019, the Company adopted ASC 842. The adoption of this new guidance had a material impact to the amounts and classifications of certain lease-related balances within our condensed consolidated financial statements and accompanying note disclosures. The Company adopted the standard using the modified retrospective approach whereby it recognized a transition adjustment at the effective date of ASC 842, January 1, 2019, rather than at the beginning of the earliest comparative period presented. The adoption of ASC 842 resulted in an additional $1.2 billion of lease liabilities and $1.0 billion of ROU assets being recognized at January 1, 2019. Furthermore, we reflected additional deferred tax assets of $252 million and deferred tax liabilities of $252 million on the gross lease liabilities and gross ROU assets, respectively. There was no adjustment to retained earnings. Rather, all operating lease-related balances, such as deferred rent accruals and lease-related intangibles, reflected on our condensed consolidated balance sheet as of December 31, 2018 were reclassified as a reduction to the opening ROU asset balance in accordance with the new guidance on January 1, 2019. Likewise, existing deferred taxes on operating lease-related balances have been reclassified as a reduction to the deferred tax liabilities related to the ROU assets.

•

We assessed the transition practical expedients available under the guidance and, in addition to selecting the modified retrospective transition approach as noted above, we made the following elections:

Practical expedient package – We elected this package, and therefore did not reassess lease classifications for our existing or expired leases, whether any existing or expired contracts contain a lease, or our treatment of any initial direct costs.

Hindsight practical expedient – As permitted under the transition rules, the Company did not revisit its estimate of lease terms upon transition to ASC 842.

Short-term lease exemption – We elected this exemption, and therefore did not recognize any right-of-use assets or liabilities for short-term leases (generally defined as having a term of 12 months or less) on our condensed consolidated balance sheet.

Separation of lease and non-lease components – We elected the practical expedient to not separate the cash flows associated with lease and non-lease components in our lease accounting and resulting amounts recorded in our condensed consolidated financial statements.

The following table presents amounts recorded on our condensed consolidated balance sheet at March 31, 2019, classified as either operating or finance leases. Operating leases are presented separately on our condensed consolidated balance sheet. For the finance leases, the ROU assets are included in fixed assets, net, and the liabilities are classified within other current liabilities or other non-current liabilities.

	Operating Leases		Finance Leases		Total Leases
Right-of-use assets	$	946	$	14	$	960
Current lease liabilities		158		3		161
Long-term lease liabilities		961		25		986

The following table presents amounts recorded on our condensed consolidated statement of comprehensive income for the three months ended March 31, 2019:

	Three Months Ended March 31, 2019
Finance lease cost:
Amortization of right-of-use assets	$	1
Interest on lease liabilities		1
Operating lease cost		48
Short-term lease cost		—
Variable lease cost		13
Sublease income		(4	)
Total lease cost, net	$	59

The total lease cost is recognized in different locations in our condensed consolidated statement of comprehensive income. Amortization of the finance lease ROU assets is included in depreciation, while the interest cost component of these finance leases is included in interest expense. All other costs are included in other operating expenses. The Company had rent expense of $64 million, net of sublease income, for the three months ended March 31, 2018 related to operating leases classified within other operating expenses on our condensed consolidated statement of comprehensive income.

Cash paid for amounts included in the measurement of lease liabilities for the three months ended March 31, 2019, as well as their location in the condensed consolidated statement of cash flows, is as follows:

	Three Months Ended March 31, 2019
Cash flows from operating activities:
Operating leases	$	55
Finance leases		1
Cash flows from financing activities:
Finance leases		1
Total lease payments	$	57

There were immaterial ROU assets acquired during the three months ended March 31, 2019.

Our operating and finance leases have the following weighted-average terms and discount rates as of March 31, 2019:

	Operating Leases			Finance Leases
Weighted-average term		9.1			6.8
Weighted-discount rate		3.6	%		12.9	%

The maturity of our lease liabilities on an undiscounted basis, including a reconciliation to the total lease liabilities reported on the condensed consolidated balance sheet as of March 31, 2019, is as follows:

	Operating Leases			Finance Leases			Total Leases
Remainder of 2019	$	147		$	4		$	151
2020		180			6			186
2021		160			6			166
2022		142			6			148
2023		132			6			138
Thereafter		552			14			566
Total future lease payments		1,313			42			1,355
Interest		(194	)		(14	)		(208	)
Total lease liabilities	$	1,119		$	28		$	1,147

Prior to the adoption of ASC 842, on December 31, 2018, the maturity of our operating and finance leases on an undiscounted basis was as follows:

	Operating Leases			Finance Leases			Total Leases
2019	$	197		$	5		$	202
2020		180			6			186
2021		159			6			165
2022		142			6			148
2023		131			6			137
Thereafter		542			14			556
Total future lease payments		1,351			43			1,394
Interest		(202	)		(14	)		(216	)
Total lease liabilities	$	1,149		$	29		$	1,178

Commitments and Contingencies

3 Months Ended

Mar. 31, 2019

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

Note 13 — Commitments and Contingencies

Indemnification Agreements

Willis Towers Watson has various agreements which provide that it may be obligated to indemnify the other party to the agreement with respect to certain matters. Generally, these indemnification provisions are included in contracts arising in the normal course of business and in connection with the purchase and sale of certain businesses. Although it is not possible to predict the maximum potential amount of future payments that may become due under these indemnification agreements because of the conditional nature of the Company’s obligations and the unique facts of each particular agreement, we do not believe that any potential liability that may arise from such indemnity provisions is probable or material. There are no provisions for recourse to third parties, nor are any assets held by any third parties that any guarantor can liquidate to recover amounts paid under such indemnities.

Legal Proceedings

In the ordinary course of business, the Company is subject to various actual and potential claims, lawsuits and other proceedings. Some of the claims, lawsuits and other proceedings seek damages in amounts which could, if assessed, be significant. We do not expect the impact of claims or demands not described below to be material to the Company’s condensed consolidated financial statements. The Company also receives subpoenas in the ordinary course of business and, from time to time, receives requests for information in connection with governmental investigations.

Errors and omissions claims, lawsuits, and other proceedings arising in the ordinary course of business are covered in part by professional indemnity or other appropriate insurance. The terms of this insurance vary by policy year. Regarding self-insured risks, the Company has established provisions which are believed to be adequate in light of current information and legal advice, or, in certain cases, where a range of loss exists, the Company accrues the minimum amount in the range if no amount within the range is a

better estimate than any other amount. The Company adjusts such provisions from time to time according to developments. See Note 14 for the amounts accrued at March 31, 2019 and December 31, 2018 in the condensed consolidated balance sheets.

On the basis of current information, the Company does not expect that the actual claims, lawsuits and other proceedings to which it is subject, or potential claims, lawsuits, and other proceedings relating to matters of which it is aware, will ultimately have a material adverse effect on its financial condition, results of operations or liquidity. Nonetheless, given the large or indeterminate amounts sought in certain of these actions, and the inherent unpredictability of litigation and disputes with insurance companies, it is possible that an adverse outcome or settlement in certain matters could, from time to time, have a material adverse effect on the Company’s results of operations or cash flows in particular quarterly or annual periods. In addition, given the early stages of some litigation or regulatory proceedings described below, it may not be possible to predict their outcomes or resolutions, and it is possible that these events may have a material adverse effect on the Company.

The Company provides for contingent liabilities based on ASC 450, Contingencies, when it is determined that a liability, inclusive of defense costs, is probable and reasonably estimable. The contingent liabilities recorded are primarily developed actuarially. Litigation is subject to many factors which are difficult to predict so there can be no assurance that in the event of a material unfavorable result in one or more claims, we will not incur material costs.

Merger-Related Securities Litigation

On November 21, 2017, a purported former stockholder of Legacy Towers Watson filed a putative class action complaint on behalf of a putative class consisting of all Legacy Towers Watson stockholders as of October 2, 2015 against the Company, Legacy Towers Watson, Legacy Willis, ValueAct Capital Management (‘ValueAct’), and certain current and former directors and officers of Legacy Towers Watson and Legacy Willis (John Haley, Dominic Casserley, and Jeffrey Ubben), in the United States District Court for the Eastern District of Virginia. The complaint asserted claims against certain defendants under Section 14(a) of the Securities Exchange Act of 1934 (the ‘Exchange Act’) for allegedly false and misleading statements in the proxy statement for the Merger; and against other defendants under Section 20(a) of the Exchange Act for alleged ‘control person’ liability with respect to such allegedly false and misleading statements. The complaint further contended that the allegedly false and misleading statements caused stockholders of Legacy Towers Watson to accept inadequate Merger consideration. The complaint sought damages in an unspecified amount. On February 20, 2018, the court appointed the Regents of the University of California (‘Regents’) as Lead Plaintiff and Bernstein Litowitz Berger & Grossman LLP (‘Bernstein’) as Lead Counsel for the putative class, consolidated all subsequently filed, removed, or transferred actions, and captioned the consolidated action ‘In re Willis Towers Watson plc Proxy Litigation,’ Master File No. 1:17-cv-1338-AJT-JFA. On March 9, 2018, Lead Plaintiff filed an Amended Complaint. On April 13, 2018, the defendants filed motions to dismiss the Amended Complaint, and, on July 11, 2018, following briefing and argument, the court granted the motions and dismissed the Amended Complaint in its entirety. On July 30, 2018, Lead Plaintiff filed a notice of appeal from the court’s July 11, 2018 dismissal order to the United States Court of Appeals for the Fourth Circuit, and, on December 6, 2018, the parties completed briefing on the appeal. The appeal is scheduled to be argued on May 8, 2019.

On February 27, 2018 and March 8, 2018, two additional purported former stockholders of Legacy Towers Watson, City of Fort Myers General Employees’ Pension Fund (‘Fort Myers’) and Alaska Laborers-Employers Retirement Trust (‘Alaska’), filed putative class action complaints on behalf of a putative class of Legacy Towers Watson stockholders against the former members of the Legacy Towers Watson board of directors, Legacy Towers Watson, Legacy Willis and ValueAct, in the Delaware Court of Chancery, captioned City of Fort Myers General Employees’ Pension Fund v. Towers Watson & Co., et al., C.A. No. 2018-0132, and Alaska Laborers-Employers Retirement Trust v. Victor F. Ganzi, et al., C.A. No. 2018-0155, respectively. Based on similar allegations as the Eastern District of Virginia action described above, the complaints assert claims against the former directors of Legacy Towers Watson for breach of fiduciary duty and against Legacy Willis and ValueAct for aiding and abetting breach of fiduciary duty.

On March 9, 2018, Regents filed a putative class action complaint on behalf of a putative class of Legacy Towers Watson stockholders against the Company, Legacy Willis, ValueAct, and Messrs. Haley, Casserley, and Ubben, in the Delaware Court of Chancery, captioned The Regents of the University of California v. John J. Haley, et al., C.A. No. 2018-0166. Based on similar allegations as the Eastern District of Virginia action described above, the complaint asserts claims against Mr. Haley for breach of fiduciary duty and against all other defendants for aiding and abetting breach of fiduciary duty. Also on March 9, 2018, Regents filed a motion for consolidation of all pending and subsequently filed Delaware Court of Chancery actions, and for appointment as Lead Plaintiff and for the appointment of Bernstein as Lead Counsel for the putative class. On March 29, 2018, Fort Myers and Alaska responded to Regents’ motion and cross-moved for appointment as Co-Lead Plaintiffs and for the appointment of their counsel, Grant & Eisenhofer P.A. and Kessler Topaz Meltzer & Check, LLP as Co-Lead Counsel. On April 2, 2018, the court consolidated the Delaware Court of Chancery actions and all related actions subsequently filed in or transferred to the Delaware Court of Chancery. On June 5, 2018, the court denied Regents’ motion for appointment of Lead Plaintiff and Lead Counsel and granted Fort Myers’ and Alaska’s cross-motion. On June 20, 2018, Fort Myers and Alaska designated the complaint previously filed by Alaska (the ‘Alaska Complaint’) as the operative complaint in the consolidated action. On September 14, 2018, the defendants filed motions to dismiss the Alaska Complaint. On October 31, 2018, Fort Myers and Alaska filed an amended complaint, which, based on similar allegations, asserts claims against the former directors of legacy Towers Watson for breach of fiduciary duty and against ValueAct and Mr. Ubben for aiding and abetting breach of fiduciary duty. On January 11, 2019, the defendants filed motions to dismiss the amended complaint,

and on March 29, 2019, the parties completed briefing on the motions. The court heard argument on the motions on April 11, 2019 and reserved judgment.

On October 18, 2018, three additional purported former stockholders of Legacy Towers Watson, Naya Master Fund LP, Naya 174 Fund Limited and Naya Lincoln Park Master Fund Limited (collectively, ‘Naya’), filed a complaint against the Company, Legacy Towers Watson, Legacy Willis and John Haley, in the Supreme Court of the State of New York, County of New York, captioned Naya Master Fund LP, et al. v. John J. Haley, et al., Index No. 654968/2018. Based on similar allegations as the Eastern District of Virginia and Delaware actions described above, the complaint asserts claims for common law fraud and negligent misrepresentation. On December 18, 2018, the defendants filed a motion to dismiss the complaint, and on March 21, 2019, the parties completed briefing on the motion. On April 23, 2019, the parties filed a Stipulation and Proposed Order Voluntarily Discontinuing Action providing for the dismissal of the action with prejudice, which the court entered on April 29, 2019.

The defendants dispute the allegations in these actions and intend to defend the lawsuits vigorously. Given the stage of the proceedings, the Company is unable to provide an estimate of the reasonably possible loss or range of loss in respect of the complaints.

Stanford Financial Group

The Company has been named as a defendant in 15 similar lawsuits relating to the collapse of The Stanford Financial Group (‘Stanford’), for which Willis of Colorado, Inc. acted as broker of record on certain lines of insurance. The complaints in these actions generally allege that the defendants actively and materially aided Stanford’s alleged fraud by providing Stanford with certain letters regarding coverage that they knew would be used to help retain or attract actual or prospective Stanford client investors. The complaints further allege that these letters, which contain statements about Stanford and the insurance policies that the defendants placed for Stanford, contained untruths and omitted material facts and were drafted in this manner to help Stanford promote and sell its allegedly fraudulent certificates of deposit.

The 15 actions are as follows:

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Troice, et al. v. Willis of Colorado, Inc., et al., C.A. No. 3:9-CV-1274-N, was filed on July 2, 2009 in the U.S. District Court for the Northern District of Texas against Willis Group Holdings plc, Willis of Colorado, Inc. and a Willis associate, among others. On April 1, 2011, plaintiffs filed the operative Third Amended Class Action Complaint individually and on behalf of a putative, worldwide class of Stanford investors, adding Willis Limited as a defendant and alleging claims under Texas statutory and common law and seeking damages in excess of $1 billion, punitive damages and costs. On May 2, 2011, the defendants filed motions to dismiss the Third Amended Class Action Complaint, arguing, inter alia, that the plaintiffs’ claims are precluded by the Securities Litigation Uniform Standards Act of 1998 (‘SLUSA’).

On May 10, 2011, the court presiding over the Stanford-related actions in the Northern District of Texas entered an order providing that it would consider the applicability of SLUSA to the Stanford-related actions based on the decision in a separate Stanford action not involving a Willis entity, Roland v. Green, Civil Action No. 3:10-CV-0224-N (‘Roland’). On August 31, 2011, the court issued its decision in Roland, dismissing that action with prejudice under SLUSA.

On October 27, 2011, the court in Troice entered an order (i) dismissing with prejudice those claims asserted in the Third Amended Class Action Complaint on a class basis on the grounds set forth in the Roland decision discussed above and (ii) dismissing without prejudice those claims asserted in the Third Amended Class Action Complaint on an individual basis. Also on October 27, 2011, the court entered a final judgment in the action.

On October 28, 2011, the plaintiffs in Troice filed a notice of appeal to the U.S. Court of Appeals for the Fifth Circuit. Subsequently, Troice, Roland and a third action captioned Troice, et al. v. Proskauer Rose LLP, Civil Action No. 3:09-CV-01600-N, which also was dismissed on the grounds set forth in the Roland decision discussed above and on appeal to the U.S. Court of Appeals for the Fifth Circuit, were consolidated for purposes of briefing and oral argument. Following the completion of briefing and oral argument, on March 19, 2012, the Fifth Circuit reversed and remanded the actions. On April 2, 2012, the defendants-appellees filed petitions for rehearing en banc. On April 19, 2012, the petitions for rehearing en banc were denied. On July 18, 2012, defendants-appellees filed a petition for writ of certiorari with the United States Supreme Court regarding the Fifth Circuit’s reversal in Troice. On January 18, 2013, the Supreme Court granted our petition. Opening briefs were filed on May 3, 2013 and the Supreme Court heard oral argument on October 7, 2013. On February 26, 2014, the Supreme Court affirmed the Fifth Circuit’s decision.

On March 19, 2014, the plaintiffs in Troice filed a Motion to Defer Resolution of Motions to Dismiss, to Compel Rule 26(f) Conference and For Entry of Scheduling Order.

On March 25, 2014, the parties in Troice and the Janvey, et al. v. Willis of Colorado, Inc., et al. action discussed below stipulated to the consolidation of the two actions for pre-trial purposes under Rule 42(a) of the Federal Rules of Civil Procedure. On March 28, 2014, the Court ‘so ordered’ that stipulation and, thus, consolidated Troice and Janvey for pre-trial purposes under Rule 42(a).

On September 16, 2014, the court (a) denied the plaintiffs’ request to defer resolution of the defendants’ motions to dismiss, but granted the plaintiffs’ request to enter a scheduling order; (b) requested the submission of supplemental briefing by all parties on the defendants’ motions to dismiss, which the parties submitted on September 30, 2014; and (c) entered an order

setting a schedule for briefing and discovery regarding plaintiffs’ motion for class certification, which schedule, among other things, provided for the submission of the plaintiffs’ motion for class certification (following the completion of briefing and discovery) on April 20, 2015.

On December 15, 2014, the court granted in part and denied in part the defendants’ motions to dismiss. On January 30, 2015, the defendants except Willis Group Holdings plc answered the Third Amended Class Action Complaint.

On April 20, 2015, the plaintiffs filed their motion for class certification, the defendants filed their opposition to plaintiffs’ motion, and the plaintiffs filed their reply in further support of the motion. Pursuant to an agreed stipulation also filed with the court on April 20, 2015, the defendants on June 4, 2015 filed sur-replies in further opposition to the motion. The Court has not yet scheduled a hearing on the motion.

On June 19, 2015, Willis Group Holdings plc filed a motion to dismiss the complaint for lack of personal jurisdiction. On November 17, 2015, Willis Group Holdings plc withdrew the motion.

On March 31, 2016, the parties in the Troice and Janvey actions entered into a settlement in principle that is described in more detail below.

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Ranni v. Willis of Colorado, Inc., et al., C.A. No. 9-22085, was filed on July 17, 2009 against Willis Group Holdings plc and Willis of Colorado, Inc. in the U.S. District Court for the Southern District of Florida. The complaint was filed on behalf of a putative class of Venezuelan and other South American Stanford investors and alleges claims under Section 10(b) of the Securities Exchange Act of 1934 (and Rule 10b-5 thereunder) and Florida statutory and common law and seeks damages in an amount to be determined at trial. On October 6, 2009, Ranni was transferred, for consolidation or coordination with other Stanford-related actions (including Troice), to the Northern District of Texas by the U.S. Judicial Panel on Multidistrict Litigation (the ‘JPML’). The defendants have not yet responded to the complaint in Ranni. On August 26, 2014, the plaintiff filed a notice of voluntary dismissal of the action without prejudice.

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Canabal, et al. v. Willis of Colorado, Inc., et al., C.A. No. 3:9-CV-1474-D, was filed on August 6, 2009 against Willis Group Holdings plc, Willis of Colorado, Inc. and the same Willis associate named as a defendant in Troice, among others, also in the Northern District of Texas. The complaint was filed individually and on behalf of a putative class of Venezuelan Stanford investors, alleged claims under Texas statutory and common law and sought damages in excess of $1 billion, punitive damages, attorneys’ fees and costs. On December 18, 2009, the parties in Troice and Canabal stipulated to the consolidation of those actions (under the Troice civil action number), and, on December 31, 2009, the plaintiffs in Canabal filed a notice of dismissal, dismissing the action without prejudice.

