10-Q

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

_____________________________________________ 

FORM 10-Q

_____________________________________________ 

Quarterly Report Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

For the quarterly period ended June 30, 2017

_____________________________________________ 

Marsh & McLennan Companies, Inc.

1166 Avenue of the Americas

New York, New York 10036

(212) 345-5000

_____________________________________________ 

Commission file number 1-5998

State of Incorporation: Delaware

I.R.S. Employer Identification No. 36-2668272

_____________________________________________ 

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    Yes  ý    No  ¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Website, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    Yes  ý    No  ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company. See the definitions of "large accelerated filer," "accelerated filer," "smaller reporting company," and "emerging growth company" in Rule 12b-2 of the Exchange Act.

Large Accelerated Filer  x	Accelerated Filer  ¨
Non-Accelerated Filer  ¨(Do not check if a smaller reporting company)	Smaller Reporting Company  ¨
	Emerging Growth Company ¨

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. o

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).     Yes  ¨    No  ý

As of July 25, 2017, there were outstanding 512,524,877 shares of common stock, par value $1.00 per share, of the registrant.

INFORMATION CONCERNING FORWARD-LOOKING STATEMENTS

This Quarterly Report on Form 10-Q contains "forward-looking statements," as defined in the Private Securities Litigation Reform Act of 1995. These statements, which express management's current views concerning future events or results, use words like "anticipate," "assume," "believe," "continue," "estimate," "expect," "intend," "plan," "project" and similar terms, and future or conditional tense verbs like "could," "may," "might," "should," "will" and "would." Forward-looking statements are subject to inherent risks and uncertainties that could cause actual results to differ materially from those expressed or implied in our forward-looking statements.

Factors that could materially affect our future results include, among other things: the impact of any investigations, reviews or other activity by regulatory or law enforcement authorities in the U.S., U.K. and other countries, including the U.K. Financial Conduct Authority's ongoing investigation into the aviation insurance and reinsurance sector; the impact from lawsuits, other contingent liabilities and loss contingencies arising from errors and omissions, breach of fiduciary duty and other claims against us; our ability to compete effectively and adapt to changes in the competitive environment, including to respond to disintermediation, pricing pressures and technological and other types of innovation; our exposure to potential civil damages, criminal penalties or other consequences, such as reputational impact, if we fail to comply with applicable U.S. and non-U.S. laws and regulations; our organization's ability to maintain adequate safeguards to protect the security of our information systems and confidential, personal or proprietary information, particularly given the volume of third party vendors we use; our ability to successfully recover if we experience a business continuity problem due to cyberattack, natural disaster or otherwise; the impact of macroeconomic conditions, political events and market conditions on us, our clients and the industries in which we operate; the financial and operational impact of complying with laws and regulations where we operate, including the E.U.’s General Data Protection Regulation; our ability to attract and retain key employees; the effect of our global pension obligations on our financial position, earnings and cash flows and the impact of low interest rates on those obligations; the impact on our competitive position of our tax rate relative to our competitors; the impact of fluctuations in foreign exchange, interest rates and securities markets on our results; and the impact of changes in accounting rules or in our accounting estimates or assumptions.

The factors identified above are not exhaustive. We caution readers not to place undue reliance on any forward-looking statements, which are based only on information currently available to us and speak only as of the dates on which they are made. The Company undertakes no obligation to update or revise any forward-looking statement to reflect events or circumstances arising after the date on which it is made.

Further information concerning Marsh & McLennan Companies and its businesses, including information about factors that could materially affect our results of operations and financial condition, is contained in the Company's filings with the Securities and Exchange Commission, including the "Risk Factors" section and in the "Management’s Discussion and Analysis of Financial Condition and Results of Operations" section of our most recently filed Annual Report on Form 10-K.