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Rupert, et al. v. Winter, et al., Case No. 2009C115137, was filed on September 14, 2009 on behalf of 97 Stanford investors against Willis Group Holdings plc, Willis of Colorado, Inc. and the same Willis associate, among others, in Texas state court (Bexar County). The complaint alleges claims under the Securities Act of 1933, Texas and Colorado statutory law and Texas common law and seeks special, consequential and treble damages of more than $300 million, attorneys’ fees and costs. On October 20, 2009, certain defendants, including Willis of Colorado, Inc., (i) removed Rupert to the U.S. District Court for the Western District of Texas, (ii) notified the JPML of the pendency of this related action and (iii) moved to stay the action pending a determination by the JPML as to whether it should be transferred to the Northern District of Texas for consolidation or coordination with the other Stanford-related actions. On April 1, 2010, the JPML issued a final transfer order for the transfer of Rupert to the Northern District of Texas. On January 24, 2012, the court remanded Rupert to Texas state court (Bexar County), but stayed the action until further order of the court. On August 13, 2012, the plaintiffs filed a motion to lift the stay, which motion was denied by the court on September 16, 2014. On October 10, 2014, the plaintiffs appealed the court’s denial of their motion to lift the stay to the U.S. Court of Appeals for the Fifth Circuit. On January 5, 2015, the Fifth Circuit consolidated the appeal with the appeal in the Rishmague, et ano. v. Winter, et al. action discussed below, and the consolidated appeal, was fully briefed as of March 24, 2015. Oral argument on the consolidated appeal was held on September 2, 2015. On September 16, 2015, the Fifth Circuit affirmed. The defendants have not yet responded to the complaint in Rupert.

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Casanova, et al. v. Willis of Colorado, Inc., et al., C.A. No. 3:10-CV-1862-O, was filed on September 16, 2010 on behalf of seven Stanford investors against Willis Group Holdings plc, Willis Limited, Willis of Colorado, Inc. and the same Willis associate, among others, also in the Northern District of Texas. The complaint alleges claims under Texas statutory and common law and seeks actual damages in excess of $5 million, punitive damages, attorneys’ fees and costs. On February 13, 2015, the parties filed an Agreed Motion for Partial Dismissal pursuant to which they agreed to the dismissal of certain claims pursuant to the motion to dismiss decisions in the Troice action discussed above and the Janvey action discussed below. Also on February 13, 2015, the defendants except Willis Group Holdings plc answered the complaint in the Casanova action. On June 19, 2015, Willis Group Holdings plc filed a motion to dismiss the complaint for lack of personal jurisdiction. Plaintiffs have not opposed the motion.

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Rishmague, et ano. v. Winter, et al., Case No. 2011CI2585, was filed on March 11, 2011 on behalf of two Stanford investors, individually and as representatives of certain trusts, against Willis Group Holdings plc, Willis of Colorado, Inc., Willis of Texas, Inc. and the same Willis associate, among others, in Texas state court (Bexar County). The complaint alleges claims under Texas and Colorado statutory law and Texas common law and seeks special, consequential and treble damages of more

than $37 million and attorneys’ fees and costs. On April 11, 2011, certain defendants, including Willis of Colorado, Inc., (i) removed Rishmague to the Western District of Texas, (ii) notified the JPML of the pendency of this related action and (iii) moved to stay the action pending a determination by the JPML as to whether it should be transferred to the Northern District of Texas for consolidation or coordination with the other Stanford-related actions. On August 8, 2011, the JPML issued a final transfer order for the transfer of Rishmague to the Northern District of Texas, where it is currently pending. On August 13, 2012, the plaintiffs joined with the plaintiffs in the Rupert action in their motion to lift the court’s stay of the Rupert action. On September 9, 2014, the court remanded Rishmague to Texas state court (Bexar County), but stayed the action until further order of the court and denied the plaintiffs’ motion to lift the stay. On October 10, 2014, the plaintiffs appealed the court’s denial of their motion to lift the stay to the Fifth Circuit. On January 5, 2015, the Fifth Circuit consolidated the appeal with the appeal in the Rupert action, and the consolidated appeal was fully briefed as of March 24, 2015. Oral argument on the consolidated appeal was held on September 2, 2015. On September 16, 2015, the Fifth Circuit affirmed. The defendants have not yet responded to the complaint in Rishmague.

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MacArthur v. Winter, et al., Case No. 2013-07840, was filed on February 8, 2013 on behalf of two Stanford investors against Willis Group Holdings plc, Willis of Colorado, Inc., Willis of Texas, Inc. and the same Willis associate, among others, in Texas state court (Harris County). The complaint alleges claims under Texas and Colorado statutory law and Texas common law and seeks actual, special, consequential and treble damages of approximately $4 million and attorneys’ fees and costs. On March 29, 2013, Willis of Colorado, Inc. and Willis of Texas, Inc. (i) removed MacArthur to the U.S. District Court for the Southern District of Texas and (ii) notified the JPML of the pendency of this related action. On April 2, 2013, Willis of Colorado, Inc. and Willis of Texas, Inc. filed a motion in the Southern District of Texas to stay the action pending a determination by the JPML as to whether it should be transferred to the Northern District of Texas for consolidation or coordination with the other Stanford-related actions. Also on April 2, 2013, the court presiding over MacArthur in the Southern District of Texas transferred the action to the Northern District of Texas for consolidation or coordination with the other Stanford-related actions. On September 29, 2014, the parties stipulated to the remand (to Texas state court (Harris County)) and stay of MacArthur until further order of the court (in accordance with the court’s September 9, 2014 decision in Rishmague (discussed above)), which stipulation was ‘so ordered’ by the court on October 14, 2014. The defendants have not yet responded to the complaint in MacArthur.

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Florida suits: On February 14, 2013, five lawsuits were filed against Willis Group Holdings plc, Willis Limited and Willis of Colorado, Inc. in Florida state court (Miami-Dade County), alleging violations of Florida common law. The five suits are: (1) Barbar, et al. v. Willis Group Holdings Public Limited Company, et al., Case No. 13-05666CA27, filed on behalf of 35 Stanford investors seeking compensatory damages in excess of $30 million; (2) de Gadala-Maria, et al. v. Willis Group Holdings Public Limited Company, et al., Case No. 13-05669CA30, filed on behalf of 64 Stanford investors seeking compensatory damages in excess of $83.5 million; (3) Ranni, et ano. v. Willis Group Holdings Public Limited Company, et al., Case No. 13-05673CA06, filed on behalf of two Stanford investors seeking compensatory damages in excess of $3 million; (4) Tisminesky, et al. v. Willis Group Holdings Public Limited Company, et al., Case No. 13-05676CA09, filed on behalf of 11 Stanford investors seeking compensatory damages in excess of $6.5 million; and (5) Zacarias, et al. v. Willis Group Holdings Public Limited Company, et al., Case No. 13-05678CA11, filed on behalf of 10 Stanford investors seeking compensatory damages in excess of $12.5 million. On June 3, 2013, Willis of Colorado, Inc. removed all five cases to the Southern District of Florida and, on June 4, 2013, notified the JPML of the pendency of these related actions. On June 10, 2013, the court in Tisminesky issued an order sua sponte staying and administratively closing that action pending a determination by the JPML as to whether it should be transferred to the Northern District of Texas for consolidation and coordination with the other Stanford-related actions. On June 11, 2013, Willis of Colorado, Inc. moved to stay the other four actions pending the JPML’s transfer decision. On June 20, 2013, the JPML issued a conditional transfer order for the transfer of the five actions to the Northern District of Texas, the transmittal of which was stayed for seven days to allow for any opposition to be filed. On June 28, 2013, with no opposition having been filed, the JPML lifted the stay, enabling the transfer to go forward.

On September 30, 2014, the court denied the plaintiffs’ motion to remand in Zacarias, and, on October 3, 2014, the court denied the plaintiffs’ motions to remand in Tisminesky and de Gadala Maria. On December 3, 2014 and March 3, 2015, the court granted the plaintiffs’ motions to remand in Barbar and Ranni, respectively, remanded both actions to Florida state court (Miami-Dade County) and stayed both actions until further order of the court. On January 2, 2015 and April 1, 2015, the plaintiffs in Barbar and Ranni, respectively, appealed the court’s December 3, 2014 and March 3, 2015 decisions to the Fifth Circuit. On April 22, 2015 and July 22, 2015, respectively, the Fifth Circuit dismissed the Barbar and Ranni appeals sua sponte for lack of jurisdiction. The defendants have not yet responded to the complaints in Ranni or Barbar.

On April 1, 2015, the defendants except Willis Group Holdings plc filed motions to dismiss the complaints in Zacarias, Tisminesky and de Gadala-Maria. On June 19, 2015, Willis Group Holdings plc filed motions to dismiss the complaints in Zacarias, Tisminesky and de Gadala-Maria for lack of personal jurisdiction. On July 15, 2015, the court dismissed the complaint in Zacarias in its entirety with leave to replead within 21 days. On July 21, 2015, the court dismissed the complaints in Tisminesky and de Gadala-Maria in their entirety with leave to replead within 21 days. On August 6, 2015, the plaintiffs in Zacarias, Tisminesky and de Gadala-Maria filed amended complaints (in which, among other things, Willis

Group Holdings plc was no longer named as a defendant). On September 11, 2015, the defendants filed motions to dismiss the amended complaints. The motions await disposition by the court.

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Janvey, et al. v. Willis of Colorado, Inc., et al., Case No. 3:13-CV-03980-D, was filed on October 1, 2013 also in the Northern District of Texas against Willis Group Holdings plc, Willis Limited, Willis North America Inc., Willis of Colorado, Inc. and the same Willis associate. The complaint was filed (i) by Ralph S. Janvey, in his capacity as Court-Appointed Receiver for the Stanford Receivership Estate, and the Official Stanford Investors Committee (the ‘OSIC’) against all defendants and (ii) on behalf of a putative, worldwide class of Stanford investors against Willis North America Inc. Plaintiffs Janvey and the OSIC allege claims under Texas common law and the court’s Amended Order Appointing Receiver, and the putative class plaintiffs allege claims under Texas statutory and common law. Plaintiffs seek actual damages in excess of $1 billion, punitive damages and costs. As alleged by the Stanford Receiver, the total amount of collective losses allegedly sustained by all investors in Stanford certificates of deposit is approximately $4.6 billion.

On November 15, 2013, plaintiffs in Janvey filed the operative First Amended Complaint, which added certain defendants unaffiliated with Willis. On February 28, 2014, the defendants filed motions to dismiss the First Amended Complaint, which motions, other than with respect to Willis Group Holding plc’s motion to dismiss for lack of personal jurisdiction, were granted in part and denied in part by the court on December 5, 2014. On December 22, 2014, Willis filed a motion to amend the court’s December 5 order to certify an interlocutory appeal to the Fifth Circuit, and, on December 23, 2014, Willis filed a motion to amend and, to the extent necessary, reconsider the court’s December 5 order. On January 16, 2015, the defendants answered the First Amended Complaint. On January 28, 2015, the court denied Willis’s motion to amend the court’s December 5 order to certify an interlocutory appeal to the Fifth Circuit. On February 4, 2015, the court granted Willis’s motion to amend and, to the extent necessary, reconsider the December 5 order.

As discussed above, on March 25, 2014, the parties in Troice and Janvey stipulated to the consolidation of the two actions for pre-trial purposes under Rule 42(a) of the Federal Rules of Civil Procedure. On March 28, 2014, the Court ‘so ordered’ that stipulation and, thus, consolidated Troice and Janvey for pre-trial purposes under Rule 42(a).

On January 26, 2015, the court entered an order setting a schedule for briefing and discovery regarding the plaintiffs’ motion for class certification, which schedule, among other things, provided for the submission of the plaintiffs’ motion for class certification (following the completion of briefing and discovery) on July 20, 2015. By letter dated March 4, 2015, the parties requested that the court consolidate the scheduling orders entered in Troice and Janvey to provide for a class certification submission date of April 20, 2015 in both cases. On March 6, 2015, the court entered an order consolidating the scheduling orders in Troice and Janvey, providing for a class certification submission date of April 20, 2015 in both cases, and vacating the July 20, 2015 class certification submission date in the original Janvey scheduling order.

On November 17, 2015, Willis Group Holdings plc withdrew its motion to dismiss for lack of personal jurisdiction.

On March 31, 2016, the parties in the Troice and Janvey actions entered into a settlement in principle that is described in more detail below.

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Martin v. Willis of Colorado, Inc., et al., Case No. 201652115, was filed on August 5, 2016, on behalf of one Stanford investor against Willis Group Holdings plc, Willis Limited, Willis of Colorado, Inc. and the same Willis associate in Texas state court (Harris County). The complaint alleges claims under Texas statutory and common law and seeks actual damages of less than $100,000, exemplary damages, attorneys’ fees and costs. On September 12, 2016, the plaintiff filed an amended complaint, which added five more Stanford investors as plaintiffs and seeks damages in excess of $1 million. The defendants have not yet responded to the amended complaint in Martin.

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Abel, et al. v. Willis of Colorado, Inc., et al., C.A. No. 3:16-cv-2601, was filed on September 12, 2016, on behalf of more than 300 Stanford investors against Willis Group Holdings plc, Willis Limited, Willis of Colorado, Inc. and the same Willis associate, also in the Northern District of Texas. The complaint alleges claims under Texas statutory and common law and seeks actual damages in excess of $135 million, exemplary damages, attorneys’ fees and costs. On November 10, 2016, the plaintiffs filed an amended complaint, which, among other things, added several more Stanford investors as plaintiffs. The defendants have not yet responded to the complaint in Abel.

The plaintiffs in Janvey and Troice and the other actions above seek overlapping damages, representing either the entirety or a portion of the total alleged collective losses incurred by investors in Stanford certificates of deposit, notwithstanding the fact that Legacy Willis acted as broker of record for only a portion of time that Stanford issued certificates of deposit. In the fourth quarter of 2015, the Company recognized a $70 million litigation provision for loss contingencies relating to the Stanford matters based on its ongoing review of a variety of factors as required by accounting standards.

On March 31, 2016, the Company entered into a settlement in principle for $120 million relating to this litigation, and increased its provisions by $50 million during that quarter. Further details on this settlement in principle are given below.

The settlement is contingent on a number of conditions, including court approval of the settlement and a bar order prohibiting any continued or future litigation against Willis related to Stanford, which may not be given. Therefore, the ultimate resolution of these

matters may differ from the amount provided for. The Company continues to dispute the allegations and, to the extent litigation proceeds, to defend the lawsuits vigorously.

Settlement. On March 31, 2016, the Company entered into a settlement in principle, as reflected in a Settlement Term Sheet, relating to the Stanford litigation matter. The Company agreed to the Settlement Term Sheet to eliminate the distraction, burden, expense and uncertainty of further litigation. In particular, the settlement and the related bar orders described below, if upheld through any appeals, would enable the Company (a newly-combined firm) to conduct itself with the bar orders’ protection from the continued overhang of matters alleged to have occurred approximately a decade ago. Further, the Settlement Term Sheet provided that the parties understood and agreed that there is no admission of liability or wrongdoing by the Company. The Company expressly denies any liability or wrongdoing with respect to the matters alleged in the Stanford litigation.

On or about August 31, 2016, the parties to the settlement signed a formal Settlement Agreement memorializing the terms of the settlement as originally set forth in the Settlement Term Sheet. The parties to the Settlement Agreement are Ralph S. Janvey (in his capacity as the Court-appointed receiver (the ‘Receiver’) for The Stanford Financial Group and its affiliated entities in receivership (collectively, ‘Stanford’)), the Official Stanford Investors Committee, Samuel Troice, Martha Diaz, Paula Gilly-Flores, Punga Punga Financial, Ltd., Manuel Canabal, Daniel Gomez Ferreiro and Promotora Villa Marina, C.A. (collectively, ‘Plaintiffs’), on the one hand, and Willis Towers Watson Public Limited Company (formerly Willis Group Holdings Public Limited Company), Willis Limited, Willis North America Inc., Willis of Colorado, Inc. and the Willis associate referenced above (collectively, ‘Defendants’), on the other hand. Under the terms of the Settlement Agreement, the parties agreed to settle and dismiss the Janvey and Troice actions (collectively, the ‘Actions’) and all current or future claims arising from or related to Stanford in exchange for a one-time cash payment to the Receiver by the Company of $120 million to be distributed to all Stanford investors who have claims recognized by the Receiver pursuant to the distribution plan in place at the time the payment is made.

The Settlement Agreement also provides the parties’ agreement to seek the Court’s entry of bar orders prohibiting any continued or future litigation against the Defendants and their related parties of claims relating to Stanford, whether asserted to date or not. The terms of the bar orders therefore would prohibit all Stanford-related litigation described above, and not just the Actions, but including any pending matters and any actions that may be brought in the future. Final Court approval of these bar orders is a condition of the settlement.

On September 7, 2016, Plaintiffs filed with the Court a motion to approve the settlement. On October 19, 2016, the Court preliminarily approved the settlement. Several of the plaintiffs in the other actions above objected to the settlement, and a hearing to consider final approval of the settlement was held on January 20, 2017, after which the Court reserved decision. On August 23, 2017, the Court approved the settlement, including the bar orders. Several of the objectors appealed the settlement approval and bar orders to the Fifth Circuit. The briefing related to the appeals is now completed and oral argument on the appeals was heard on December 3, 2018. There is no date certain for when the appeals will be decided.

The Company will not make the $120 million settlement payment unless and until the appeals are decided in its favor and the settlement is not subject to any further appeal.

Aviation Broking Competition Investigations

In April 2017, the Financial Conduct Authority (‘FCA’) informed Willis Limited, our U.K. broking subsidiary, that it had opened a formal investigation into possible agreements/concerted practices in the aviation broking sector.

In October 2017, the European Commission (‘Commission’) disclosed to us that it has initiated civil investigation proceedings in respect of a suspected infringement of E.U. competition rules involving several broking firms, including our principal U.K. broking subsidiary and one of its parent entities. In particular, the Commission has stated that the civil proceedings concern the exchange of commercially sensitive information between competitors in relation to aviation and aerospace insurance and reinsurance broking products and services in the European Economic Area, as well as possible coordination between competitors. The initiation of proceedings does not mean there has been a finding of infringement, merely that the Commission will investigate the case. We are providing information to the Commission as requested.

When the Commission initiated these proceedings, the FCA closed its related competition investigation, but still retained jurisdiction over broking regulatory matters arising from this conduct. In early 2018, the FCA advised that it will not be taking enforcement action against Willis Limited in connection with any such broking regulatory matters.

In May 2018, the Korea Fair Trade Commission (‘KFTC’) disclosed to us that it is investigating alleged cartels in the insurance broking industry. The KFTC has since requested information related to, among other topics, the aviation and aerospace insurance brokerage market and exchanges of information between brokers about insurance policies.

In January 2019, the Brazil Conselho Administrativo de Defesa Economica (‘CADE’) launched an administrative proceeding to investigate alleged sharing of competitive and commercially sensitive information in the insurance and reinsurance brokerage industry for aviation and aerospace and related ancillary services. The CADE identified 11 entities under investigation, including Willis Group Limited, one of our U.K. subsidiaries.

Given the status of these investigations, the Company is currently unable to assess the terms on which they will be resolved, or any other regulatory matter or civil claims emanating from the conduct being investigated, will be resolved, and thus is unable to provide an estimate of the reasonably possible loss or range of loss.

U.K. Investment Consulting Investigation

In September 2017, the FCA announced that it would make a referral with respect to the investment consulting industry to the U.K. Competition & Markets Authority (the ‘CMA’). The CMA then commenced a market investigation, and the Company is currently cooperating with the investigation.

The CMA released its final report on December 12, 2018, finding that there is an adverse effect on competition. To address these findings, the CMA has proposed certain remedies, including mandatory tendering when trustees first purchase fiduciary management services, the reporting of investment performance to customers using a set of common standards, transparency in reporting of fees in fiduciary management and the expansion of the FCA’s regulatory perimeter to include the main activities of investment consultancy and fiduciary management providers. The Company is generally supportive of these proposed remedies. The CMA will implement the remedies by way of an order on pension scheme trustees and firms providing the relevant services. The remedies are expected to be effective later in 2019, and the Company does not expect compliance costs associated with these remedies to have a material impact on its condensed consolidated financial statements.

Supplementary Information for Certain Balance Sheet Accounts

3 Months Ended

Mar. 31, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Supplementary Information for Certain Balance Sheet Accounts

Note 14 — Supplementary Information for Certain Balance Sheet Accounts

Additional details of specific balance sheet accounts are detailed below.

Deferred revenue and accrued expenses consist of the following:

	March 31, 2019		December 31, 2018
Accounts payable, accrued liabilities and deferred income	$	688	$	691
Accrued discretionary and incentive compensation		327		758
Accrued vacation		143		111
Other employee-related liabilities		82		87
Total deferred revenue and accrued expenses	$	1,240	$	1,647

Provision for liabilities consists of the following:

	March 31, 2019		December 31, 2018
Claims, lawsuits and other proceedings	$	460	$	455
Other provisions		83		85
Total provision for liabilities	$	543	$	540

Other non-current liabilities consists of the following:

	March 31, 2019		December 31, 2018
Incentives from lessors	$	—	$	120
Deferred compensation plan liability		132		125
Contingent and deferred consideration on acquisitions		25		22
Liabilities for uncertain tax positions		48		46
Finance leases		25		26
Other non-current liabilities		66		90
Total other non-current liabilities	$	296	$	429

Accumulated Other Comprehensive Loss

3 Months Ended

Mar. 31, 2019

Equity [Abstract]

Accumulated Other Comprehensive Loss

Note 15 — Accumulated Other Comprehensive Loss

Changes in accumulated other comprehensive loss, net of non-controlling interests, and net of tax are provided in the following tables for the three months ended March 31, 2019 and 2018. These tables exclude amounts attributable to non-controlling interests, which are not material for further disclosure.

	Foreign currency translation ⁽ⁱ⁾						Cash flow hedges⁽ⁱ⁾						Defined pension and post-retirement benefit costs ⁽ⁱⁱ⁾						Total
	2019			2018			2019			2018			2019			2018			2019			2018
Balance at December 31, 2018 and 2017, respectively	$	(616	)	$	(365	)	$	(8	)	$	(10	)	$	(1,337	)	$	(1,138	)	$	(1,961	)	$	(1,513	)
Other comprehensive income/(loss) before reclassifications		9			58			6			9			1			(1	)		16			66
Loss reclassified from accumulated other comprehensive loss (net of income tax benefit of $4 and $1, respectively)		—			—			5			10			2			7			7			17
Reclassification of tax effects per ASU 2018-02 ⁽ⁱⁱⁱ⁾		—			—			—			—			(36	)		—			(36	)		—
Net current-period other comprehensive income/(loss)		9			58			11			19			(33	)		6			(13	)		83
Balance at March 31, 2019 and 2018, respectively	$	(607	)	$	(307	)	$	3		$	9		$	(1,370	)	$	(1,132	)	$	(1,974	)	$	(1,430	)

(i)

Reclassification adjustments from accumulated other comprehensive loss related to foreign currency translation and cash flow hedges are included in Revenue, Salaries and benefits, and Other income, net in the accompanying condensed consolidated statements of comprehensive income. See Note 8 — Derivative Financial Instruments for additional details regarding the reclassification adjustments for the hedge settlements.

(ii)	Reclassification adjustments from accumulated other comprehensive loss are included in the computation of net periodic pension cost (see Note 11 — Retirement Benefits). These components are included in Other income, net in the accompanying condensed consolidated statements of comprehensive income.

(iii)

On January 1, 2019, in accordance with ASU 2018-02, we reclassified to Retained earnings $36 million of defined pension and postretirement costs, representing the ‘stranded’ tax effect of the change in the U.S. federal corporate tax rate resulting from U.S. Tax Reform. See Note 2 — Basis of Presentation and Recent Accounting Pronouncements for further information.

Earnings Per Share

3 Months Ended

Mar. 31, 2019

Earnings Per Share [Abstract]

Earnings Per Share

Note 16 — Earnings Per Share

Basic and diluted earnings per share are calculated by dividing net income attributable to Willis Towers Watson by the average number of ordinary shares outstanding during each period. The computation of diluted earnings per share reflects the potential dilution that could occur if dilutive securities and other contracts to issue shares were exercised or converted into shares or resulted in the issuance of shares that then shared in the net income of the Company.

At March 31, 2019 and 2018, there were 0.3 million and 0.7 million time-based share options; 0.4 million and 0.6 million performance-based options; and 0.5 million and 0.7 million restricted performance-based stock units outstanding, respectively. The Company’s restricted time-based stock units were immaterial at March 31, 2019; there were 0.1 million restricted time-based stock units outstanding at March 31, 2018. In addition, the Company had 0.3 million performance-based phantom units outstanding at March 31, 2019; there were no phantom units outstanding at March 31, 2018.

Basic and diluted earnings per share are as follows:

	Three Months Ended March 31,
	2019			2018
Net income attributable to Willis Towers Watson	$	287		$	215

Basic average number of shares outstanding		130			133
Dilutive effect of potentially issuable shares		—			—
Diluted average number of shares outstanding		130			133

Basic earnings per share	$	2.21		$	1.62
Dilutive effect of potentially issuable shares		(0.01	)		(0.01	)
Diluted earnings per share	$	2.20		$	1.61

There were no anti-dilutive options or restricted stock units for the three months ended March 31, 2019 and 2018.

Financial Information for Issuers and Other Guarantor Subsidiaries

3 Months Ended

Mar. 31, 2019

Condensed Financial Information Of Parent Company Only Disclosure [Abstract]

Financial Information for Issuers and Other Guarantor Subsidiaries

Note 17 — Financial Information for Issuers and Other Guarantor Subsidiaries

As of March 31, 2019 Willis Towers Watson has issued the following debt securities (‘WTW Debt Securities’):

Willis Towers Watson plc (the parent company) has $500 million senior notes outstanding, which were issued on March 17, 2011;

Willis North America Inc. (‘Willis North America’) has approximately $1.8 billion senior notes outstanding, of which $187 million were issued on September 29, 2009, $650 million were issued on May 16, 2017, and $1.0 billion were issued on September 10, 2018; and

Trinity Acquisition plc has approximately $2.1 billion senior notes outstanding, of which $525 million were issued on August 15, 2013, $1.0 billion were issued on March 22, 2016 and €540 million ($609 million) were issued on May 26, 2016, and $269 million currently outstanding on a consolidated basis under the $1.25 billion revolving credit facility issued on March 7, 2017.

The notes issued by the Company are guaranteed by the following additional wholly owned subsidiaries on a joint and several basis: Willis Netherlands Holdings B.V., Willis Investment U.K. Holdings Limited, TA I Limited, Trinity Acquisition plc, Willis Group Limited, Willis North America, Willis Towers Watson Sub Holdings Unlimited Company and Willis Towers Watson U.K. Holdings Limited.

As a result of an internal tax reorganization, certain subsidiaries that were previously indirectly owned by Willis North America and Trinity Acquisition plc are no longer subsidiaries of these issuer and guarantor companies, however the subsidiaries remain indirect subsidiaries of both Willis Towers Watson plc and collectively the other guarantor companies, since the subsidiaries in question are now direct and indirect subsidiaries of TA I Limited. This reorganization did not change the Company’s guarantor structure and will only result in less equity income being recorded by both issuers going forward.

The notes issued by Willis North America are guaranteed on a joint and several basis by the Company and each of the subsidiaries that guarantees the Company notes, except for Willis North America itself.

The notes issued by Trinity Acquisition plc are guaranteed on a joint and several basis by the Company and each of the subsidiaries that guarantees the Company notes, except for Trinity Acquisition plc itself.

For the purposes of this footnote, the companies that guarantee the Company notes, the Willis North America notes and the Trinity Acquisition plc notes, other than Willis North America and Trinity Acquisition plc, are referred to as the ‘other guarantors.’

The presentation of the financial information for issuers and other guarantor subsidiaries has been changed from that included in our Form 10-Q for the quarterly period ended March 31, 2018, in that the three previously disclosed separate notes that presented the three different issuer and related guarantor scenarios have been combined into one note. This new presentation retains all of the financial information of the appropriate issuing and guarantor entities, with some immaterial reclassifications from what had been previously disclosed for each entity. We believe that this presentation will help to reduce the complexity of the information and offer a more meaningful analysis for the reader.

All intercompany receivables/payables have been presented in the condensed consolidating financial statements as non-current on a net presentation basis, rather than a gross basis, as this better reflects the nature of the intercompany positions and presents the funding or funded position that is due or owed. The equity method has been used for investments in subsidiaries in the condensed consolidating balance sheets of Willis Towers Watson plc, Willis North America, Trinity Acquisition plc and the other guarantors.

Presented below is condensed financial information for:

(i)

Willis Towers Watson plc, which is both an issuer and guarantor, on a parent company only basis;

(ii)

Willis North America, which is both an issuer and guarantor, on a company only basis;

(iii)

Trinity Acquisition plc, which is both an issuer and guarantor, on a company only basis;

(iv)

Other guarantors, which are all wholly owned direct or indirect subsidiaries of the parent, on a combined basis;

(v)

Non-guarantors, which are all wholly owned direct or indirect subsidiaries of the parent, on a combined basis;

(vi)

Eliminations, which are consolidating adjustments on a combined basis; and

(vii)

The consolidated Company.

Unaudited Condensed Consolidating Statement of Comprehensive Income

	Three months ended March 31, 2019
	Willis Towers Watson plc			Willis North America			Trinity Acquisition plc			Other guarantors			Non-guarantors			Eliminations			Consolidated
Revenue	$	—		$	22		$	—		$	—		$	2,290		$	—		$	2,312
Costs of providing services
Salaries and benefits		1			15			—			—			1,332			—			1,348
Other operating expenses		1			7			—			37			373			—			418
Depreciation		—			—			—			1			53			—			54
Amortization		—			—			—			1			126			—			127
Transaction and integration expenses		—			—			—			—			6			—			6
Total costs of providing services		2			22			—			39			1,890			—			1,953
(Loss)/income from operations		(2	)		—			—			(39	)		400			—			359
Intercompany (expense)/income		—			(12	)		23			66			(77	)		—			—
Interest expense		(7	)		(21	)		(22	)		—			(4	)		—			(54	)
Other income, net		—			—			—			—			55			—			55
(LOSS)/INCOME FROM OPERATIONS BEFORE INCOME TAXES		(9	)		(33	)		1			27			374			—			360
Benefit from/(provision for) income taxes		—			7			(1	)		(4	)		(69	)		—			(67	)
Equity account for subsidiaries		296			67			221			270			—			(854	)		—
NET INCOME		287			41			221			293			305			(854	)		293
Income attributable to non-controlling interests		—			—			—			—			(6	)		—			(6	)
NET INCOME ATTRIBUTABLE TO WILLIS TOWERS WATSON	$	287		$	41		$	221		$	293		$	299		$	(854	)	$	287

Comprehensive income before non- controlling interests	$	311		$	19		$	204		$	317		$	298		$	(834	)	$	315
Comprehensive income attributable to non- controlling interests		—			—			—			—			(5	)		—			(5	)
Comprehensive income attributable to Willis Towers Watson	$	311		$	19		$	204		$	317		$	293		$	(834	)	$	310

Unaudited Condensed Consolidating Statement of Comprehensive Income

	Three months ended March 31, 2018
	Willis Towers Watson plc			Willis North America			Trinity Acquisition plc			Other guarantors			Non-guarantors			Eliminations			Consolidated
Revenue	$	—		$	6		$	—		$	—		$	2,286		$	—		$	2,292
Costs of providing services
Salaries and benefits		1			15			—			—			1,361			—			1,377
Other operating expenses		—			5			—			42			376			—			423
Depreciation		—			—			—			1			48			—			49
Amortization		—			—			—			1			140			—			141
Transaction and integration expenses		—			5			—			1			37			—			43
Total costs of providing services		1			25			—			45			1,962			—			2,033
(Loss)/income from operations		(1	)		(19	)		—			(45	)		324			—			259
Intercompany (expense)/income		—			(5	)		30			92			(117	)		—			—
Interest expense		(7	)		(11	)		(27	)		—			(6	)		—			(51	)
Other income, net		—			—			—			1			55			—			56
(LOSS)/INCOME FROM OPERATIONS BEFORE INCOME TAXES		(8	)		(35	)		3			48			256			—			264
Benefit from/(provision for) income taxes		—			5			(1	)		(8	)		(39	)		—			(43	)
Equity account for subsidiaries		223			(7	)		142			181			—			(539	)		—
NET INCOME/(LOSS)		215			(37	)		144			221			217			(539	)		221
Income attributable to non-controlling interests		—			—			—			—			(6	)		—			(6	)
NET INCOME/(LOSS) ATTRIBUTABLE TO WILLIS TOWERS WATSON	$	215		$	(37	)	$	144		$	221		$	211		$	(539	)	$	215

Comprehensive income/(loss) before non- controlling interests	$	298		$	(22	)	$	226		$	303		$	338		$	(838	)	$	305
Comprehensive income attributable to non- controlling interests		—			—			—			—			(7	)		—			(7	)
Comprehensive income/(loss) attributable to Willis Towers Watson	$	298		$	(22	)	$	226		$	303		$	331		$	(838	)	$	298

Unaudited Condensed Consolidating Balance Sheet

	As of March 31, 2019
	Willis Towers Watson plc		Willis North America		Trinity Acquisition plc		Other guarantors		Non-guarantors		Eliminations			Consolidated
ASSETS
Cash and cash equivalents	$	—	$	—	$	—	$	—	$	992	$	—		$	992
Fiduciary assets		—		—		—		—		15,129		—			15,129
Accounts receivable, net		—		28		—		—		2,462		—			2,490
Prepaid and other current assets		—		371		1		30		338		(331	)		409
Total current assets		—		399		1		30		18,921		(331	)		19,020
Intercompany receivables, net		4,733		—		1,452		—		—		(6,185	)		—
Fixed assets, net		—		—		—		17		940		—			957
Goodwill		—		—		—		—		10,456		—			10,456
Other intangible assets, net		—		—		—		57		3,187		(57	)		3,187
Right-of-use assets		—		—		—		—		946		—			946
Pension benefits assets		—		—		—		—		833		—			833
Other non-current assets		—		142		2		48		420		(118	)		494
Total non-current assets		4,733		142		1,454		122		16,782		(6,360	)		16,873
Investments in subsidiaries		5,952		6,401		2,526		7,947		—		(22,826	)		—
TOTAL ASSETS	$	10,685	$	6,942	$	3,981	$	8,099	$	35,703	$	(29,517	)	$	35,893
LIABILITIES AND EQUITY
Fiduciary liabilities	$	—	$	—	$	—	$	—	$	15,129	$	—		$	15,129
Deferred revenue and accrued expenses		—		—		—		3		1,237		—			1,240
Current debt		—		187		—		—		—		—			187
Current lease liabilities		—		—		—		—		158		—			158
Other current liabilities		97		28		19		5		1,070		(279	)		940
Total current liabilities		97		215		19		8		17,594		(279	)		17,654
Intercompany payables, net		—		748		—		4,709		728		(6,185	)		—
Long-term debt		498		1,655		2,364		—		1		—			4,518
Liability for pension benefits		—		—		—		—		1,135		—			1,135
Deferred tax liabilities		—		—		—		—		662		(118	)		544
Provision for liabilities		—		120		—		—		423		—			543
Long-term lease liabilities		—		—		—		—		961		—			961
Other non-current liabilities		—		16		—		2		278		—			296
Total non-current liabilities		498		2,539		2,364		4,711		4,188		(6,303	)		7,997
TOTAL LIABILITIES		595		2,754		2,383		4,719		21,782		(6,582	)		25,651
REDEEMABLE NON-CONTROLLING INTEREST		—		—		—		—		28		—			28
EQUITY
Total Willis Towers Watson shareholders’ equity		10,090		4,188		1,598		3,380		13,771		(22,935	)		10,092
Non-controlling interests		—		—		—		—		122		—			122
Total equity		10,090		4,188		1,598		3,380		13,893		(22,935	)		10,214
TOTAL LIABILITIES AND EQUITY	$	10,685	$	6,942	$	3,981	$	8,099	$	35,703	$	(29,517	)	$	35,893

Unaudited Condensed Consolidating Balance Sheet

	As of December 31, 2018
	Willis Towers Watson plc		Willis North America		Trinity Acquisition plc		Other guarantors		Non-guarantors		Eliminations			Consolidated
ASSETS
Cash and cash equivalents	$	—	$	—	$	—	$	—	$	1,033	$	—		$	1,033
Fiduciary assets		—		—		—		—		12,604		—			12,604
Accounts receivable, net		—		24		—		—		2,355		—			2,379
Prepaid and other current assets		—		311		1		33		357		(298	)		404
Total current assets		—		335		1		33		16,349		(298	)		16,420
Intercompany receivables, net		4,755		—		1,355		—		—		(6,110	)		—
Fixed assets, net		—		—		—		16		926		—			942
Goodwill		—		—		—		—		10,465		—			10,465
Other intangible assets, net		—		—		—		58		3,318		(58	)		3,318
Pension benefits assets		—		—		—		—		773		—			773
Other non-current assets		—		92		2		49		452		(128	)		467
Total non-current assets		4,755		92		1,357		123		15,934		(6,296	)		15,965
Investments in subsidiaries		5,691		6,649		2,677		8,108		—		(23,125	)		—
TOTAL ASSETS	$	10,446	$	7,076	$	4,035	$	8,264	$	32,283	$	(29,719	)	$	32,385
LIABILITIES AND EQUITY
Fiduciary liabilities	$	—	$	—	$	—	$	—	$	12,604	$	—		$	12,604
Deferred revenue and accrued expenses		1		2		—		3		1,641		—			1,647
Current debt		—		186		—		—		—		—			186
Other current liabilities		95		38		33		13		935		(250	)		864
Total current liabilities		96		226		33		16		15,180		(250	)		15,301
Intercompany payables, net		—		902		—		4,691		517		(6,110	)		—
Long-term debt		498		1,635		2,256		—		—		—			4,389
Liability for pension benefits		—		—		—		—		1,170		—			1,170
Deferred tax liabilities		—		—		—		—		688		(129	)		559
Provision for liabilities		—		120		—		—		420		—			540
Other non-current liabilities		—		13		—		5		411		—			429
Total non-current liabilities		498		2,670		2,256		4,696		3,206		(6,239	)		7,087
TOTAL LIABILITIES		594		2,896		2,289		4,712		18,386		(6,489	)		22,388
REDEEMABLE NON-CONTROLLING INTEREST		—		—		—		—		26		—			26
EQUITY
Total Willis Towers Watson shareholders’ equity		9,852		4,180		1,746		3,552		13,752		(23,230	)		9,852
Non-controlling interests		—		—		—		—		119		—			119
Total equity		9,852		4,180		1,746		3,552		13,871		(23,230	)		9,971
TOTAL LIABILITIES AND EQUITY	$	10,446	$	7,076	$	4,035	$	8,264	$	32,283	$	(29,719	)	$	32,385

Unaudited Condensed Consolidating Statement of Cash Flows

	Three months ended March 31, 2019
	Willis Towers Watson plc			Willis North America			Trinity Acquisition plc			Other guarantors			Non-guarantors			Eliminations			Consolidated
NET CASH FROM/(USED IN) OPERATING ACTIVITIES	$	38		$	(130	)	$	(31	)	$	(82	)	$	158		$	—		$	(47	)
CASH FLOWS FROM/(USED IN) INVESTING ACTIVITIES
Additions to fixed assets and software for internal use		—			—			—			(1	)		(56	)		—			(57	)
Capitalized software costs		—			—			—			—			(17	)		—			(17	)
Acquisitions of operations, net of cash acquired		—			—			—			—			(1	)		—			(1	)
Proceeds from/(repayments of) intercompany investing activities, net		17			111			(137	)		78			(34	)		(35	)		—
Net cash from/(used in) investing activities	$	17		$	111		$	(137	)	$	77		$	(108	)	$	(35	)	$	(75	)
CASH FLOWS (USED IN)/FROM FINANCING ACTIVITIES
Net payments on revolving credit facility		—			20			118			—			—			—			138
Repayments of debt		—			—			—			—			(1	)		—			(1	)
Proceeds from issuance of shares		22			—			—			—			—			—			22
Dividends paid		(77	)		—			—			—			—			—			(77	)
(Repayments of)/proceeds from intercompany financing activities, net		—			(1	)		50			5			(89	)		35			—
Net cash (used in)/from financing activities	$	(55	)	$	19		$	168		$	5		$	(90	)	$	35		$	82
DECREASE IN CASH AND CASH EQUIVALENTS		—			—			—			—			(40	)		—			(40	)
Effect of exchange rate changes on cash and cash equivalents		—			—			—			—			(1	)		—			(1	)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD		—			—			—			—			1,033			—			1,033
CASH AND CASH EQUIVALENTS, END OF PERIOD	$	—		$	—		$	—		$	—		$	992		$	—		$	992

Unaudited Condensed Consolidating Statement of Cash Flows

	Three months ended March 31, 2018
	Willis Towers Watson plc			Willis North America			Trinity Acquisition plc			Other guarantors			Non-guarantors			Eliminations			Consolidated
NET CASH FROM/(USED IN) OPERATING ACTIVITIES	$	72		$	(98	)	$	(196	)	$	245		$	328		$	(333	)	$	18
CASH FLOWS (USED IN)/FROM INVESTING ACTIVITIES
Additions to fixed assets and software for internal use		—			—			—			(1	)		(64	)		—			(65	)
Capitalized software costs		—			—			—			—			(13	)		—			(13	)
Acquisitions of operations, net of cash acquired		—			—			—			—			(5	)		—			(5	)
Net proceeds from sale of operations		—			—			—			—			4			—			4
(Repayments of)/proceeds from intercompany investing activities, net		(17	)		67			326			63			(195	)		(244	)		—
Net cash (used in)/from investing activities	$	(17	)	$	67		$	326		$	62		$	(273	)	$	(244	)	$	(79	)
CASH FLOWS (USED IN)/FROM FINANCING ACTIVITIES
Net borrowings on revolving credit facility		—			55			6			—			—			—			61
Repayments of debt		—			—			—			—			(21	)		—			(21	)
Proceeds from issuance of shares		11			—			—			—			—			—			11
Cash paid for employee taxes on withholding shares		—			—			—			—			(7	)		—			(7	)
Dividends paid		(68	)		—			(332	)		(1	)		—			333			(68	)
(Repayments of)/proceeds from intercompany financing activities, net		—			(24	)		196			(306	)		(110	)		244			—
Net cash (used in)/from financing activities	$	(57	)	$	31		$	(130	)	$	(307	)	$	(138	)	$	577		$	(24	)
DECREASE IN CASH AND CASH EQUIVALENTS		(2	)		—			—			—			(83	)		—			(85	)
Effect of exchange rate changes on cash and cash equivalents		—			—			—			—			9			—			9
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD		2			—			—			1			1,027			—			1,030
CASH AND CASH EQUIVALENTS, END OF PERIOD	$	—		$	—		$	—		$	1		$	953		$	—		$	954

Basis of Presentation and Recent Accounting Pronouncements (Policies)

3 Months Ended

Mar. 31, 2019

Accounting Policies [Abstract]

Basis of Presentation

Recent Accounting Pronouncements

Not Yet Adopted

financial statements upon adopting this ASU since the most recent Step 1 goodwill impairment test resulted in fair values in excess of carrying values for all reporting units at October 1, 2018.