2

TABLE OF CONTENTS

PART I. FINANCIAL INFORMATION		4
ITEM 1.	FINANCIAL STATEMENTS (UNAUDITED)	4
	CONSOLIDATED STATEMENTS OF INCOME	4
	CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME	5
	CONSOLIDATED BALANCE SHEETS	6
	CONSOLIDATED BALANCE SHEETS (Continued)	7
	CONSOLIDATED STATEMENTS OF CASH FLOWS	8
	CONSOLIDATED STATEMENTS OF EQUITY	9
	NOTES TO CONSOLIDATED FINANCIAL STATEMENTS	10
ITEM 2.	MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS	32
	OF OPERATIONS
ITEM 3.	QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK	43
ITEM 4.	CONTROLS & PROCEDURES	45
PART II. OTHER INFORMATION		46
ITEM 1.	LEGAL PROCEEDINGS	46
ITEM 1A.	RISK FACTORS	46
ITEM 2.	UNREGISTERED SALES OF EQUITY SECURITIES AND USE OF PROCEEDS	46
ITEM 3.	DEFAULTS UPON SENIOR SECURITIES	47
ITEM 4.	MINE SAFETY DISCLOSURE	47
ITEM 5.	OTHER INFORMATION	47
ITEM 6.	EXHIBITS	47

3

PART I.    FINANCIAL INFORMATION

Item 1. Financial Statements.

MARSH & McLENNAN COMPANIES, INC. AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF INCOME

(Unaudited)

	Three Months Ended June 30,						Six Months Ended June 30,
(In millions, except per share amounts)	2017			2016			2017			2016
Revenue	$	3,495		$	3,376		$	6,998		$	6,712
Expense:
Compensation and benefits	1,935			1,872			3,880			3,726
Other operating expenses	796			778			1,545			1,527
Operating expenses	2,731			2,650			5,425			5,253
Operating income	764			726			1,573			1,459
Interest income	2			2			4			4
Interest expense	(60		)	(48		)	(118		)	(94		)
Investment income (loss)	5			1			5			(2		)
Income before income taxes	711			681			1,464			1,367
Income tax expense	204			201			379			397
Net income before non-controlling interests	507			480			1,085			970
Less: Net income attributable to non-controlling interests	6			8			15			17
Net income attributable to the Company	$	501		$	472		$	1,070		$	953
Net Income Per Share Attributable to the Company:
Basic	$	0.98		$	0.91		$	2.08		$	1.83
Diluted	$	0.96		$	0.90		$	2.05		$	1.81
Average number of shares outstanding:
Basic	514			521			514			521
Diluted	520			525			521			526
Shares outstanding at June 30,	513			519			513			519

The accompanying notes are an integral part of these unaudited consolidated statements.

4

MARSH & McLENNAN COMPANIES, INC. AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

(Unaudited)

	Three Months Ended June 30,						Six Months Ended June 30,
(In millions)	2017			2016			2017		2016
Net income before non-controlling interests	$	507		$	480		$	1,085	$	970
Other comprehensive income (loss), before tax:
Foreign currency translation adjustments	290			(334		)	525		(321		)
Unrealized investment gains	24			—			19		—
(Loss) gain related to pension/post-retirement plans	(5		)	163			28		301
Other comprehensive income (loss), before tax	309			(171		)	572		(20		)
Income tax expense on other comprehensive income	13			33			20		61
Other comprehensive income (loss), net of tax	296			(204		)	552		(81		)
Comprehensive income	803			276			1,637		889
Less: comprehensive income attributable to non-controlling interest	6			8			15		17
Comprehensive income attributable to the Company	$	797		$	268		$	1,622	$	872

The accompanying notes are an integral part of these unaudited consolidated statements.