•

Adopted

Leases

Our leases generally do not subject us to restrictive covenants and contain no residual value guarantees.

Basis of Presentation, Significant Accounting Policies and Recent Accounting Pronouncements (Policies)

3 Months Ended

Mar. 31, 2019

Accounting Policies [Abstract]

Fair Value of Financial Instruments

•

Level 1: refers to fair values determined based on quoted market prices in active markets for identical assets;

•

Level 2: refers to fair values estimated using observable market-based inputs or unobservable inputs that are corroborated by market data; and

•

Level 3: includes fair values estimated using unobservable inputs that are not corroborated by market data.

The following methods and assumptions were used by the Company in estimating its fair value disclosure for financial instruments:

•

Available-for-sale securities are classified as Level 1 because we use quoted market prices in determining the fair value of these securities.

•

Revenue (Tables)

3 Months Ended

Mar. 31, 2019

Revenue From Contract With Customer [Abstract]

Disaggregation of Revenue

The following table presents revenue by service offering and segment, as well as a reconciliation to total revenue for the three months ended March 31, 2019 and 2018. Along with reimbursable expenses and other, total revenue by service offering represents our revenue from customer contracts.

	Three Months Ended March 31,
	HCB				CRB				IRR				BDA				Corporate ⁽ⁱⁱ⁾				Total
	2019		2018		2019		2018		2019		2018		2019		2018		2019		2018		2019		2018
Broking	$	73	$	76	$	660	$	664	$	405	$	391	$	3	$	4	$	—	$	—	$	1,141	$	1,135
Consulting ⁽ⁱ⁾		580		577		31		44		114		117		—		—		3		3		728		741
Outsourced administration ⁽ⁱ⁾		123		132		27		23		2		—		132		118		—		—		284		273
Other ⁽ⁱ⁾		47		43		1		3		58		59		—		—		1		1		107		106
Total revenues by service offering		823		828		719		734		579		567		135		122		4		4		2,260		2,255
Reimbursable expenses and other ⁽ⁱⁱ⁾		14		14		—		—		2		2		3		2		7		1		26		19
Total revenue from customer contracts	$	837	$	842	$	719	$	734	$	581	$	569	$	138	$	124	$	11	$	5	$	2,286	$	2,274
Interest and other income ⁽ⁱⁱⁱ⁾		6		4		9		6		10		7		—		—		1		1		26		18
Total revenue	$	843	$	846	$	728	$	740	$	591	$	576	$	138	$	124	$	12	$	6	$	2,312	$	2,292

______________

(i)	Amounts presented for HCB Outsourced administration revenue include a correction of approximately $58 million of revenue that was previously classified as HCB Consulting revenue or HCB Other revenue in our quarterly report on Form 10-Q for the three months ended March 31, 2018.

(ii)	Reimbursable expenses and other, as well as Corporate revenue, are excluded from segment revenue, but included in total revenue on the condensed consolidated statements of comprehensive income.

(iii)

	Three Months Ended March 31,
	HCB				CRB				IRR				BDA				Corporate				Total
	2019		2018		2019		2018		2019		2018		2019		2018		2019		2018		2019		2018
North America	$	471	$	462	$	220	$	215	$	164	$	153	$	135	$	122	$	4	$	4	$	994	$	956
Great Britain		118		129		142		148		300		295		—		—		—		—		560		572
Western Europe		155		154		239		239		69		71		—		—		—		—		463		464
International		79		83		118		132		46		48		—		—		—		—		243		263
Total revenue by geography	$	823	$	828	$	719	$	734	$	579	$	567	$	135	$	122	$	4	$	4	$	2,260	$	2,255

Contract with Customer, Asset and Liability

	March 31, 2019		December 31, 2018
Billed receivables, net of allowance for doubtful accounts of $44 million and $40 million	$	1,847	$	1,702
Unbilled receivables		396		356
Current contract assets		247		321
Accounts receivable, net	$	2,490	$	2,379
Non-current accounts receivable, net	$	17	$	20
Non-current contract assets	$	6	$	3
Deferred revenue	$	483	$	448

Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction

•

Performance obligations which are part of a contract that has an original expected duration of less than one year, and

•

Performance obligations satisfied in accordance with ASC 606-10-55-18 (‘right to invoice’).

		Remainder of 2019				2020				2021 onward				Total
Revenue expected to be recognized on contracts as of March 31, 2019		$	314			$	341			$	432			$	1,087

Segment Information (Tables)

3 Months Ended

Mar. 31, 2019

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment

The following table presents segment revenue and segment operating income for our reportable segments for the three months ended March 31, 2019 and 2018.

	Three Months Ended March 31,
	HCB				CRB				IRR				BDA						Total
	2019		2018		2019		2018		2019		2018		2019			2018			2019		2018
Segment revenue	$	829	$	832	$	728	$	740	$	589	$	574	$	135		$	122		$	2,281	$	2,268

Segment operating income/(loss)	$	204	$	193	$	127	$	125	$	252	$	261	$	(21	)	$	(32	)	$	562	$	547

Net Operating Income of the Reported Segments

	Three Months Ended March 31,
	2019			2018
Revenue:
Total segment revenue	$	2,281		$	2,268
Reimbursable expenses and other		31			24
Revenue	$	2,312		$	2,292

Total segment operating income	$	562		$	547
Amortization		(127	)		(141	)
Transaction and integration expenses		(6	)		(43	)
Unallocated, net ⁽ⁱ⁾		(70	)		(104	)
Income from operations		359			259
Interest expense		(54	)		(51	)
Other income, net		55			56
Income from operations before income taxes	$	360		$	264

(i)	Includes certain costs, primarily related to corporate functions which are not directly related to the segments, and certain differences between budgeted expenses determined at the beginning of the year and actual expenses that we report for U.S. GAAP purposes.

Goodwill and Other Intangible Assets (Tables)

3 Months Ended

Mar. 31, 2019

Goodwill And Intangible Assets Disclosure [Abstract]

Components of Goodwill

The components of goodwill are outlined below for the three months ended March 31, 2019:

	HCB			CRB			IRR		BDA		Total
Balance at December 31, 2018:
Goodwill, gross	$	4,300		$	2,308		$	1,792	$	2,557	$	10,957
Accumulated impairment losses		(130	)		(362	)		—		—		(492	)
Goodwill, net - December 31, 2018		4,170			1,946			1,792		2,557		10,465
Foreign exchange		(6	)		(7	)		4		—		(9	)
Balance at March 31, 2019:
Goodwill, gross		4,294			2,301			1,796		2,557		10,948
Accumulated impairment losses		(130	)		(362	)		—		—		(492	)
Goodwill, net - March 31, 2019	$	4,164		$	1,939		$	1,796	$	2,557	$	10,456

Changes in the Net Carrying Amount of the Components of Finite-Lived Intangible Assets

The following table reflects changes in the net carrying amounts of the components of finite-lived intangible assets for the three months ended March 31, 2019:

	Balance at December 31, 2018		Intangible assets acquired		Intangible assets disposed			ASC 842 reclassification ⁽ⁱ⁾			Amortization			Foreign exchange			Balance at March 31, 2019
Client relationships	$	1,986	$	3	$	(1	)	$	—		$	(82	)	$	3		$	1,909
Management contracts		48		—		—			—			(1	)		(2	)		45
Software		328		—		—			—			(32	)		2			298
Trademark and trade name		920		—		—			—			(11	)		—			909
Product		27		—		—			—			(1	)		—			26
Favorable agreements		9		—		—			(9	)		—			—			—
Total amortizable intangible assets	$	3,318	$	3	$	(1	)	$	(9	)	$	(127	)	$	3		$	3,187

__________________

(i) On January 1, 2019, in accordance with ASC 842, we reclassified our favorable lease agreement assets to right-of-use assets within our condensed consolidated balance sheet.

Schedule of Carrying Values of Finite-Lived Intangible Assets and Liabilities

The following table reflects the carrying value of finite-lived intangible assets and liabilities at March 31, 2019 and December 31, 2018:

	March 31, 2019					December 31, 2018
	Gross carrying amount		Accumulated amortization			Gross carrying amount		Accumulated amortization
Client relationships	$	3,405	$	(1,496	)	$	3,401	$	(1,415	)
Management contracts		60		(15	)		63		(15	)
Software		754		(456	)		749		(421	)
Trademark and trade name		1,052		(143	)		1,052		(132	)
Product		36		(10	)		36		(9	)
Favorable agreements ⁽ⁱ⁾		—		—			14		(5	)
Other		2		(2	)		3		(3	)
Total finite-lived assets	$	5,309	$	(2,122	)	$	5,318	$	(2,000	)

Unfavorable agreements ⁽ⁱ⁾	$	—	$	—		$	34	$	(13	)
Total finite-lived intangible liabilities	$	—	$	—		$	34	$	(13	)

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense

The table below reflects the future estimated amortization expense for amortizable intangible assets for the remainder of 2019 and for subsequent years:

	Amortization
Remainder of 2019	$	353
2020		424
2021		347
2022		288
2023		239
Thereafter		1,536
Total	$	3,187

Derivative Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2019

Derivative Instruments And Hedging Activities Disclosure [Abstract]

Schedule of Derivative Instruments Designated As Hedging Instrument Effect on Other Comprehensive Income (Loss)

Three Months Ended March 31,	Gain recognized in OCI (effective element)
	2019		2018
Forward exchange contracts	$	8	$	15

Location of gain/(loss) reclassified from Accumulated OCL into income (effective element)	Gain/(loss) reclassified from Accumulated OCL into income (effective element)
	2019			2018
Revenue	$	1		$	—
Salaries and benefits		(5	)		—
Other income, net		—			(11	)
	$	(4	)	$	(11	)

Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss)

		Loss recognized in income
		Three Months Ended March 31,
Derivatives not designated as hedging instruments:	Location of loss recognized in income	2019			2018
Forward exchange contracts	Other income, net	$	(10	)	$	(5	)

Debt (Tables)

3 Months Ended

Mar. 31, 2019

Debt Disclosure [Abstract]

Schedule of Debt

Current debt consists of the following:

March 31,

2019

December 31,

2018

7.000% senior notes due 2019

187

186

Long-term debt consists of the following:

	March 31, 2019		December 31, 2018
Revolving $1.25 billion credit facility	$	269	$	130
5.750% senior notes due 2021		498		498
3.500% senior notes due 2021		448		448
2.125% senior notes due 2022⁽ⁱ⁾		604		615
4.625% senior notes due 2023		248		248
3.600% senior notes due 2024		646		645
4.400% senior notes due 2026		544		544
4.500% senior notes due 2028		595		595
6.125% senior notes due 2043		271		271
5.050% senior notes due 2048		395		395
	$	4,518	$	4,389

(i)	Notes issued in Euro (€540 million)

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2019

Fair Value Disclosures [Abstract]

Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis

The following tables present our assets and liabilities measured at fair value on a recurring basis at March 31, 2019 and December 31, 2018:

		Fair Value Measurements on a Recurring Basis at March 31, 2019
	Balance Sheet Location	Level 1		Level 2		Level 3		Total
Assets:
Available-for-sale securities:
Mutual funds / exchange traded funds	Prepaid and other current assets and other non-current assets	$	19	$	—	$	—	$	19
Derivatives:
Derivative financial instruments ⁽ⁱ⁾	Prepaid and other current assets and other non-current assets	$	—	$	4	$	—	$	4
Liabilities:
Contingent consideration:
Contingent consideration ⁽ⁱⁱ⁾	Other current liabilities and other non-current liabilities	$	—	$	—	$	55	$	55
Derivatives:
Derivative financial instruments ⁽ⁱ⁾	Other current liabilities and other non-current liabilities	$	—	$	14	$	—	$	14

		Fair Value Measurements on a Recurring Basis at December 31, 2018
	Balance Sheet Location	Level 1		Level 2		Level 3		Total
Assets:
Available-for-sale securities:
Mutual funds / exchange traded funds	Prepaid and other current assets and other non-current assets	$	18	$	—	$	—	$	18
Derivatives:
Derivative financial instruments ⁽ⁱ⁾	Prepaid and other current assets and other non-current assets	$	—	$	5	$	—	$	5
Liabilities:
Contingent consideration:
Contingent consideration ⁽ⁱⁱ⁾	Other current liabilities and other non-current liabilities	$	—	$	—	$	51	$	51
Derivatives:
Derivative financial instruments ⁽ⁱ⁾	Other current liabilities and other non-current liabilities	$	—	$	17	$	—	$	17

(i)	See Note 8 — Derivative Financial Instruments for further information on our derivative investments.

(ii)

Schedule of Change in Fair Value of Level 3 Liabilities

The following table summarizes the change in fair value of the Level 3 liabilities:

Fair Value Measurements Using Significant Unobservable Inputs (Level 3)	March 31, 2019
Balance at December 31, 2018	$	51
Obligations assumed		4
Payments		(1	)
Realized and unrealized gains		—
Foreign exchange		1
Balance at March 31, 2019	$	55

Schedule of Liabilities Whose Carrying Values Differ From the Fair Value and are Not Measured on a Recurring Basis

The following tables present our liabilities not measured at fair value on a recurring basis at March 31, 2019 and December 31, 2018:

	March 31, 2019				December 31, 2018
	Carrying Value		Fair Value		Carrying Value		Fair Value
Liabilities:
Current debt	$	187	$	190	$	186	$	191
Long-term debt	$	4,518	$	4,721	$	4,389	$	4,458

Retirement Benefits (Tables)

3 Months Ended

Mar. 31, 2019

Compensation And Retirement Disclosure [Abstract]

Schedule of Net Periodic Benefit Cost

The following table sets forth the components of net periodic benefit (income)/cost for the Company’s defined benefit pension and PRW plans for the three months ended March 31, 2019 and 2018:

	Three Months Ended March 31,
	2019												2018
	U.S.			U.K.			Other			PRW			U.S.			U.K.			Other			PRW
Service cost	$	16		$	4		$	5		$	—		$	16		$	5		$	5		$	—
Interest cost		40			24			4			1			35			24			5			1
Expected return on plan assets		(64	)		(63	)		(7	)		—			(68	)		(78	)		(8	)		—
Amortization of net loss		5			5			1			—			3			12			—			—
Amortization of prior service credit		—			(4	)		—			(1	)		—			(5	)		—			—
Net periodic benefit (income)/cost	$	(3	)	$	(34	)	$	3		$	—		$	(14	)	$	(42	)	$	2		$	1

Leases (Tables)

3 Months Ended

Mar. 31, 2019

Leases [Abstract]

Schedule of Lease

	Operating Leases		Finance Leases		Total Leases
Right-of-use assets	$	946	$	14	$	960
Current lease liabilities		158		3		161
Long-term lease liabilities		961		25		986

Schedule of Amount Recorded in Condensed Consolidated Statement of Comprehensive Income

The following table presents amounts recorded on our condensed consolidated statement of comprehensive income for the three months ended March 31, 2019:

	Three Months Ended March 31, 2019
Finance lease cost:
Amortization of right-of-use assets	$	1
Interest on lease liabilities		1
Operating lease cost		48
Short-term lease cost		—
Variable lease cost		13
Sublease income		(4	)
Total lease cost, net	$	59

Schedule of Cash Paid in the Measurement of Lease Liabilities

	Three Months Ended March 31, 2019
Cash flows from operating activities:
Operating leases	$	55
Finance leases		1
Cash flows from financing activities:
Finance leases		1
Total lease payments	$	57

Schedule of Weighted Average Term and Discount Rates

Our operating and finance leases have the following weighted-average terms and discount rates as of March 31, 2019:

	Operating Leases			Finance Leases
Weighted-average term		9.1			6.8
Weighted-discount rate		3.6	%		12.9	%

Schedule of Maturity of Operating and Finance Leases Liabilities

	Operating Leases			Finance Leases			Total Leases
Remainder of 2019	$	147		$	4		$	151
2020		180			6			186
2021		160			6			166
2022		142			6			148
2023		132			6			138
Thereafter		552			14			566
Total future lease payments		1,313			42			1,355
Interest		(194	)		(14	)		(208	)
Total lease liabilities	$	1,119		$	28		$	1,147

Prior to the adoption of ASC 842, on December 31, 2018, the maturity of our operating and finance leases on an undiscounted basis was as follows:

	Operating Leases			Finance Leases			Total Leases
2019	$	197		$	5		$	202
2020		180			6			186
2021		159			6			165
2022		142			6			148
2023		131			6			137
Thereafter		542			14			556
Total future lease payments		1,351			43			1,394
Interest		(202	)		(14	)		(216	)
Total lease liabilities	$	1,149		$	29		$	1,178

Supplementary Information for Certain Balance Sheet Accounts (Tables)

3 Months Ended

Mar. 31, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Schedule of Accounts Payable and Accrued Liabilities

Deferred revenue and accrued expenses consist of the following:

	March 31, 2019		December 31, 2018
Accounts payable, accrued liabilities and deferred income	$	688	$	691
Accrued discretionary and incentive compensation		327		758
Accrued vacation		143		111
Other employee-related liabilities		82		87
Total deferred revenue and accrued expenses	$	1,240	$	1,647

Provisions for Liabilities

Provision for liabilities consists of the following:

	March 31, 2019		December 31, 2018
Claims, lawsuits and other proceedings	$	460	$	455
Other provisions		83		85
Total provision for liabilities	$	543	$	540

Schedule of Other Non-current Liabilities

Other non-current liabilities consists of the following:

	March 31, 2019		December 31, 2018
Incentives from lessors	$	—	$	120
Deferred compensation plan liability		132		125
Contingent and deferred consideration on acquisitions		25		22
Liabilities for uncertain tax positions		48		46
Finance leases		25		26
Other non-current liabilities		66		90
Total other non-current liabilities	$	296	$	429

Accumulated Other Comprehensive Loss (Tables)

3 Months Ended

Mar. 31, 2019

Equity [Abstract]

Schedule of Accumulated Other Comprehensive Income (Loss)

	Foreign currency translation ⁽ⁱ⁾						Cash flow hedges⁽ⁱ⁾						Defined pension and post-retirement benefit costs ⁽ⁱⁱ⁾						Total
	2019			2018			2019			2018			2019			2018			2019			2018
Balance at December 31, 2018 and 2017, respectively	$	(616	)	$	(365	)	$	(8	)	$	(10	)	$	(1,337	)	$	(1,138	)	$	(1,961	)	$	(1,513	)
Other comprehensive income/(loss) before reclassifications		9			58			6			9			1			(1	)		16			66
Loss reclassified from accumulated other comprehensive loss (net of income tax benefit of $4 and $1, respectively)		—			—			5			10			2			7			7			17
Reclassification of tax effects per ASU 2018-02 ⁽ⁱⁱⁱ⁾		—			—			—			—			(36	)		—			(36	)		—
Net current-period other comprehensive income/(loss)		9			58			11			19			(33	)		6			(13	)		83
Balance at March 31, 2019 and 2018, respectively	$	(607	)	$	(307	)	$	3		$	9		$	(1,370	)	$	(1,132	)	$	(1,974	)	$	(1,430	)

(i)

(ii)	Reclassification adjustments from accumulated other comprehensive loss are included in the computation of net periodic pension cost (see Note 11 — Retirement Benefits). These components are included in Other income, net in the accompanying condensed consolidated statements of comprehensive income.