5

MARSH & McLENNAN COMPANIES, INC. AND SUBSIDIARIES

CONSOLIDATED BALANCE SHEETS

(In millions, except share amounts)	(Unaudited) June 30, 2017			December 31, 2016
ASSETS
Current assets:
Cash and cash equivalents	$	966		$	1,026
Receivables
Commissions and fees	3,740			3,370
Advanced premiums and claims	49			83
Other	298			286
	4,087			3,739
Less-allowance for doubtful accounts and cancellations	(103		)	(96		)
Net receivables	3,984			3,643
Other current assets	232			215
Total current assets	5,182			4,884
Goodwill	8,821			8,369
Other intangible assets	1,233			1,126
Fixed assets (net of accumulated depreciation and amortization of $1,758 at June 30, 2017 and $1,683 at December 31, 2016)	721			725
Pension related assets	981			776
Deferred tax assets	975			1,097
Other assets	1,529			1,213
	$	19,442		$	18,190

The accompanying notes are an integral part of these consolidated statements.

6

MARSH & McLENNAN COMPANIES, INC. AND SUBSIDIARIES

CONSOLIDATED BALANCE SHEETS (Continued)

(In millions, except share amounts)	(Unaudited) June 30, 2017			December 31, 2016
LIABILITIES AND EQUITY
Current liabilities:
Short-term debt	$	162		$	312
Accounts payable and accrued liabilities	2,027			1,969
Accrued compensation and employee benefits	1,073			1,655
Accrued income taxes	193			146
Dividends payable	194			—
Total current liabilities	3,649			4,082
Fiduciary liabilities	5,039			4,241
Less – cash and investments held in a fiduciary capacity	(5,039		)	(4,241		)
	—			—
Long-term debt	5,479			4,495
Pension, post-retirement and post-employment benefits	1,986			2,076
Liabilities for errors and omissions	305			308
Other liabilities	949			957
Commitments and contingencies	—			—
Equity:
Preferred stock, $1 par value, authorized 6,000,000 shares, none issued	—			—
Common stock, $1 par value, authorized
1,600,000,000 shares, issued 560,641,640 shares at June 30, 2017
and December 31, 2016	561			561
Additional paid-in capital	763			842
Retained earnings	12,915			12,388
Accumulated other comprehensive loss	(4,541		)	(5,093		)
Non-controlling interests	81			80
	9,779			8,778
Less – treasury shares, at cost, 47,837,649 shares at June 30, 2017
and 46,150,415 shares at December 31, 2016	(2,705		)	(2,506		)
Total equity	7,074			6,272
	$	19,442		$	18,190

The accompanying notes are an integral part of these consolidated statements.

7

MARSH & McLENNAN COMPANIES, INC. AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF CASH FLOWS

(Unaudited)

For the Six Months Ended June 30,
(In millions)	2017			2016
Operating cash flows:
Net income before non-controlling interests	$	1,085		$	970
Adjustments to reconcile net income to cash provided by operations:
Depreciation and amortization of fixed assets and capitalized software	156			154
Amortization of intangible assets	80			67
Adjustments and payments related to contingent consideration liability	(13		)	(8		)
Gain on deconsolidation of subsidiary	—			(12		)
Provision for deferred income taxes	42			48
(Gain) loss on investments	(5		)	2
Loss on disposition of assets	9			3
Share-based compensation expense	75			58
Changes in assets and liabilities:
Net receivables	(318		)	(280		)
Other current assets	(18		)	(37		)
Other assets	(34		)	(1		)
Accounts payable and accrued liabilities	52			(24		)
Accrued compensation and employee benefits	(579		)	(645		)
Accrued income taxes	45			35
Contributions to pension and other benefit plans in excess of current year expense/credit	(214		)	(139		)
Other liabilities	9			(10		)
Effect of exchange rate changes	(29		)	48
Net cash provided by operations	343			229
Financing cash flows:
Purchase of treasury shares	(400		)	(410		)
Net increase in commercial paper	100			—
Proceeds from debt	987			347
Repayments of debt	(256		)	(6		)
Shares withheld for taxes on vested units – treasury shares	(48		)	(38		)
Issuance of common stock from treasury shares	94			131
Payments of deferred and contingent consideration for acquisitions	(97		)	(63		)
Distributions of non-controlling interests	(13		)	(11		)
Dividends paid	(351		)	(326		)
Net cash provided by (used for) financing activities	16			(376		)
Investing cash flows:
Capital expenditures	(144		)	(114		)
Net sales (purchases) of long-term investments	12			(4		)
Proceeds from sales of fixed assets	4			1
Acquisitions	(412		)	(77		)
Other, net	2			4
Net cash used for investing activities	(538		)	(190		)
Effect of exchange rate changes on cash and cash equivalents	119			(63		)
Decrease in cash and cash equivalents	(60		)	(400		)
Cash and cash equivalents at beginning of period	1,026			1,374
Cash and cash equivalents at end of period	$	966		$	974