(iii)

Earnings Per Share (Tables)

3 Months Ended

Mar. 31, 2019

Earnings Per Share [Abstract]

Schedule of Basic and Diluted Earnings Per Share

Basic and diluted earnings per share are as follows:

	Three Months Ended March 31,
	2019			2018
Net income attributable to Willis Towers Watson	$	287		$	215

Basic average number of shares outstanding		130			133
Dilutive effect of potentially issuable shares		—			—
Diluted average number of shares outstanding		130			133

Basic earnings per share	$	2.21		$	1.62
Dilutive effect of potentially issuable shares		(0.01	)		(0.01	)
Diluted earnings per share	$	2.20		$	1.61

Financial Information for Issuers and Other Guarantor Subsidiaries (Tables)

3 Months Ended

Mar. 31, 2019

Condensed Financial Information Of Parent Company Only Disclosure [Abstract]

Unaudited Condensed Consolidated Statement of Comprehensive Income

Unaudited Condensed Consolidating Statement of Comprehensive Income

	Three months ended March 31, 2019
	Willis Towers Watson plc			Willis North America			Trinity Acquisition plc			Other guarantors			Non-guarantors			Eliminations			Consolidated
Revenue	$	—		$	22		$	—		$	—		$	2,290		$	—		$	2,312
Costs of providing services
Salaries and benefits		1			15			—			—			1,332			—			1,348
Other operating expenses		1			7			—			37			373			—			418
Depreciation		—			—			—			1			53			—			54
Amortization		—			—			—			1			126			—			127
Transaction and integration expenses		—			—			—			—			6			—			6
Total costs of providing services		2			22			—			39			1,890			—			1,953
(Loss)/income from operations		(2	)		—			—			(39	)		400			—			359
Intercompany (expense)/income		—			(12	)		23			66			(77	)		—			—
Interest expense		(7	)		(21	)		(22	)		—			(4	)		—			(54	)
Other income, net		—			—			—			—			55			—			55
(LOSS)/INCOME FROM OPERATIONS BEFORE INCOME TAXES		(9	)		(33	)		1			27			374			—			360
Benefit from/(provision for) income taxes		—			7			(1	)		(4	)		(69	)		—			(67	)
Equity account for subsidiaries		296			67			221			270			—			(854	)		—
NET INCOME		287			41			221			293			305			(854	)		293
Income attributable to non-controlling interests		—			—			—			—			(6	)		—			(6	)
NET INCOME ATTRIBUTABLE TO WILLIS TOWERS WATSON	$	287		$	41		$	221		$	293		$	299		$	(854	)	$	287

Comprehensive income before non- controlling interests	$	311		$	19		$	204		$	317		$	298		$	(834	)	$	315
Comprehensive income attributable to non- controlling interests		—			—			—			—			(5	)		—			(5	)
Comprehensive income attributable to Willis Towers Watson	$	311		$	19		$	204		$	317		$	293		$	(834	)	$	310

Unaudited Condensed Consolidating Statement of Comprehensive Income

	Three months ended March 31, 2018
	Willis Towers Watson plc			Willis North America			Trinity Acquisition plc			Other guarantors			Non-guarantors			Eliminations			Consolidated
Revenue	$	—		$	6		$	—		$	—		$	2,286		$	—		$	2,292
Costs of providing services
Salaries and benefits		1			15			—			—			1,361			—			1,377
Other operating expenses		—			5			—			42			376			—			423
Depreciation		—			—			—			1			48			—			49
Amortization		—			—			—			1			140			—			141
Transaction and integration expenses		—			5			—			1			37			—			43
Total costs of providing services		1			25			—			45			1,962			—			2,033
(Loss)/income from operations		(1	)		(19	)		—			(45	)		324			—			259
Intercompany (expense)/income		—			(5	)		30			92			(117	)		—			—
Interest expense		(7	)		(11	)		(27	)		—			(6	)		—			(51	)
Other income, net		—			—			—			1			55			—			56
(LOSS)/INCOME FROM OPERATIONS BEFORE INCOME TAXES		(8	)		(35	)		3			48			256			—			264
Benefit from/(provision for) income taxes		—			5			(1	)		(8	)		(39	)		—			(43	)
Equity account for subsidiaries		223			(7	)		142			181			—			(539	)		—
NET INCOME/(LOSS)		215			(37	)		144			221			217			(539	)		221
Income attributable to non-controlling interests		—			—			—			—			(6	)		—			(6	)
NET INCOME/(LOSS) ATTRIBUTABLE TO WILLIS TOWERS WATSON	$	215		$	(37	)	$	144		$	221		$	211		$	(539	)	$	215

Comprehensive income/(loss) before non- controlling interests	$	298		$	(22	)	$	226		$	303		$	338		$	(838	)	$	305
Comprehensive income attributable to non- controlling interests		—			—			—			—			(7	)		—			(7	)
Comprehensive income/(loss) attributable to Willis Towers Watson	$	298		$	(22	)	$	226		$	303		$	331		$	(838	)	$	298

Unaudited Condensed Consolidated Balance Sheet

Unaudited Condensed Consolidating Balance Sheet

	As of March 31, 2019
	Willis Towers Watson plc		Willis North America		Trinity Acquisition plc		Other guarantors		Non-guarantors		Eliminations			Consolidated
ASSETS
Cash and cash equivalents	$	—	$	—	$	—	$	—	$	992	$	—		$	992
Fiduciary assets		—		—		—		—		15,129		—			15,129
Accounts receivable, net		—		28		—		—		2,462		—			2,490
Prepaid and other current assets		—		371		1		30		338		(331	)		409
Total current assets		—		399		1		30		18,921		(331	)		19,020
Intercompany receivables, net		4,733		—		1,452		—		—		(6,185	)		—
Fixed assets, net		—		—		—		17		940		—			957
Goodwill		—		—		—		—		10,456		—			10,456
Other intangible assets, net		—		—		—		57		3,187		(57	)		3,187
Right-of-use assets		—		—		—		—		946		—			946
Pension benefits assets		—		—		—		—		833		—			833
Other non-current assets		—		142		2		48		420		(118	)		494
Total non-current assets		4,733		142		1,454		122		16,782		(6,360	)		16,873
Investments in subsidiaries		5,952		6,401		2,526		7,947		—		(22,826	)		—
TOTAL ASSETS	$	10,685	$	6,942	$	3,981	$	8,099	$	35,703	$	(29,517	)	$	35,893
LIABILITIES AND EQUITY
Fiduciary liabilities	$	—	$	—	$	—	$	—	$	15,129	$	—		$	15,129
Deferred revenue and accrued expenses		—		—		—		3		1,237		—			1,240
Current debt		—		187		—		—		—		—			187
Current lease liabilities		—		—		—		—		158		—			158
Other current liabilities		97		28		19		5		1,070		(279	)		940
Total current liabilities		97		215		19		8		17,594		(279	)		17,654
Intercompany payables, net		—		748		—		4,709		728		(6,185	)		—
Long-term debt		498		1,655		2,364		—		1		—			4,518
Liability for pension benefits		—		—		—		—		1,135		—			1,135
Deferred tax liabilities		—		—		—		—		662		(118	)		544
Provision for liabilities		—		120		—		—		423		—			543
Long-term lease liabilities		—		—		—		—		961		—			961
Other non-current liabilities		—		16		—		2		278		—			296
Total non-current liabilities		498		2,539		2,364		4,711		4,188		(6,303	)		7,997
TOTAL LIABILITIES		595		2,754		2,383		4,719		21,782		(6,582	)		25,651
REDEEMABLE NON-CONTROLLING INTEREST		—		—		—		—		28		—			28
EQUITY
Total Willis Towers Watson shareholders’ equity		10,090		4,188		1,598		3,380		13,771		(22,935	)		10,092
Non-controlling interests		—		—		—		—		122		—			122
Total equity		10,090		4,188		1,598		3,380		13,893		(22,935	)		10,214
TOTAL LIABILITIES AND EQUITY	$	10,685	$	6,942	$	3,981	$	8,099	$	35,703	$	(29,517	)	$	35,893

Unaudited Condensed Consolidating Balance Sheet

	As of December 31, 2018
	Willis Towers Watson plc		Willis North America		Trinity Acquisition plc		Other guarantors		Non-guarantors		Eliminations			Consolidated
ASSETS
Cash and cash equivalents	$	—	$	—	$	—	$	—	$	1,033	$	—		$	1,033
Fiduciary assets		—		—		—		—		12,604		—			12,604
Accounts receivable, net		—		24		—		—		2,355		—			2,379
Prepaid and other current assets		—		311		1		33		357		(298	)		404
Total current assets		—		335		1		33		16,349		(298	)		16,420
Intercompany receivables, net		4,755		—		1,355		—		—		(6,110	)		—
Fixed assets, net		—		—		—		16		926		—			942
Goodwill		—		—		—		—		10,465		—			10,465
Other intangible assets, net		—		—		—		58		3,318		(58	)		3,318
Pension benefits assets		—		—		—		—		773		—			773
Other non-current assets		—		92		2		49		452		(128	)		467
Total non-current assets		4,755		92		1,357		123		15,934		(6,296	)		15,965
Investments in subsidiaries		5,691		6,649		2,677		8,108		—		(23,125	)		—
TOTAL ASSETS	$	10,446	$	7,076	$	4,035	$	8,264	$	32,283	$	(29,719	)	$	32,385
LIABILITIES AND EQUITY
Fiduciary liabilities	$	—	$	—	$	—	$	—	$	12,604	$	—		$	12,604
Deferred revenue and accrued expenses		1		2		—		3		1,641		—			1,647
Current debt		—		186		—		—		—		—			186
Other current liabilities		95		38		33		13		935		(250	)		864
Total current liabilities		96		226		33		16		15,180		(250	)		15,301
Intercompany payables, net		—		902		—		4,691		517		(6,110	)		—
Long-term debt		498		1,635		2,256		—		—		—			4,389
Liability for pension benefits		—		—		—		—		1,170		—			1,170
Deferred tax liabilities		—		—		—		—		688		(129	)		559
Provision for liabilities		—		120		—		—		420		—			540
Other non-current liabilities		—		13		—		5		411		—			429
Total non-current liabilities		498		2,670		2,256		4,696		3,206		(6,239	)		7,087
TOTAL LIABILITIES		594		2,896		2,289		4,712		18,386		(6,489	)		22,388
REDEEMABLE NON-CONTROLLING INTEREST		—		—		—		—		26		—			26
EQUITY
Total Willis Towers Watson shareholders’ equity		9,852		4,180		1,746		3,552		13,752		(23,230	)		9,852
Non-controlling interests		—		—		—		—		119		—			119
Total equity		9,852		4,180		1,746		3,552		13,871		(23,230	)		9,971
TOTAL LIABILITIES AND EQUITY	$	10,446	$	7,076	$	4,035	$	8,264	$	32,283	$	(29,719	)	$	32,385

Unaudited Condensed Consolidated Statement of Cash Flows

Unaudited Condensed Consolidating Statement of Cash Flows

	Three months ended March 31, 2019
	Willis Towers Watson plc			Willis North America			Trinity Acquisition plc			Other guarantors			Non-guarantors			Eliminations			Consolidated
NET CASH FROM/(USED IN) OPERATING ACTIVITIES	$	38		$	(130	)	$	(31	)	$	(82	)	$	158		$	—		$	(47	)
CASH FLOWS FROM/(USED IN) INVESTING ACTIVITIES
Additions to fixed assets and software for internal use		—			—			—			(1	)		(56	)		—			(57	)
Capitalized software costs		—			—			—			—			(17	)		—			(17	)
Acquisitions of operations, net of cash acquired		—			—			—			—			(1	)		—			(1	)
Proceeds from/(repayments of) intercompany investing activities, net		17			111			(137	)		78			(34	)		(35	)		—
Net cash from/(used in) investing activities	$	17		$	111		$	(137	)	$	77		$	(108	)	$	(35	)	$	(75	)
CASH FLOWS (USED IN)/FROM FINANCING ACTIVITIES
Net payments on revolving credit facility		—			20			118			—			—			—			138
Repayments of debt		—			—			—			—			(1	)		—			(1	)
Proceeds from issuance of shares		22			—			—			—			—			—			22
Dividends paid		(77	)		—			—			—			—			—			(77	)
(Repayments of)/proceeds from intercompany financing activities, net		—			(1	)		50			5			(89	)		35			—
Net cash (used in)/from financing activities	$	(55	)	$	19		$	168		$	5		$	(90	)	$	35		$	82
DECREASE IN CASH AND CASH EQUIVALENTS		—			—			—			—			(40	)		—			(40	)
Effect of exchange rate changes on cash and cash equivalents		—			—			—			—			(1	)		—			(1	)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD		—			—			—			—			1,033			—			1,033
CASH AND CASH EQUIVALENTS, END OF PERIOD	$	—		$	—		$	—		$	—		$	992		$	—		$	992

Unaudited Condensed Consolidating Statement of Cash Flows

	Three months ended March 31, 2018
	Willis Towers Watson plc			Willis North America			Trinity Acquisition plc			Other guarantors			Non-guarantors			Eliminations			Consolidated
NET CASH FROM/(USED IN) OPERATING ACTIVITIES	$	72		$	(98	)	$	(196	)	$	245		$	328		$	(333	)	$	18
CASH FLOWS (USED IN)/FROM INVESTING ACTIVITIES
Additions to fixed assets and software for internal use		—			—			—			(1	)		(64	)		—			(65	)
Capitalized software costs		—			—			—			—			(13	)		—			(13	)
Acquisitions of operations, net of cash acquired		—			—			—			—			(5	)		—			(5	)
Net proceeds from sale of operations		—			—			—			—			4			—			4
(Repayments of)/proceeds from intercompany investing activities, net		(17	)		67			326			63			(195	)		(244	)		—
Net cash (used in)/from investing activities	$	(17	)	$	67		$	326		$	62		$	(273	)	$	(244	)	$	(79	)
CASH FLOWS (USED IN)/FROM FINANCING ACTIVITIES
Net borrowings on revolving credit facility		—			55			6			—			—			—			61
Repayments of debt		—			—			—			—			(21	)		—			(21	)
Proceeds from issuance of shares		11			—			—			—			—			—			11
Cash paid for employee taxes on withholding shares		—			—			—			—			(7	)		—			(7	)
Dividends paid		(68	)		—			(332	)		(1	)		—			333			(68	)
(Repayments of)/proceeds from intercompany financing activities, net		—			(24	)		196			(306	)		(110	)		244			—
Net cash (used in)/from financing activities	$	(57	)	$	31		$	(130	)	$	(307	)	$	(138	)	$	577		$	(24	)
DECREASE IN CASH AND CASH EQUIVALENTS		(2	)		—			—			—			(83	)		—			(85	)
Effect of exchange rate changes on cash and cash equivalents		—			—			—			—			9			—			9
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD		2			—			—			1			1,027			—			1,030
CASH AND CASH EQUIVALENTS, END OF PERIOD	$	—		$	—		$	—		$	1		$	953		$	—		$	954

Basis of Presentation and Recent Accounting Pronouncements - Narrative (Details) $ in Millions	Mar. 31, 2019 Country	Jan. 01, 2019 USD ($)
Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Reclassification between AOCL and retained earning \| $		$ 36
Number of countries in which entity operates (more than 140) \| Country	140
Percentage of lease denominated in U.S. dollars, Pounds Sterling or Euros	90.00%
Minimum [Member]
Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Real estate lease term	5 years
Maximum [Member]
Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Real estate lease term	15 years

Acquisitions - Narrative (Details) - USD ($) $ in Millions	Mar. 30, 2019	Dec. 21, 2018	Mar. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Other intangible assets, net			$ 3,187	$ 3,318
Goodwill			$ 10,456	$ 10,465
TRANZACT Acquisition [Member]
Business Acquisition [Line Items]
Business acquisition, date of acquisition agreement	Mar. 30, 2019
Total consideration to be transferred	$ 1,200
Business combination, consideration to be transferred in cash or ordinary shares	100
Business combination, contingent consideration arrangements, range of outcomes, value, high	$ 200
Alston Gayler Acquisition [Member]
Business Acquisition [Line Items]
Total consideration		$ 67
Consideration paid in cash		35
Deferred consideration		32
Other intangible assets, net		36
Goodwill		$ 24

Revenue - Schedule of Disaggregation of Revenue (Details) - USD ($)
$ in Millions

3 Months Ended

Mar. 31, 2019

Mar. 31, 2018

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

$ 2,286

$ 2,274

Interest and other income

^[1]

Revenues

2,312

2,292

Broking [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

1,141

1,135

Consulting [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

^[2]

728

741

Outsourced administration [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

^[2]

284

273

Other [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

^[2]

107

106

Operating Segments [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

2,260

2,255

Revenues

2,281

2,268

Segment Reconciling Items [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

^[3]

Revenues

HCB [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

837

842

Interest and other income

^[1]

Revenues

843

846

HCB [Member] | Broking [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

HCB [Member] | Consulting [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

^[2]

580

577

HCB [Member] | Outsourced administration [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

^[2]

123

132

HCB [Member] | Other [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

^[2]

HCB [Member] | Operating Segments [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

823

828

Revenues

829

832

HCB [Member] | Segment Reconciling Items [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

^[3]

BDA [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

138

124

Revenues

138

124

BDA [Member] | Broking [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

BDA [Member] | Outsourced administration [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

^[2]

132

118

BDA [Member] | Operating Segments [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

135

122

Revenues

135

122

BDA [Member] | Segment Reconciling Items [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

^[3]

CRB [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

719

734

Interest and other income

^[1]

Revenues

728

740

CRB [Member] | Broking [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

660

664

CRB [Member] | Consulting [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

^[2]

CRB [Member] | Outsourced administration [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

^[2]

CRB [Member] | Other [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

^[2]

CRB [Member] | Operating Segments [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

719

734

Revenues

728

740

Corporate, Non-Segment [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

Interest and other income

^[1]

Revenues

Corporate, Non-Segment [Member] | Consulting [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

^[2]

Corporate, Non-Segment [Member] | Other [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

^[2]

Corporate, Non-Segment [Member] | Operating Segments [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

Corporate, Non-Segment [Member] | Segment Reconciling Items [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

^[3]

IRR [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

581

569

Interest and other income

^[1]

Revenues

591

576

IRR [Member] | Broking [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

405

391

IRR [Member] | Consulting [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

^[2]

114

117

IRR [Member] | Outsourced administration [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

^[2]

IRR [Member] | Other [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

^[2]

IRR [Member] | Operating Segments [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

579

567

Revenues

589

574

IRR [Member] | Segment Reconciling Items [Member]

Disaggregation Of Revenue [Line Items]

Revenue from Contract with Customer, Excluding Assessed Tax

^[3]

$ 2

[1]	Interest and other income is included in segment revenue and total revenue, however it has been presented separately in the above tables because it does not arise directly from contracts with customers.
[2]	Amounts presented for HCB Outsourced administration revenue include a correction of approximately $58 million of revenue that was previously classified as HCB Consulting revenue or HCB Other revenue in our quarterly report on Form 10-Q for the three months ended March 31, 2018.
[3]	Reimbursable expenses and other, as well as Corporate revenue, are excluded from segment revenue, but included in total revenue on the condensed consolidated statements of comprehensive income.