The accompanying notes are an integral part of these unaudited consolidated statements.

8

MARSH & McLENNAN COMPANIES, INC. AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF EQUITY

(Unaudited)

For the Six Months Ended June 30,
(In millions, except per share amounts)	2017			2016
COMMON STOCK
Balance, beginning and end of period	$	561		$	561
ADDITIONAL PAID-IN CAPITAL
Balance, beginning of year	$	842		$	861
Change in accrued stock compensation costs	(10		)	(10		)
Issuance of shares under stock compensation plans and employee stock purchase plans and related tax impact in 2016	(69		)	(62		)
Balance, end of period	$	763		$	789
RETAINED EARNINGS
Balance, beginning of year	$	12,388		$	11,302
Net income attributable to the Company	1,070			953
Dividend equivalents declared – (per share amounts: $1.06 in 2017 and $0.96 in 2016)	(2		)	(4		)
Dividends declared – (per share amounts: $1.06 in 2017 and $0.96 in 2016)	(541		)	(500		)
Balance, end of period	$	12,915		$	11,751
ACCUMULATED OTHER COMPREHENSIVE LOSS
Balance, beginning of year	$	(5,093	)	$	(4,220	)
Other comprehensive income (loss), net of tax	552			(81		)
Balance, end of period	$	(4,541	)	$	(4,301	)
TREASURY SHARES
Balance, beginning of year	$	(2,506	)	$	(1,991	)
Issuance of shares under stock compensation plans and employee stock purchase plans	201			225
Purchase of treasury shares	(400		)	(410		)
Balance, end of period	$	(2,705	)	$	(2,176	)
NON-CONTROLLING INTERESTS
Balance, beginning of year	$	80		$	89
Net income attributable to non-controlling interests	15			17
Deconsolidation of subsidiary	—			(14		)
Distributions and other changes	(14		)	(11		)
Balance, end of period	$	81		$	81
TOTAL EQUITY	$	7,074		$	6,705

The accompanying notes are an integral part of these unaudited consolidated statements.

9

MARSH & McLENNAN COMPANIES, INC. AND SUBSIDIARIES

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(Unaudited)

1.     Nature of Operations

Marsh & McLennan Companies, Inc. and its consolidated subsidiaries (the "Company"), a global professional services firm, is organized based on the different services that it offers. Under this structure, the Company’s two segments are Risk and Insurance Services and Consulting.

The Risk and Insurance Services segment provides risk management services and insurance broking, reinsurance broking and insurance program management services for businesses, public entities, insurance companies, associations, professional services organizations and private clients. The Company conducts business in this segment through Marsh and Guy Carpenter.

The Company conducts business in its Consulting segment through Mercer and Oliver Wyman Group. Mercer provides consulting expertise, advice, services and solutions in the areas of health, wealth and career. As of June 30, 2017, Mercer had assets under delegated management of $191 billion worldwide. Oliver Wyman Group provides specialized management and economic and brand consulting services.

Acquisitions impacting the Risk and Insurance Services and Consulting segments are discussed in Note 7 to the consolidated financial statements.