Revenue - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
Revenue - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2019	Mar. 31, 2018
December 31, 2018 [Member]
Disaggregation Of Revenue [Line Items]
Contract with Customer, Liability, Revenue Recognized	$ 242
Other [Member] \| Maximum [Member]
Disaggregation Of Revenue [Line Items]
Revenue, Percentage of Total Revenue	5.00%	5.00%

Revenue - Schedule of Contract Balances (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Revenue From Contract With Customer [Abstract]
Billed Receivable, Current	$ 1,847	$ 1,702
Unbilled Receivable, Current	396	356
Contract asset, Current	247	321
Accounts receivable, net	2,490	2,379
Non-current accounts receivable, net	17	20
Contract asset, Noncurrent	6	3
Deferred revenue	$ 483	$ 448

Revenue - Schedule of Remaining Performance Obligations (Details) $ in Millions	Mar. 31, 2019 USD ($)
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation	$ 1,087
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-04-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation	$ 314
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	9 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation	$ 341
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation	$ 432
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period

Segment Information - Narrative (Details)	3 Months Ended
Segment Information - Narrative (Details)	Mar. 31, 2019 segment
Segment Reporting [Abstract]
Number of operating segments	4
Number of reportable segments	4

Segment Information - Revenue (Net of Reimbursable Expenses) of the Reported Segments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Revenues	$ 2,312	$ 2,292
Income from operations	359	259
HCB [Member]
Segment Reporting Information [Line Items]
Revenues	843	846
CRB [Member]
Segment Reporting Information [Line Items]
Revenues	728	740
IRR [Member]
Segment Reporting Information [Line Items]
Revenues	591	576
BDA [Member]
Segment Reporting Information [Line Items]
Revenues	138	124
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues	2,281	2,268
Income from operations	562	547
Operating Segments [Member] \| HCB [Member]
Segment Reporting Information [Line Items]
Revenues	829	832
Income from operations	204	193
Operating Segments [Member] \| CRB [Member]
Segment Reporting Information [Line Items]
Revenues	728	740
Income from operations	127	125
Operating Segments [Member] \| IRR [Member]
Segment Reporting Information [Line Items]
Revenues	589	574
Income from operations	252	261
Operating Segments [Member] \| BDA [Member]
Segment Reporting Information [Line Items]
Revenues	135	122
Income from operations	$ (21)	$ (32)

Segment Information - Reconciliation of Information Reported by Segment to Condensed Consolidated Statement of Comprehensive Income Amounts (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue:
Revenue	$ 2,312	$ 2,292
Income/(loss) from operations	359	259
Amortization	(127)	(141)
Interest expense	(54)	(51)
Other income, net	55	56
INCOME FROM OPERATIONS BEFORE INCOME TAXES	360	264
Operating Segments [Member]
Revenue:
Revenue	2,281	2,268
Income/(loss) from operations	562	547
Segment Reconciling Items [Member]
Revenue:
Revenue	31	24
Amortization	(127)	(141)
Transaction and integration expenses	(6)	(43)
Unallocated, net	(70)	(104)
Interest expense	(54)	(51)
Other income, net	$ 55	$ 56

Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
Income Taxes - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2019	Mar. 31, 2018
Operating Loss Carryforwards [Line Items]
Provision for income taxes	$ 67	$ 43
Effective tax rate	18.80%	16.30%
Liabilities for uncertain tax positions	$ 48
Minimum [Member]
Operating Loss Carryforwards [Line Items]
Expected decrease in liability for uncertain tax position	1
Maximum [Member]
Operating Loss Carryforwards [Line Items]
Expected decrease in liability for uncertain tax position	$ 3

Goodwill and Other Intangible Assets - Components of Goodwill (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	$ 10,957
Accumulated impairment losses, beginning balance	(492)
Goodwill, net, beginning balance	10,465
Foreign exchange	(9)
Goodwill, gross, ending balance	10,948
Accumulated impairment losses, ending balance	(492)
Goodwill, net, ending balance	10,456
HCB [Member]
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	4,300
Accumulated impairment losses, beginning balance	(130)
Goodwill, net, beginning balance	4,170
Foreign exchange	(6)
Goodwill, gross, ending balance	4,294
Accumulated impairment losses, ending balance	(130)
Goodwill, net, ending balance	4,164
CRB [Member]
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	2,308
Accumulated impairment losses, beginning balance	(362)
Goodwill, net, beginning balance	1,946
Foreign exchange	(7)
Goodwill, gross, ending balance	2,301
Accumulated impairment losses, ending balance	(362)
Goodwill, net, ending balance	1,939
IRR [Member]
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	1,792
Accumulated impairment losses, beginning balance	0
Goodwill, net, beginning balance	1,792
Foreign exchange	4
Goodwill, gross, ending balance	1,796
Accumulated impairment losses, ending balance	0
Goodwill, net, ending balance	1,796
BDA [Member]
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	2,557
Accumulated impairment losses, beginning balance	0
Goodwill, net, beginning balance	2,557
Foreign exchange	0
Goodwill, gross, ending balance	2,557
Accumulated impairment losses, ending balance	0
Goodwill, net, ending balance	$ 2,557

Goodwill and Other Intangible Assets - Finite-Lived Intangible Assets and Liabilities (Details) - USD ($)
$ in Millions

3 Months Ended

Mar. 31, 2019

Mar. 31, 2018

Dec. 31, 2018

Finite-lived Intangible Assets [Roll Forward]

Balance at December 31, 2018

$ 3,318

Intangible assets acquired

Intangible assets disposed

(1)

ASC 842 reclassification

^[1]

(9)

Amortization

(127)

$ (141)

Foreign exchange

Balance at March 31, 2019

3,187

Finite-lived intangible assets, gross carrying amount

5,309

$ 5,318

Finite-lived intangible assets, accumulated amortization

(2,122)

(2,000)

Finite-lived intangible liabilities, gross carrying amount

Finite-lived intangible liabilities, accumulated amortization

(13)

Client relationships [Member]

Finite-lived Intangible Assets [Roll Forward]

Balance at December 31, 2018

1,986

Intangible assets acquired

Intangible assets disposed

(1)

ASC 842 reclassification

^[1]

Amortization

(82)

Foreign exchange

Balance at March 31, 2019

1,909

Finite-lived intangible assets, gross carrying amount

3,405

3,401

Finite-lived intangible assets, accumulated amortization

(1,496)

(1,415)

Management contracts [Member]

Finite-lived Intangible Assets [Roll Forward]

Balance at December 31, 2018

Intangible assets acquired

Intangible assets disposed

ASC 842 reclassification

^[1]

Amortization

(1)

Foreign exchange

(2)

Balance at March 31, 2019

Finite-lived intangible assets, gross carrying amount

Finite-lived intangible assets, accumulated amortization

(15)

Software [Member]

Finite-lived Intangible Assets [Roll Forward]

Balance at December 31, 2018

328

Intangible assets acquired

Intangible assets disposed

ASC 842 reclassification

^[1]

Amortization

(32)

Foreign exchange

Balance at March 31, 2019

298

Finite-lived intangible assets, gross carrying amount

754

749

Finite-lived intangible assets, accumulated amortization

(456)

(421)

Trademark and trade name [Member]

Finite-lived Intangible Assets [Roll Forward]

Balance at December 31, 2018

920

Intangible assets acquired

Intangible assets disposed

ASC 842 reclassification

^[1]

Amortization

(11)

Foreign exchange

Balance at March 31, 2019

909

Finite-lived intangible assets, gross carrying amount

1,052

Finite-lived intangible assets, accumulated amortization

(143)

(132)

Product [Member]

Finite-lived Intangible Assets [Roll Forward]

Balance at December 31, 2018

Intangible assets acquired

Intangible assets disposed

ASC 842 reclassification

^[1]

Amortization

(1)

Foreign exchange

Balance at March 31, 2019

Finite-lived intangible assets, gross carrying amount

Finite-lived intangible assets, accumulated amortization

(10)

(9)

Favorable agreements [Member]

Finite-lived Intangible Assets [Roll Forward]

Balance at December 31, 2018

Intangible assets acquired

Intangible assets disposed

ASC 842 reclassification

^[1]

(9)

Amortization

Foreign exchange

Balance at March 31, 2019

Finite-lived intangible assets, gross carrying amount

^[2]

Finite-lived intangible assets, accumulated amortization

^[2]

(5)

Other Intangible Assets

Finite-lived Intangible Assets [Roll Forward]

Finite-lived intangible assets, gross carrying amount

Finite-lived intangible assets, accumulated amortization

(2)

(3)

Unfavorable agreements [Member]

Finite-lived Intangible Assets [Roll Forward]

Finite-lived intangible liabilities, gross carrying amount

^[2]

Finite-lived intangible liabilities, accumulated amortization

^[2]

$ 0

$ (13)

[1]	On January 1, 2019, in accordance with ASC 842, we reclassified our favorable lease agreement assets to right-of-use assets within our condensed consolidated balance sheet.
[2]	On January 1, 2019, in accordance with ASC 842, we reclassified our favorable lease agreement assets and unfavorable lease agreement liabilities to right-of-use assets and as reductions to right-of-use assets, respectively, within our condensed consolidated balance sheet.

Goodwill and Other Intangible Assets - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Finite-lived Intangible Assets [Roll Forward]
Amortization	$ (127)	$ (141)
Acquired unfavorable lease agreement liabilities, net			$ 21
Weighted average remaining life of amortizable intangible assets	13 years 9 months 18 days

Goodwill and Other Intangible Assets - Schedule of Future Amortization Expense (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Remainder of 2019	$ 353
2020	424
2021	347
2022	288
2023	239
Thereafter	1,536
Total	$ 3,187	$ 3,318

Derivative Financial Instruments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Derivative [Line Items]
Loss on derivatives to be reclassified within the next twelve months	$ (2)
Maximum [Member]
Derivative [Line Items]
Longest outstanding maturity	1 year 8 months 12 days
Not Designated as Hedging Instrument [Member] \| Foreign exchange contracts [Member]
Derivative [Line Items]
Derivative, notional amount	$ 890		$ 909
Derivative liability, fair value	7
Derivative asset, fair value			3
Not Designated as Hedging Instrument [Member] \| Foreign exchange contracts [Member] \| Other income, net [Member]
Derivative [Line Items]
Loss recognized in income	(10)	$ (5)
Cash Flow Hedging \| Designated as Hedging Instrument
Derivative [Line Items]
Gain/(loss) reclassified from Accumulated OCL into income (effective element)	(4)	(11)
Cash Flow Hedging \| Designated as Hedging Instrument \| Revenue [Member]
Derivative [Line Items]
Gain/(loss) reclassified from Accumulated OCL into income (effective element)	1
Cash Flow Hedging \| Designated as Hedging Instrument \| Salaries and Benfits [Member]
Derivative [Line Items]
Gain/(loss) reclassified from Accumulated OCL into income (effective element)	(5)
Cash Flow Hedging \| Designated as Hedging Instrument \| Other Income, Net [Member]
Derivative [Line Items]
Gain/(loss) reclassified from Accumulated OCL into income (effective element)		(11)
Cash Flow Hedging \| Designated as Hedging Instrument \| Foreign exchange contracts [Member]
Derivative [Line Items]
Derivative, notional amount	414		438
Derivative liability, fair value	3		$ 15
Gain recognized in OCI (effective element)	$ 8	$ 15

Debt - Schedule of Long-term Debt (Details)
€ in Millions

3 Months Ended

Mar. 31, 2019

USD ($)

Mar. 31, 2019

EUR (€)

Dec. 31, 2018

USD ($)

Debt Instrument [Line Items]

Current debt

$ 187,000,000

$ 186,000,000

Long-term debt, excluding current maturities

4,518,000,000

4,389,000,000

7.000% senior notes due 2019 [Member]

Debt Instrument [Line Items]

Current debt

$ 187,000,000

186,000,000

Stated interest rate

7.00%

Debt instrument maturity year

2019

Revolving 1.25 Billion Dollar Credit Facility [Member]

Debt Instrument [Line Items]

Long-term debt, excluding current maturities

$ 269,000,000

130,000,000

Revolving 1.25 Billion Dollar Credit Facility [Member] | Revolving Credit Facility [Member]

Debt Instrument [Line Items]

Maximum borrowing capacity

1,250,000,000

5.750% senior notes due 2021 [Member]

Debt Instrument [Line Items]

Long-term debt, excluding current maturities

$ 498,000,000

498,000,000

Stated interest rate

5.75%

Debt instrument maturity year

2021

3.500% senior notes due 2021 [Member]

Debt Instrument [Line Items]

Long-term debt, excluding current maturities

$ 448,000,000

448,000,000

Stated interest rate

3.50%

Debt instrument maturity year

2021

2.125% senior notes due 2022 [Member]

Debt Instrument [Line Items]

Long-term debt, excluding current maturities

$ 604,000,000

^[1]

€ 540

615,000,000

^[1]

Stated interest rate

^[1]

2.125%

Debt instrument maturity year

^[1]

2022

4.625% senior notes due 2023 [Member]

Debt Instrument [Line Items]

Long-term debt, excluding current maturities

$ 248,000,000

248,000,000

Stated interest rate

4.625%

Debt instrument maturity year

2023

3.600% senior notes due 2024 [Member]

Debt Instrument [Line Items]

Long-term debt, excluding current maturities

$ 646,000,000

645,000,000

Stated interest rate

3.60%

Debt instrument maturity year

2024

4.400% senior notes due 2026 [Member]

Debt Instrument [Line Items]

Long-term debt, excluding current maturities

$ 544,000,000

544,000,000

Stated interest rate

4.40%

Debt instrument maturity year

2026

4.500% senior notes due 2028 [Member]

Debt Instrument [Line Items]

Long-term debt, excluding current maturities

$ 595,000,000

595,000,000

Stated interest rate

4.50%

Debt instrument maturity year

2028

6.125% senior notes due 2043 [Member]

Debt Instrument [Line Items]

Long-term debt, excluding current maturities

$ 271,000,000

271,000,000

Stated interest rate

6.125%

Debt instrument maturity year

2043

5.050% senior notes due 2048 [Member]

Debt Instrument [Line Items]

Long-term debt, excluding current maturities

$ 395,000,000

Stated interest rate

5.05%

Debt instrument maturity year

2048

[1]	Notes issued in Euro (€540 million)

Debt - Narrative (Details)	3 Months Ended
Debt - Narrative (Details)	Mar. 31, 2019 USD ($)
Debt Instrument [Line Items]
Debt Instrument Commitment Fee Percentage	0.15%
Federal Funds Effective Swap Rate [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.50%
London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.00%
Maximum [Member] \| Eurodollar [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.375%
Maximum [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt Instrument Additional Basis Spread On Variable Rate1	0.375%
Minimum [Member] \| Eurodollar [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.75%
Minimum [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt Instrument Additional Basis Spread On Variable Rate1	0.00%
Term Loan [Member]
Debt Instrument [Line Items]
Debt instrument, term	1 year
Debt Instrument, Interest Rate Terms	Amounts outstanding under the term loan shall bear interest, at the option of the borrowers, at a rate equal to (a) LIBOR plus 0.75% to 1.375% for Eurocurrency Rate Loans or (b) the highest of (i) the Federal Funds Rate plus 0.5%, (ii) the ‘prime rate’ quoted by Bank of America, N.A., and (iii) LIBOR plus 1.00%, plus 0.00% to 0.375%,
Term Loan [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 1,100,000,000

Fair Value Measurements - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) $ in Millions	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Contingent consideration [Member] \| Fair Value Inputs, Discount Rate [Member]
Liabilities:
Fair Value Inputs, Discount Rate	9.90	9.92
Recurring [Member]
Assets:
Mutual funds / exchange traded funds	$ 19	$ 18
Derivative financial instruments	4	5
Liabilities:
Contingent consideration	55	51
Derivative financial instruments	14	17
Recurring [Member] \| Level 1 [Member]
Assets:
Mutual funds / exchange traded funds	19	18
Derivative financial instruments	0	0
Liabilities:
Contingent consideration	0	0
Derivative financial instruments	0	0
Recurring [Member] \| Level 2 [Member]
Assets:
Mutual funds / exchange traded funds	0	0
Derivative financial instruments	4	5
Liabilities:
Contingent consideration	0	0
Derivative financial instruments	14	17
Recurring [Member] \| Level 3 [Member]
Assets:
Mutual funds / exchange traded funds	0	0
Derivative financial instruments	0	0
Liabilities:
Contingent consideration	55	51
Derivative financial instruments	$ 0	$ 0

Fair Value Measurements - Fair Value Liabilities Measured Using Significant Unobservable Inputs Level 3 (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance as of beginning of period	$ 51
Obligations assumed	4
Payments	(1)
Realized and unrealized gains	0
Foreign exchange	1
Balance as of end of period	$ 55

Fair Value Measurements - Schedule of Liabilities Whose Carrying Values Differ From the Fair Value and are Not Measured on a Recurring Basis (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Current debt	$ 187	$ 186
Long-term debt	4,518	4,389
Carrying Value [Member] \| Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Current debt	187	186
Long-term debt	4,518	4,389
Fair Value [Member] \| Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Current debt	190	191
Long-term debt	$ 4,721	$ 4,458

Retirement Benefits - Narrative (Details) - USD ($)	3 Months Ended
Retirement Benefits - Narrative (Details) - USD ($)	Mar. 31, 2019	Mar. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Portion of pension and OPEB obligation attributed to disclosed plans (as a percent)	99.00%
Defined contribution plan, employer contribution	$ 41,000,000	$ 48,000,000
Pension Plan [Member] \| UNITED STATES [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit pension plans contributions	0
Defined benefit plan, estimated future employer additional contributions, remainder of fiscal year	60,000,000
Pension Plan [Member] \| UNITED KINGDOM [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit pension plans contributions	18,000,000
Defined benefit plan, estimated future employer additional contributions, remainder of fiscal year	58,000,000
Pension Plan [Member] \| Other Foreign Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit pension plans contributions	15,000,000
Defined benefit plan, estimated future employer additional contributions, remainder of fiscal year	$ 7,000,000

Retirement Benefits - Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Pension Plan [Member] \| UNITED STATES [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 16	$ 16
Interest cost	40	35
Expected return on plan assets	(64)	(68)
Amortization of net loss	5	3
Amortization of prior service credit	0	0
Net periodic benefit (income)/cost	(3)	(14)
Pension Plan [Member] \| UNITED KINGDOM [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	4	5
Interest cost	24	24
Expected return on plan assets	(63)	(78)
Amortization of net loss	5	12
Amortization of prior service credit	(4)	(5)
Net periodic benefit (income)/cost	(34)	(42)
Pension Plan [Member] \| Other Foreign Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	5	5
Interest cost	4	5
Expected return on plan assets	(7)	(8)
Amortization of net loss	1	0
Amortization of prior service credit	0	0
Net periodic benefit (income)/cost	3	2
PRW [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0
Interest cost	1	1
Expected return on plan assets	0	0
Amortization of net loss	0	0
Amortization of prior service credit	(1)	0
Net periodic benefit (income)/cost	$ 0	$ 1

Leases - Narrative (Details) - USD ($) $ in Millions		3 Months Ended
Leases - Narrative (Details) - USD ($) $ in Millions	Jan. 01, 2019	Mar. 31, 2018	Mar. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Additional lease liabilities	$ 1,200		$ 1,119	$ 1,149
Right-of-use asset	1,000		$ 946
Deferred tax assets	252
Deferred tax liabilities	252
Adjustment of retained earnings	$ 0
Rent expense, net of sublease income		$ 64

Leases - Schedule of Lease (Details) - USD ($) $ in Millions	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Leases [Abstract]
Right-of-use assets	$ 946	$ 1,000
Operating Lease, Current lease liabilities	158
Operating Lease, Long-term lease liabilities	961
Finance Lease, Right-of-use assets	14
Finance Lease, Current lease liabilities	3
Finance Lease, Long-term lease liabilities	25		$ 26
Total Right-of-use assets	960
Total Current lease liabilities	161
Total Long-term lease liabilities	$ 986

Leases - Schedule of Amount Recorded in Condensed Consolidated Statement of Comprehensive Income (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Finance lease cost:
Amortization of right-of-use assets	$ 1
Interest on lease liabilities	1
Operating lease cost	48
Variable lease cost	13
Sublease income	(4)
Total lease cost, net	$ 59

Leases -Schedule of Cash Paid in the Measurement of Lease Liabilities (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Cash flows from operating activities:
Operating leases	$ 55
Finance leases	1
Cash flows from financing activities:
Finance leases	1
Total lease payments	$ 57

Leases - Schedule of Weighted Average Term and Discount Rates (Details)	Mar. 31, 2019
Leases [Abstract]
Operating Leases, Weighted-average remaining term	9 years 1 month 6 days
Operating Leases, Weighted-average discount rate	3.60%
Finance Leases, Weighted-average remaining term	6 years 9 months 18 days
Finance Leases, Weighted-average discount rate	12.90%