2.     Principles of Consolidation and Other Matters

The consolidated financial statements included herein have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission. While certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America have been omitted pursuant to such rules and regulations for interim filings, the Company believes that the information and disclosures presented are adequate to make such information and disclosures not misleading. These consolidated financial statements should be read in conjunction with the consolidated financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016 (the "2016 Form 10-K").

The financial information contained herein reflects all normal recurring adjustments which are, in the opinion of management, necessary for a fair presentation of the Company’s consolidated financial statements as of and for the three and six month periods ended June 30, 2017 and 2016.

Cash and Cash Equivalents

Cash and cash equivalents primarily consist of certificates of deposit and time deposits, with original maturities of three months or less, and money market funds. The estimated fair value of the Company's cash and cash equivalents approximates their carrying value. The Company is required to maintain operating funds of approximately$172 million, primarily related to regulatory requirements outside the United States or as collateral under captive insurance arrangements.

Investments

The Company holds investments in certain private equity funds. Investments in private equity funds are accounted for under the equity method of accounting using a consistently applied three-month lag period adjusted for any known significant changes from the lag period to the reporting date of the Company. The underlying private equity funds follow investment company accounting, where investments within the fund are carried at fair value. Investment gains or losses for the Company's proportionate share of the change in fair value of the funds are recorded in earnings. Investments accounted for using the equity method of accounting are included in other assets in the consolidated balance sheets.

The caption "Investment income (loss)" in the consolidated statements of income comprises realized and unrealized gains and losses from investments recognized in earnings. It includes, when applicable, other than temporary declines in the value of debt and available-for-sale securities and equity method gains or losses on the Company's investments in private equity funds. The Company recorded net investment income of $5 million in the second quarter of 2017 compared to $1 million for the same period in 2016, and net investment income of $5 million compared to a net investment loss of $2 million for the six months ended June 30, 2017 and 2016, respectively.

10

Income Taxes

The Company's effective tax rate in the second quarter of 2017 was 28.6% compared with 29.5% in the second quarter of 2016. The effective tax rate for the first six months of 2017 and 2016 was 25.9% and 29.0%, respectively. The rates reflect foreign operations which are taxed at rates below the U.S. statutory tax rate, including the effect of repatriation, as well as the impact of discrete tax matters such as tax legislation, changes in valuation allowances, nontaxable adjustments to contingent acquisition consideration and, starting in 2017, excess tax benefits related to share-based compensation.

The Company is routinely examined by tax authorities in the jurisdictions in which it has significant operations. The Company regularly considers the likelihood of assessments in each of the taxing jurisdictions resulting from examinations. When evaluating the potential imposition of penalties, the Company considers a number of relevant factors under penalty statutes, including appropriate disclosure of the tax return position, the existence of legal authority supporting the Company's position, and reliance on the opinion of professional tax advisors.

The Company reports a liability for unrecognized tax benefits resulting from uncertain tax positions taken or expected to be taken in tax returns. The Company's gross unrecognized tax benefits increased from $65 million at December 31, 2016 to $66 million at June 30, 2017. It is reasonably possible that the total amount of unrecognized tax benefits will decrease between zero and approximately $9 million within the next twelve months due to settlements of audits and expirations of statutes of limitation.

3.     Fiduciary Assets and Liabilities

In its capacity as an insurance broker or agent, the Company collects premiums from insureds and, after deducting its commissions, remits the premiums to the respective insurance underwriters. The Company also collects claims or refunds from underwriters on behalf of insureds. Unremitted insurance premiums and claims proceeds are held by the Company in a fiduciary capacity. Risk and Insurance Services revenue includes interest on fiduciary funds of $9 million and $6 million for the three months ended June 30, 2017 and 2016, respectively, and $17 million and $12 million for the six months ended June 30, 2017 and 2016, respectively. The Consulting segment recorded fiduciary interest income of less than $1 million for each of the three month periods ended June 30, 2017 and 2016, and $1 million for each of the six months ended June 30, 2017 and 2016. Since fiduciary assets are not available for corporate use, they are shown in the consolidated balance sheets as an offset to fiduciary liabilities.