Leases - Schedule of Maturity of Operating and Finance Leases Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Operating Leases [Abstract]
Operating Lease, Remainder of 2019	$ 147
Operating Lease, 2020	180		$ 180
Operating Lease, 2021	160		159
Operating Lease, 2022	142		142
Operating Lease, 2023	132		131
Operating Lease, Thereafter	552		542
Operating Lease, Total future lease payments	1,313		1,351
Operating Lease, Interest	(194)		(202)
Operating Lease, Total lease liabilities	1,119	$ 1,200	1,149
Operating Leases, 2019			197
Additional lease liabilities	1,119	$ 1,200	1,149
Finance Leases [Abstract]
Finance Lease, Remainder of 2019	4
Finance Lease, 2020	6		6
Finance Lease, 2021	6		6
Finance Lease, 2022	6		6
Finance Lease, 2023	6		6
Finance Lease, Thereafter	14		14
Finance Lease, Total future lease payments	42		43
Finance Lease, Interest	(14)		(14)
Finance Lease, Total lease liabilities	28		29
Finance Lease, 2019			5
Leases Liabilities Due [Abstract]
Total Lease, Remainder of 2019	151
Total Lease, 2020	186		186
Total Lease, 2021	166		165
Total Lease, 2022	148		148
Total Lease, 2023	138		137
Total Lease, Thereafter	566		556
Total Lease, Total future lease payments	1,355		1,394
Total Lease, Interest	(208)		(216)
Total Lease, Total lease liabilities	$ 1,147		1,178
Total Lease, 2019			$ 202

Commitments and Contingencies - Narrative (Details)																	3 Months Ended		86 Months Ended
Commitments and Contingencies - Narrative (Details)	Sep. 12, 2016 USD ($) plaintiff	Aug. 05, 2016 USD ($) plaintiff	Mar. 31, 2016 USD ($)	Jul. 21, 2015	Jul. 15, 2015	Oct. 01, 2013 USD ($)	Jun. 20, 2013 lawsuit	Jun. 11, 2013 lawsuit	Jun. 03, 2013 lawsuit	Feb. 14, 2013 USD ($) lawsuit plaintiff	Feb. 08, 2013 USD ($) plaintiff	Apr. 01, 2011 USD ($)	Mar. 11, 2011 USD ($) plaintiff	Sep. 16, 2010 USD ($) plaintiff	Sep. 14, 2009 USD ($) plaintiff	Aug. 06, 2009 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 12, 2016 lawsuit	Mar. 25, 2014 action
Settled Litigation [Member] \| Stanford Financial Group [Member]
Loss Contingencies [Line Items]
Number of complaints filed \| lawsuit																			15
Provision for litigation losses																	$ 50,000,000	$ 70,000,000
Litigation settlement amount			$ 120,000,000														$ 120,000,000
Settled Litigation [Member] \| Troice, et al. v. Willis of Colorado, Inc., et al. [Member]
Loss Contingencies [Line Items]
Damages sought (in excess of)												$ 1,000,000,000
Number of actions consolidated \| action																				2
Settled Litigation [Member] \| Janvey, et al. v. Willis of Colorado, Inc., et al. [Member]
Loss Contingencies [Line Items]
Damages sought (in excess of)						$ 1,000,000,000
Total losses incurred by plaintiff						$ 4,600,000,000
Pending Litigation [Member] \| Canabal, et al. v. Willis of Colorado, Inc., et al. [Member]
Loss Contingencies [Line Items]
Damages sought (in excess of)																$ 1,000,000,000
Pending Litigation [Member] \| Rupert, et al. v. Winter, et al. [Member]
Loss Contingencies [Line Items]
Number of plaintiffs \| plaintiff															97
Damages sought (in excess of)															$ 300,000,000
Pending Litigation [Member] \| Casanova, et al. v. Willis of Colorado, Inc., et al. [Member]
Loss Contingencies [Line Items]
Number of plaintiffs \| plaintiff														7
Damages sought (in excess of)														$ 5,000,000
Pending Litigation [Member] \| Rishmague, et ano. v. Winter, et al. [Member]
Loss Contingencies [Line Items]
Number of plaintiffs \| plaintiff													2
Damages sought (in excess of)													$ 37,000,000
Pending Litigation [Member] \| MacArthur v. Winter, et al. [Member]
Loss Contingencies [Line Items]
Number of plaintiffs \| plaintiff											2
Damages sought (in excess of)											$ 4,000,000
Pending Litigation [Member] \| Stanford Financial Group, Florida Suits [Member]
Loss Contingencies [Line Items]
Number of complaints filed \| lawsuit										5
Number of cases removed \| lawsuit									5
Number of cases moved to stay \| lawsuit								4
Number of cases transferred \| lawsuit							5
Claims stayed, period							7 days
Pending Litigation [Member] \| Barbar, et al. v. Willis Group Holdings Public Limited Company, et al. [Member]
Loss Contingencies [Line Items]
Number of plaintiffs \| plaintiff										35
Damages sought (in excess of)										$ 30,000,000
Pending Litigation [Member] \| de Gadala-Maria, et al. v. Willis Group Holdings Public Limited Company, et al. [Member]
Loss Contingencies [Line Items]
Number of plaintiffs \| plaintiff										64
Damages sought (in excess of)										$ 83,500,000
Period to replead dismissed claim				21 days
Pending Litigation [Member] \| Ranni, et ano. v. Willis Group Holdings Public Limited Company, et al. [Member]
Loss Contingencies [Line Items]
Number of plaintiffs \| plaintiff										2
Damages sought (in excess of)										$ 3,000,000
Pending Litigation [Member] \| Tisminesky, et al. v. Willis Group Holdings Public Limited Company, et al. [Member]
Loss Contingencies [Line Items]
Number of plaintiffs \| plaintiff										11
Damages sought (in excess of)										$ 6,500,000
Period to replead dismissed claim				21 days
Pending Litigation [Member] \| Zacarias, et al. v. Willis Group Holdings Public Limited Company, et al. [Member]
Loss Contingencies [Line Items]
Number of plaintiffs \| plaintiff										10
Damages sought (in excess of)										$ 12,500,000
Period to replead dismissed claim					21 days
Pending Litigation [Member] \| Martin v. Willis of Colorado, Inc., et. al. [Member]
Loss Contingencies [Line Items]
Number of plaintiffs \| plaintiff	5	1
Damages sought (in excess of)	$ 1,000,000	$ 100,000
Pending Litigation [Member] \| Abel, et al. v. Willis of Colorado, Inc., et al [Member]
Loss Contingencies [Line Items]
Number of plaintiffs \| plaintiff	300
Damages sought (in excess of)	$ 135,000,000

Supplementary Information for Certain Balance Sheet Accounts - Deferred Revenue and Accrued Expenses (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Accounts payable, accrued liabilities and deferred income	$ 688	$ 691
Accrued discretionary and incentive compensation	327	758
Accrued vacation	143	111
Other employee-related liabilities	82	87
Total deferred revenue and accrued expenses	$ 1,240	$ 1,647

Supplementary Information for Certain Balance Sheet Accounts - Provision For Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Claims, lawsuits and other proceedings	$ 460	$ 455
Other provisions	83	85
Total provision for liabilities	$ 543	$ 540

Supplementary Information for Certain Balance Sheet Accounts - Other Non-current Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Incentives from lessors		$ 120
Deferred compensation plan liability	$ 132	125
Contingent and deferred consideration on acquisitions	25	22
Liabilities for uncertain tax positions	48	46
Finance leases	25	26
Other non-current liabilities	66	90
Total other non-current liabilities	$ 296	$ 429

Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions		3 Months Ended
	Jan. 01, 2019	Mar. 31, 2019	Mar. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Stockholders' equity attributable to parent, beginning balance	$ 9,852	$ 9,852
Reclassification of tax effects per ASU 2018-02	0
Stockholders' equity attributable to parent, ending balance		10,092
Foreign currency translation [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Stockholders' equity attributable to parent, beginning balance	(616)	(616)	$ (365)
Other comprehensive income/(loss) before reclassifications		9	58
Amounts reclassified from accumulated other comprehensive income/(loss) (net of income tax)		0	0
Net current-period other comprehensive income/(loss)		9	58
Stockholders' equity attributable to parent, ending balance		(607)	(307)
Foreign currency translation [Member] \| Accounting Standards Update 2018-02 [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification of tax effects per ASU 2018-02		0	0
Gains and losses on cash flow hedges [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Stockholders' equity attributable to parent, beginning balance	(8)	(8)	(10)
Other comprehensive income/(loss) before reclassifications		6	9
Amounts reclassified from accumulated other comprehensive income/(loss) (net of income tax)		5	10
Net current-period other comprehensive income/(loss)		11	19
Stockholders' equity attributable to parent, ending balance		3	9
Gains and losses on cash flow hedges [Member] \| Accounting Standards Update 2018-02 [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification of tax effects per ASU 2018-02		0	0
Defined pension and post-retirement benefit costs [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Stockholders' equity attributable to parent, beginning balance	(1,337)	(1,337)	(1,138)
Other comprehensive income/(loss) before reclassifications		1	(1)
Amounts reclassified from accumulated other comprehensive income/(loss) (net of income tax)		2	7
Net current-period other comprehensive income/(loss)		(33)	6
Stockholders' equity attributable to parent, ending balance		(1,370)	(1,132)
Defined pension and post-retirement benefit costs [Member] \| Accounting Standards Update 2018-02 [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification of tax effects per ASU 2018-02	36	(36)	0
AOCL [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Stockholders' equity attributable to parent, beginning balance	(1,961)	(1,961)	(1,513)
Other comprehensive income/(loss) before reclassifications		16	66
Amounts reclassified from accumulated other comprehensive income/(loss) (net of income tax)		7	17
Net current-period other comprehensive income/(loss)		(13)	83
Stockholders' equity attributable to parent, ending balance		(1,974)	(1,430)
AOCL [Member] \| Accounting Standards Update 2018-02 [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification of tax effects per ASU 2018-02		(36)	0
AOCL [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Stockholders' equity attributable to parent, beginning balance	$ (1,961)	(1,961)	(1,513)
Other comprehensive income/(loss) before reclassifications		16	66
Amounts reclassified from accumulated other comprehensive income/(loss) (net of income tax)		7	17
Net current-period other comprehensive income/(loss)		(13)	83
Stockholders' equity attributable to parent, ending balance		(1,974)	(1,430)
AOCL [Member] \| Accounting Standards Update 2018-02 [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification of tax effects per ASU 2018-02		$ (36)	$ 0

Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Income (Loss) (Parenthetical) (Details) - USD ($) $ in Millions		3 Months Ended
	Jan. 01, 2019	Mar. 31, 2019	Mar. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification from AOCI, Current Period, Tax		$ 1	$ 4
Adjustment of retained earnings	$ 0
Accounting Standards Update 2018-02 [Member] \| Defined pension and post-retirement benefit costs [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Adjustment of retained earnings	$ 36	$ (36)	$ 0

Earnings Per Share - Narrative (Details) - shares shares in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Restricted share units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Antidilutive securities excluded from computation of earnings per share	0.0	0.0
Time-based award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options outstanding	0.3	0.7
Restricted share units outstanding		0.1
Performance-based [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options outstanding	0.4	0.6
Restricted share units outstanding	0.5	0.7
Phantom Share Units (PSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted share units outstanding	0.3	0.0

Earnings Per Share - Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
NET INCOME ATTRIBUTABLE TO WILLIS TOWERS WATSON	$ 287	$ 215
Basic average number of shares outstanding (shares)	130	133
Dilutive effect of potentially issuable shares (shares)	0	0
Diluted average number of shares outstanding (shares)	130	133
Basic earnings per share	$ 2.21	$ 1.62
Dilutive effect of potentially issuable shares (USD per share)	(0.01)	(0.01)
Diluted earnings per share	$ 2.20	$ 1.61

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

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+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References

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+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Financial Information for Issuers and Other Guarantor Subsidiaries - Narrative (Details) € in Millions	Mar. 31, 2019 USD ($)	Sep. 10, 2018 USD ($)	May 16, 2017 USD ($)	Mar. 07, 2017 USD ($)	May 26, 2016 USD ($)	May 26, 2016 EUR (€)	Mar. 22, 2016 USD ($)	Aug. 15, 2013 USD ($)	Mar. 17, 2011 USD ($)	Sep. 29, 2009 USD ($)
Revolving Credit Facility [Member] \| Revolving 1.25 Billion Dollar Credit Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 1,250,000,000
Trinity Acquisition plc [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity				$ 1,250,000,000
Trinity Acquisition plc [Member] \| Revolving Credit Facility [Member] \| Revolving 1.25 Billion Dollar Credit Facility [Member]
Debt Instrument [Line Items]
Long-term debt	269,000,000
Senior Notes [Member] \| Willis North America [Member]
Debt Instrument [Line Items]
Long-term debt	1,800,000,000	$ 1,000,000,000.0	$ 650,000,000							$ 187,000,000
Senior Notes [Member] \| Trinity Acquisition plc [Member]
Debt Instrument [Line Items]
Long-term debt	$ 2,100,000,000				$ 609,000,000	€ 540	$ 1,000,000,000.0	$ 525,000,000
Parent Company [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Long-term debt									$ 500,000,000

Financial Information for Issuers and Other Guarantor Subsidiaries - Unaudited Condensed Consolidated Statement of Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Condensed Financial Statements, Captions [Line Items]
Revenue	$ 2,312	$ 2,292
Costs of providing services
Salaries and benefits	1,348	1,377
Other operating expenses	418	423
Depreciation	54	49
Amortization	127	141
Transaction and integration expenses	6	43
Total costs of providing services	1,953	2,033
Income from operations	359	259
Intercompany (expense)/income	0	0
Interest expense	(54)	(51)
Other income, net	55	56
(LOSS)/INCOME FROM OPERATIONS BEFORE INCOME TAXES	360	264
Benefit from/(provision for) income taxes	(67)	(43)
Equity account for subsidiaries	0	0
NET INCOME	293	221
Income attributable to non-controlling interests	(6)	(6)
NET INCOME ATTRIBUTABLE TO WILLIS TOWERS WATSON	287	215
Comprehensive income before non-controlling interests	315	305
Comprehensive income attributable to non-controlling interests	(5)	(7)
Comprehensive income attributable to Willis Towers Watson	310	298
Other guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue	0	0
Costs of providing services
Salaries and benefits	0	0
Other operating expenses	37	42
Depreciation	1	1
Amortization	1	1
Transaction and integration expenses	0	1
Total costs of providing services	39	45
Income from operations	(39)	(45)
Intercompany (expense)/income	66	92
Interest expense	0	0
Other income, net	0	1
(LOSS)/INCOME FROM OPERATIONS BEFORE INCOME TAXES	27	48
Benefit from/(provision for) income taxes	(4)	(8)
Equity account for subsidiaries	270	181
NET INCOME	293	221
Income attributable to non-controlling interests	0	0
NET INCOME ATTRIBUTABLE TO WILLIS TOWERS WATSON	293	221
Comprehensive income before non-controlling interests	317	303
Comprehensive income attributable to non-controlling interests	0	0
Comprehensive income attributable to Willis Towers Watson	317	303
Non-guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue	2,290	2,286
Costs of providing services
Salaries and benefits	1,332	1,361
Other operating expenses	373	376
Depreciation	53	48
Amortization	126	140
Transaction and integration expenses	6	37
Total costs of providing services	1,890	1,962
Income from operations	400	324
Intercompany (expense)/income	(77)	(117)
Interest expense	(4)	(6)
Other income, net	55	55
(LOSS)/INCOME FROM OPERATIONS BEFORE INCOME TAXES	374	256
Benefit from/(provision for) income taxes	(69)	(39)
Equity account for subsidiaries	0	0
NET INCOME	305	217
Income attributable to non-controlling interests	(6)	(6)
NET INCOME ATTRIBUTABLE TO WILLIS TOWERS WATSON	299	211
Comprehensive income before non-controlling interests	298	338
Comprehensive income attributable to non-controlling interests	(5)	(7)
Comprehensive income attributable to Willis Towers Watson	293	331
Reportable Legal Entities [Member] \| Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue	0	0
Costs of providing services
Salaries and benefits	1	1
Other operating expenses	1	0
Depreciation	0	0
Amortization	0	0
Transaction and integration expenses	0	0
Total costs of providing services	2	1
Income from operations	(2)	(1)
Intercompany (expense)/income	0	0
Interest expense	(7)	(7)
Other income, net	0	0
(LOSS)/INCOME FROM OPERATIONS BEFORE INCOME TAXES	(9)	(8)
Benefit from/(provision for) income taxes	0	0
Equity account for subsidiaries	296	223
NET INCOME	287	215
Income attributable to non-controlling interests	0	0
NET INCOME ATTRIBUTABLE TO WILLIS TOWERS WATSON	287	215
Comprehensive income before non-controlling interests	311	298
Comprehensive income attributable to non-controlling interests	0	0
Comprehensive income attributable to Willis Towers Watson	311	298
Consolidating adjustments [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue	0	0
Costs of providing services
Salaries and benefits	0	0
Other operating expenses	0	0
Depreciation	0	0
Amortization	0	0
Transaction and integration expenses	0	0
Total costs of providing services	0	0
Income from operations	0	0
Intercompany (expense)/income	0	0
Interest expense	0	0
Other income, net	0	0
(LOSS)/INCOME FROM OPERATIONS BEFORE INCOME TAXES	0	0
Benefit from/(provision for) income taxes	0	0
Equity account for subsidiaries	(854)	(539)
NET INCOME	(854)	(539)
Income attributable to non-controlling interests	0	0
NET INCOME ATTRIBUTABLE TO WILLIS TOWERS WATSON	(854)	(539)
Comprehensive income before non-controlling interests	(834)	(838)
Comprehensive income attributable to non-controlling interests	0	0
Comprehensive income attributable to Willis Towers Watson	(834)	(838)
Willis North America [Member] \| Reportable Legal Entities [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue	22	6
Costs of providing services
Salaries and benefits	15	15
Other operating expenses	7	5
Depreciation	0	0
Amortization	0	0
Transaction and integration expenses	0	5
Total costs of providing services	22	25
Income from operations	0	(19)
Intercompany (expense)/income	(12)	(5)
Interest expense	(21)	(11)
Other income, net	0	0
(LOSS)/INCOME FROM OPERATIONS BEFORE INCOME TAXES	(33)	(35)
Benefit from/(provision for) income taxes	7	5
Equity account for subsidiaries	67	(7)
NET INCOME	41	(37)
Income attributable to non-controlling interests	0	0
NET INCOME ATTRIBUTABLE TO WILLIS TOWERS WATSON	41	(37)
Comprehensive income before non-controlling interests	19	(22)
Comprehensive income attributable to non-controlling interests	0	0
Comprehensive income attributable to Willis Towers Watson	19	(22)
Trinity Acquisition plc [Member] \| Reportable Legal Entities [Member]
Condensed Financial Statements, Captions [Line Items]
Revenue	0	0
Costs of providing services
Salaries and benefits	0	0
Other operating expenses	0	0
Depreciation	0	0
Amortization	0	0
Transaction and integration expenses	0	0
Total costs of providing services	0	0
Income from operations	0	0
Intercompany (expense)/income	23	30
Interest expense	(22)	(27)
Other income, net	0	0
(LOSS)/INCOME FROM OPERATIONS BEFORE INCOME TAXES	1	3
Benefit from/(provision for) income taxes	(1)	(1)
Equity account for subsidiaries	221	142
NET INCOME	221	144
Income attributable to non-controlling interests	0	0
NET INCOME ATTRIBUTABLE TO WILLIS TOWERS WATSON	221	144
Comprehensive income before non-controlling interests	204	226
Comprehensive income attributable to non-controlling interests	0	0
Comprehensive income attributable to Willis Towers Watson	$ 204	$ 226

Financial Information for Issuers and Other Guarantor Subsidiaries - Unaudited Condensed Consolidated Balance Sheet (Details) - USD ($) $ in Millions	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
ASSETS
Cash and cash equivalents	$ 992		$ 1,033	$ 954	$ 1,030
Fiduciary assets	15,129		12,604
Accounts receivable, net	2,490		2,379
Prepaid and other current assets	409		404
Total current assets	19,020		16,420
Intercompany receivables, net	0		0
Fixed assets, net	957		942
Goodwill	10,456		10,465
Other intangible assets, net	3,187		3,318
Right-of-use assets	946	$ 1,000
Pension benefits assets	833		773
Other non-current assets	494		467
Total non-current assets	16,873		15,965
Investments in subsidiaries	0		0
TOTAL ASSETS	35,893		32,385
LIABILITIES AND EQUITY
Fiduciary liabilities	15,129		12,604
Deferred revenue and accrued expenses	1,240		1,647
Current debt	187		186
Current lease liabilities	158
Other current liabilities	940		864
Total current liabilities	17,654		15,301
Intercompany payables, net	0		0
Long-term debt	4,518		4,389
Liability for pension benefits	1,135		1,170
Deferred tax liabilities	544		559
Provision for liabilities	543		540
Long-term lease liabilities	961
Other non-current liabilities	296		429
Total non-current liabilities	7,997		7,087
TOTAL LIABILITIES	25,651		22,388
REDEEMABLE NON-CONTROLLING INTEREST	28		26
EQUITY
Total Willis Towers Watson shareholders’ equity	10,092		9,852
Non-controlling interests	122		119
Total equity	10,214		9,971	10,802	10,249
TOTAL LIABILITIES AND EQUITY	35,893		32,385
Other guarantors [Member]
ASSETS
Cash and cash equivalents	0		0	1	1
Fiduciary assets	0		0
Accounts receivable, net	0		0
Prepaid and other current assets	30		33
Total current assets	30		33
Intercompany receivables, net	0		0
Fixed assets, net	17		16
Goodwill	0		0
Other intangible assets, net	57		58
Right-of-use assets	0
Pension benefits assets	0		0
Other non-current assets	48		49
Total non-current assets	122		123
Investments in subsidiaries	7,947		8,108
TOTAL ASSETS	8,099		8,264
LIABILITIES AND EQUITY
Fiduciary liabilities	0		0
Deferred revenue and accrued expenses	3		3
Current debt	0		0
Current lease liabilities	0
Other current liabilities	5		13
Total current liabilities	8		16
Intercompany payables, net	4,709		4,691
Long-term debt	0		0
Liability for pension benefits	0		0
Deferred tax liabilities	0		0
Provision for liabilities	0		0
Long-term lease liabilities	0
Other non-current liabilities	2		5
Total non-current liabilities	4,711		4,696
TOTAL LIABILITIES	4,719		4,712
REDEEMABLE NON-CONTROLLING INTEREST	0		0
EQUITY
Total Willis Towers Watson shareholders’ equity	3,380		3,552
Non-controlling interests	0		0
Total equity	3,380		3,552
TOTAL LIABILITIES AND EQUITY	8,099		8,264
Non-guarantors [Member]
ASSETS
Cash and cash equivalents	992		1,033	953	1,027
Fiduciary assets	15,129		12,604
Accounts receivable, net	2,462		2,355
Prepaid and other current assets	338		357
Total current assets	18,921		16,349
Intercompany receivables, net	0		0
Fixed assets, net	940		926
Goodwill	10,456		10,465
Other intangible assets, net	3,187		3,318
Right-of-use assets	946
Pension benefits assets	833		773
Other non-current assets	420		452
Total non-current assets	16,782		15,934
Investments in subsidiaries	0		0
TOTAL ASSETS	35,703		32,283
LIABILITIES AND EQUITY
Fiduciary liabilities	15,129		12,604
Deferred revenue and accrued expenses	1,237		1,641
Current debt	0		0
Current lease liabilities	158
Other current liabilities	1,070		935
Total current liabilities	17,594		15,180
Intercompany payables, net	728		517
Long-term debt	1		0
Liability for pension benefits	1,135		1,170
Deferred tax liabilities	662		688
Provision for liabilities	423		420
Long-term lease liabilities	961
Other non-current liabilities	278		411
Total non-current liabilities	4,188		3,206
TOTAL LIABILITIES	21,782		18,386
REDEEMABLE NON-CONTROLLING INTEREST	28		26
EQUITY
Total Willis Towers Watson shareholders’ equity	13,771		13,752
Non-controlling interests	122		119
Total equity	13,893		13,871
TOTAL LIABILITIES AND EQUITY	35,703		32,283
Reportable Legal Entities [Member] \| Parent Company [Member]
ASSETS
Cash and cash equivalents	0		0	0	2
Fiduciary assets	0		0
Accounts receivable, net	0		0
Prepaid and other current assets	0		0
Total current assets	0		0
Intercompany receivables, net	4,733		4,755
Fixed assets, net	0		0
Goodwill	0		0
Other intangible assets, net	0		0
Right-of-use assets	0
Pension benefits assets	0		0
Other non-current assets	0		0
Total non-current assets	4,733		4,755
Investments in subsidiaries	5,952		5,691
TOTAL ASSETS	10,685		10,446
LIABILITIES AND EQUITY
Fiduciary liabilities	0		0
Deferred revenue and accrued expenses	0		1
Current debt	0		0
Current lease liabilities	0
Other current liabilities	97		95
Total current liabilities	97		96
Intercompany payables, net	0		0
Long-term debt	498		498
Liability for pension benefits	0		0
Deferred tax liabilities	0		0
Provision for liabilities	0		0
Long-term lease liabilities	0
Other non-current liabilities	0		0
Total non-current liabilities	498		498
TOTAL LIABILITIES	595		594
REDEEMABLE NON-CONTROLLING INTEREST	0		0
EQUITY
Total Willis Towers Watson shareholders’ equity	10,090		9,852
Non-controlling interests	0		0
Total equity	10,090		9,852
TOTAL LIABILITIES AND EQUITY	10,685		10,446
Consolidating adjustments [Member]
ASSETS
Cash and cash equivalents	0		0	0	0
Fiduciary assets	0		0
Accounts receivable, net	0		0
Prepaid and other current assets	(331)		(298)
Total current assets	(331)		(298)
Intercompany receivables, net	(6,185)		(6,110)
Fixed assets, net	0		0
Goodwill	0		0
Other intangible assets, net	(57)		(58)
Right-of-use assets	0
Pension benefits assets	0		0
Other non-current assets	(118)		(128)
Total non-current assets	(6,360)		(6,296)
Investments in subsidiaries	(22,826)		(23,125)
TOTAL ASSETS	(29,517)		(29,719)
LIABILITIES AND EQUITY
Fiduciary liabilities	0		0
Deferred revenue and accrued expenses	0		0
Current debt	0		0
Current lease liabilities	0
Other current liabilities	(279)		(250)
Total current liabilities	(279)		(250)
Intercompany payables, net	(6,185)		(6,110)
Long-term debt	0		0
Liability for pension benefits	0		0
Deferred tax liabilities	(118)		(129)
Provision for liabilities	0		0
Long-term lease liabilities	0
Other non-current liabilities	0		0
Total non-current liabilities	(6,303)		(6,239)
TOTAL LIABILITIES	(6,582)		(6,489)
REDEEMABLE NON-CONTROLLING INTEREST	0		0
EQUITY
Total Willis Towers Watson shareholders’ equity	(22,935)		(23,230)
Non-controlling interests	0		0
Total equity	(22,935)		(23,230)
TOTAL LIABILITIES AND EQUITY	(29,517)		(29,719)
Willis North America [Member] \| Reportable Legal Entities [Member]
ASSETS
Cash and cash equivalents	0		0	0	0
Fiduciary assets	0		0
Accounts receivable, net	28		24
Prepaid and other current assets	371		311
Total current assets	399		335
Intercompany receivables, net	0		0
Fixed assets, net	0		0
Goodwill	0		0
Other intangible assets, net	0		0
Right-of-use assets	0
Pension benefits assets	0		0
Other non-current assets	142		92
Total non-current assets	142		92
Investments in subsidiaries	6,401		6,649
TOTAL ASSETS	6,942		7,076
LIABILITIES AND EQUITY
Fiduciary liabilities	0		0
Deferred revenue and accrued expenses	0		2
Current debt	187		186
Current lease liabilities	0
Other current liabilities	28		38
Total current liabilities	215		226
Intercompany payables, net	748		902
Long-term debt	1,655		1,635
Liability for pension benefits	0		0
Deferred tax liabilities	0		0
Provision for liabilities	120		120
Long-term lease liabilities	0
Other non-current liabilities	16		13
Total non-current liabilities	2,539		2,670
TOTAL LIABILITIES	2,754		2,896
REDEEMABLE NON-CONTROLLING INTEREST	0		0
EQUITY
Total Willis Towers Watson shareholders’ equity	4,188		4,180
Non-controlling interests	0		0
Total equity	4,188		4,180
TOTAL LIABILITIES AND EQUITY	6,942		7,076
Trinity Acquisition plc [Member] \| Reportable Legal Entities [Member]
ASSETS
Cash and cash equivalents	0		0	$ 0	$ 0
Fiduciary assets	0		0
Accounts receivable, net	0		0
Prepaid and other current assets	1		1
Total current assets	1		1
Intercompany receivables, net	1,452		1,355
Fixed assets, net	0		0
Goodwill	0		0
Other intangible assets, net	0		0
Right-of-use assets	0
Pension benefits assets	0		0
Other non-current assets	2		2
Total non-current assets	1,454		1,357
Investments in subsidiaries	2,526		2,677
TOTAL ASSETS	3,981		4,035
LIABILITIES AND EQUITY
Fiduciary liabilities	0		0
Deferred revenue and accrued expenses	0		0
Current debt	0		0
Current lease liabilities	0
Other current liabilities	19		33
Total current liabilities	19		33
Intercompany payables, net	0		0
Long-term debt	2,364		2,256
Liability for pension benefits	0		0
Deferred tax liabilities	0		0
Provision for liabilities	0		0
Long-term lease liabilities	0
Other non-current liabilities	0		0
Total non-current liabilities	2,364		2,256
TOTAL LIABILITIES	2,383		2,289
REDEEMABLE NON-CONTROLLING INTEREST	0		0
EQUITY
Total Willis Towers Watson shareholders’ equity	1,598		1,746
Non-controlling interests	0		0
Total equity	1,598		1,746
TOTAL LIABILITIES AND EQUITY	$ 3,981		$ 4,035

Financial Information for Issuers and Other Guarantor Subsidiaries - Unaudited Condensed Consolidated Statement of Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Condensed Financial Statements, Captions [Line Items]
NET CASH FROM/(USED IN) OPERATING ACTIVITIES	$ (47)	$ 18
Additions to fixed assets and software for internal use	(57)	(65)
Capitalized software costs	(17)	(13)
Acquisitions of operations, net of cash acquired	(1)	(5)
Net proceeds from sale of operations	0	4
(Repayments of)/proceeds from intercompany investing activities, net	0	0
Net cash used in investing activities	(75)	(79)
Additions to fixed assets and software for internal use	(57)	(65)
Capitalized software costs	(17)	(13)
Acquisitions of operations, net of cash acquired	(1)	(5)
Net proceeds from sale of operations	0	4
Proceeds from/(repayments of) intercompany investing activities, net	0	0
Net cash used in investing activities	(75)	(79)
CASH FLOWS (USED IN)/FROM FINANCING ACTIVITIES
Net borrowings on revolving credit facility	138	61
Repayments of debt	(1)	(21)
Proceeds from issuance of shares	22	11
Cash paid for employee taxes on withholding shares	0	(7)
Dividends paid	(77)	(68)
(Repayments of)/proceeds from intercompany financing activities, net	0	0
Net cash from/(used in) financing activities	82	(24)
DECREASE IN CASH AND CASH EQUIVALENTS	(40)	(85)
Effect of exchange rate changes on cash and cash equivalents	(1)	9
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	1,033	1,030
CASH AND CASH EQUIVALENTS, END OF PERIOD	992	954
Other guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
NET CASH FROM/(USED IN) OPERATING ACTIVITIES	(82)	245
Additions to fixed assets and software for internal use	(1)	(1)
Capitalized software costs	0	0
Acquisitions of operations, net of cash acquired	0	0
Net proceeds from sale of operations		0
(Repayments of)/proceeds from intercompany investing activities, net	78	63
Net cash used in investing activities	77	62
Additions to fixed assets and software for internal use	(1)	(1)
Capitalized software costs	0	0
Acquisitions of operations, net of cash acquired	0	0
Net proceeds from sale of operations		0
Proceeds from/(repayments of) intercompany investing activities, net	(78)	(63)
Net cash used in investing activities	77	62
CASH FLOWS (USED IN)/FROM FINANCING ACTIVITIES
Net borrowings on revolving credit facility	0	0
Repayments of debt	0	0
Proceeds from issuance of shares	0	0
Cash paid for employee taxes on withholding shares	0	0
Dividends paid	0	(1)
(Repayments of)/proceeds from intercompany financing activities, net	5	(306)
Net cash from/(used in) financing activities	5	(307)
DECREASE IN CASH AND CASH EQUIVALENTS	0	0
Effect of exchange rate changes on cash and cash equivalents	0	0
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	0	1
CASH AND CASH EQUIVALENTS, END OF PERIOD	0	1
Non-guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
NET CASH FROM/(USED IN) OPERATING ACTIVITIES	158	328
Additions to fixed assets and software for internal use	(56)	(64)
Capitalized software costs	(17)	(13)
Acquisitions of operations, net of cash acquired	(1)	(5)
Net proceeds from sale of operations		4
(Repayments of)/proceeds from intercompany investing activities, net	(34)	(195)
Net cash used in investing activities	(108)	(273)
Additions to fixed assets and software for internal use	(56)	(64)
Capitalized software costs	(17)	(13)
Acquisitions of operations, net of cash acquired	(1)	(5)
Net proceeds from sale of operations		4
Proceeds from/(repayments of) intercompany investing activities, net	34	195
Net cash used in investing activities	(108)	(273)
CASH FLOWS (USED IN)/FROM FINANCING ACTIVITIES
Net borrowings on revolving credit facility	0	0
Repayments of debt	(1)	(21)
Proceeds from issuance of shares	0	0
Cash paid for employee taxes on withholding shares	0	(7)
Dividends paid	0	0
(Repayments of)/proceeds from intercompany financing activities, net	(89)	(110)
Net cash from/(used in) financing activities	(90)	(138)
DECREASE IN CASH AND CASH EQUIVALENTS	(40)	(83)
Effect of exchange rate changes on cash and cash equivalents	(1)	9
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	1,033	1,027
CASH AND CASH EQUIVALENTS, END OF PERIOD	992	953
Reportable Legal Entities [Member] \| Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
NET CASH FROM/(USED IN) OPERATING ACTIVITIES	38	72
Additions to fixed assets and software for internal use	0	0
Capitalized software costs	0	0
Acquisitions of operations, net of cash acquired	0	0
Net proceeds from sale of operations		0
(Repayments of)/proceeds from intercompany investing activities, net	17	(17)
Net cash used in investing activities	17	(17)
Additions to fixed assets and software for internal use	0	0
Capitalized software costs	0	0
Acquisitions of operations, net of cash acquired	0	0
Net proceeds from sale of operations		0
Proceeds from/(repayments of) intercompany investing activities, net	(17)	17
Net cash used in investing activities	17	(17)
CASH FLOWS (USED IN)/FROM FINANCING ACTIVITIES
Net borrowings on revolving credit facility	0	0
Repayments of debt	0	0
Proceeds from issuance of shares	22	11
Cash paid for employee taxes on withholding shares	0	0
Dividends paid	(77)	(68)
(Repayments of)/proceeds from intercompany financing activities, net	0	0
Net cash from/(used in) financing activities	(55)	(57)
DECREASE IN CASH AND CASH EQUIVALENTS	0	(2)
Effect of exchange rate changes on cash and cash equivalents	0	0
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	0	2
CASH AND CASH EQUIVALENTS, END OF PERIOD	0	0
Consolidating adjustments [Member]
Condensed Financial Statements, Captions [Line Items]
NET CASH FROM/(USED IN) OPERATING ACTIVITIES	0	(333)
Additions to fixed assets and software for internal use	0	0
Capitalized software costs	0	0
Acquisitions of operations, net of cash acquired	0	0
Net proceeds from sale of operations		0
(Repayments of)/proceeds from intercompany investing activities, net	(35)	(244)
Net cash used in investing activities	(35)	(244)
Additions to fixed assets and software for internal use	0	0
Capitalized software costs	0	0
Acquisitions of operations, net of cash acquired	0	0
Net proceeds from sale of operations		0
Proceeds from/(repayments of) intercompany investing activities, net	35	244
Net cash used in investing activities	(35)	(244)
CASH FLOWS (USED IN)/FROM FINANCING ACTIVITIES
Net borrowings on revolving credit facility	0	0
Repayments of debt	0	0
Proceeds from issuance of shares	0	0
Cash paid for employee taxes on withholding shares	0	0
Dividends paid	0	333
(Repayments of)/proceeds from intercompany financing activities, net	35	244
Net cash from/(used in) financing activities	35	577
DECREASE IN CASH AND CASH EQUIVALENTS	0	0
Effect of exchange rate changes on cash and cash equivalents	0	0
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	0	0
CASH AND CASH EQUIVALENTS, END OF PERIOD	0	0
Willis North America [Member] \| Reportable Legal Entities [Member]
Condensed Financial Statements, Captions [Line Items]
NET CASH FROM/(USED IN) OPERATING ACTIVITIES	(130)	(98)
Additions to fixed assets and software for internal use	0	0
Capitalized software costs	0	0
Acquisitions of operations, net of cash acquired	0	0
Net proceeds from sale of operations		0
(Repayments of)/proceeds from intercompany investing activities, net	111	67
Net cash used in investing activities	111	67
Additions to fixed assets and software for internal use	0	0
Capitalized software costs	0	0
Acquisitions of operations, net of cash acquired	0	0
Net proceeds from sale of operations		0
Proceeds from/(repayments of) intercompany investing activities, net	(111)	(67)
Net cash used in investing activities	111	67
CASH FLOWS (USED IN)/FROM FINANCING ACTIVITIES
Net borrowings on revolving credit facility	20	55
Repayments of debt	0	0
Proceeds from issuance of shares	0	0
Cash paid for employee taxes on withholding shares	0	0
Dividends paid	0	0
(Repayments of)/proceeds from intercompany financing activities, net	(1)	(24)
Net cash from/(used in) financing activities	19	31
DECREASE IN CASH AND CASH EQUIVALENTS	0	0
Effect of exchange rate changes on cash and cash equivalents	0	0
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	0	0
CASH AND CASH EQUIVALENTS, END OF PERIOD	0	0
Trinity Acquisition plc [Member] \| Reportable Legal Entities [Member]
Condensed Financial Statements, Captions [Line Items]
NET CASH FROM/(USED IN) OPERATING ACTIVITIES	(31)	(196)
Additions to fixed assets and software for internal use	0	0
Capitalized software costs	0	0
Acquisitions of operations, net of cash acquired	0	0
Net proceeds from sale of operations		0
(Repayments of)/proceeds from intercompany investing activities, net	(137)	326
Net cash used in investing activities	(137)	326
Additions to fixed assets and software for internal use	0	0
Capitalized software costs	0	0
Acquisitions of operations, net of cash acquired	0	0
Net proceeds from sale of operations		0
Proceeds from/(repayments of) intercompany investing activities, net	137	(326)
Net cash used in investing activities	(137)	326
CASH FLOWS (USED IN)/FROM FINANCING ACTIVITIES
Net borrowings on revolving credit facility	118	6
Repayments of debt	0	0
Proceeds from issuance of shares	0	0
Cash paid for employee taxes on withholding shares	0	0
Dividends paid	0	(332)
(Repayments of)/proceeds from intercompany financing activities, net	50	196
Net cash from/(used in) financing activities	168	(130)
DECREASE IN CASH AND CASH EQUIVALENTS	0	0
Effect of exchange rate changes on cash and cash equivalents	0	0
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	0	0
CASH AND CASH EQUIVALENTS, END OF PERIOD	$ 0	$ 0

Condensed Consolidated Statements of Changes in Equity (Unaudited) (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement Of Stockholders Equity [Abstract]
Dividends declared per share	$ 0.65	$ 0.60

Nature of Operations (Details)	Mar. 31, 2019 employee Country
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Number of employees employed (more than 43,000) \| employee	43,000
Number of countries in which entity operates (more than 140) \| Country	140

Revenue - Schedule of Disaggregation of Revenue (Parenthetical) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Outsourced administration [Member] \| HCB [Member]
Disaggregation Of Revenue [Line Items]
Revenue prior period reclassification adjustment	$ 58

Revenue - Schedule of Contract Balances (Parenthetical) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Mar. 31, 2018
Revenue From Contract With Customer [Abstract]
Allowance for doubtful debts	$ 44	$ 40

Fair Value Measurements - Narrative (Details) - USD ($)	3 Months Ended
Fair Value Measurements - Narrative (Details) - USD ($)	Mar. 31, 2019	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair value significant transfers between Levels 1, 2 or 3	$ 0	$ 0