Net uncollected premiums and claims and the related payables amounted to $7.7 billion at June 30, 2017 and $7.0 billion atDecember 31, 2016. The Company is not a principal to the contracts under which the right to receive premiums or the right to receive reimbursement of insured losses arises. Accordingly, net uncollected premiums and claims and the related payables are not assets and liabilities of the Company and are not included in the accompanying consolidated balance sheets.

In certain instances, the Company advances premiums, refunds or claims to insurance underwriters or insureds prior to collection. These advances are made from corporate funds and are reflected in the accompanying consolidated balance sheets as receivables.

4.    Per Share Data

Basic net income per share attributable to the Company is calculated by dividing the after-tax income attributable to the Company by the weighted average number of outstanding shares of the Company’s common stock.

Diluted net income per share attributable to the Company is calculated by dividing the after-tax income attributable to the Company by the weighted average number of outstanding shares of the Company’s common stock, which have been adjusted for the dilutive effect of potentially issuable common shares.

Basic and Diluted EPS Calculation	Three Months Ended June 30,				Six Months Ended June 30,
(In millions, except per share amounts)	2017		2016		2017		2016
Basic weighted average common shares outstanding	514		521		514		521
Dilutive effect of potentially issuable common shares	6		4		7		5
Diluted weighted average common shares outstanding	520		525		521		526
Average stock price used to calculate common stock equivalents	$	75.41	$	64.17	$	73.36	$	60.01

There were 12.4 million and 13.9 million stock options outstanding as of June 30, 2017 and 2016, respectively.

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5.    Supplemental Disclosures to the Consolidated Statements of Cash Flows

The following schedule provides additional information concerning acquisitions, interest and income taxes paid for the six-month periods ended June 30, 2017 and 2016.

(In millions)	2017			2016
Assets acquired, excluding cash	$	576		$	107
Liabilities assumed	(74		)	(4		)
Contingent/deferred purchase consideration	(90		)	(26		)
Net cash outflow for acquisitions	$	412		$	77

(In millions)	2017		2016
Interest paid	$	92	$	86
Income taxes paid, net of refunds	$	297	$	303

The classification of contingent consideration in the statement of cash flows is determined by whether the payment was part of the initial liability established on the acquisition date (financing) or an adjustment to the acquisition date liability (operating).

The following amounts are included in the consolidated statements of cash flows as a financing activity. The Company paid deferred and contingent consideration of $97 million for the six months ended June 30, 2017. This consisted of deferred purchase consideration related to prior years' acquisitions of $37 million and contingent consideration of $60 million. For the six months ended June 30, 2016, the Company paid deferred and contingent consideration of $63 million, consisting of deferred purchase consideration related to prior years' acquisitions of $39 million and contingent consideration of $24 million.

The following amounts are included in the operating section of the consolidated statements of cash flows. For the six months ended June 30, 2017, the Company recorded a net credit for adjustments to acquisition related accounts of $8 million and contingent consideration payments of $5 million. For the six months ended June 30, 2016, the Company recorded a net charge for adjustments related to acquisition related accounts of $18 million and contingent consideration payments of $26 million.

The Company had non-cash issuances of common stock under its share-based payment plan of $87 million and $70 million for the six months ended June 30, 2017 and 2016, respectively. The Company recorded stock-based compensation expense for equity awards related to restricted stock units, performance stock units and stock options of $75 million and $58 million for the six-month periods ended June 30, 2017 and 2016, respectively.

Effective January 1, 2017, the Company adopted new accounting guidance related to share-based compensation, that requires companies to record excess tax benefits and tax deficiencies as an income tax benefit or expense in the income statement and classify excess tax benefits as an operating activity in the statement of cash flows. Prior to the adoption of this standard, the Company recorded excess tax benefits in equity in the consolidated balance sheet and as a financing activity in the consolidated statement of cash flows. For the six months ended June 30, 2017, the adoption of this new standard reduced income tax expense in the consolidated statement of income by approximately $48 million. For the six months ended June 30, 2016, the Company recorded an excess tax benefit of $24 million as an increase to equity in its consolidated balance sheet, which was reflected as cash provided by financing activities in the consolidated statement of cash flows.

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6.    Other Comprehensive Income (Loss)

The changes, net of tax, in the balances of each component of Accumulated Other Comprehensive Income ("AOCI") for the three and six-month periods ended June 30, 2017 and 2016, including amounts reclassified out of AOCI, are as follows:

(In millions)	Unrealized Investment Gains		Pension/Post-Retirement Plans Gains (Losses)			Foreign Currency Translation Gains (Losses)			Total Gains (Losses)
Balance as of April 1, 2017	$	16	$	(3,208	)	$	(1,645	)	$	(4,837	)
Other comprehensive income (loss) before reclassifications	14		(40		)	289			263
Amounts reclassified from accumulated other comprehensive income	—		33			—			33
Net current period other comprehensive income (loss)	14		(7		)	289			296
Balance as of June 30, 2017	$	30	$	(3,215	)	$	(1,356	)	$	(4,541	)

(In millions)	Unrealized Investment Gains		Pension/Post-Retirement Plans Gains (Losses)			Foreign Currency Translation Gains (Losses)			Total Gains (Losses)
Balance as of April 1, 2016	$	6	$	(3,014	)	$	(1,089	)	$	(4,097	)
Other comprehensive income (loss) before reclassifications	—		98			(333		)	(235		)
Amounts reclassified from accumulated other comprehensive income	—		31			—			31
Net current period other comprehensive income (loss)	—		129			(333		)	(204		)
Balance as of June 30, 2016	$	6	$	(2,885	)	$	(1,422	)	$	(4,301	)

(In millions)	Unrealized Investment Gains		Pension/Post-Retirement Plans Gains (Losses)			Foreign Currency Translation Gains (Losses)			Total Gains (Losses)
Balance as of January 1, 2017	$	19	$	(3,232	)	$	(1,880	)	$	(5,093	)
Other comprehensive income (loss) before reclassifications	11		(46		)	524			489
Amounts reclassified from accumulated other comprehensive income	—		63			—			63
Net current period other comprehensive income (loss)	11		17			524			552
Balance as of June 30, 2017	$	30	$	(3,215	)	$	(1,356	)	$	(4,541	)

(In millions)	Unrealized Investment Gains		Pension/Post-Retirement Plans Gains (Losses)			Foreign Currency Translation Gains (Losses)			Total Gains (Losses)
Balance as of January 1, 2016	$	6	$	(3,124	)	$	(1,102	)	$	(4,220	)
Other comprehensive income (loss) before reclassifications	—		178			(320		)	(142		)
Amounts reclassified from accumulated other comprehensive income	—		61			—			61
Net current period other comprehensive income (loss)	—		239			(320		)	(81		)
Balance as of June 30, 2016	$	6	$	(2,885	)	$	(1,422	)	$	(4,301	)

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The components of other comprehensive income (loss) for the three and six-month periods ended June 30, 2017 and 2016 are as follows:

Three Months Ended June 30,	2017									2016
(In millions)	Pre-Tax			Tax (Credit)			Net of Tax			Pre-Tax			Tax (Credit)			Net of Tax
Foreign currency translation adjustments	$	290		$	1		$	289		$	(334	)	$	(1	)	$	(333	)
Unrealized investment gains	24			10			14			—			—			—
Pension/post-retirement plans:
Amortization of losses included in net periodic pension cost:
Net actuarial losses (a)	42			9			33			43			12			31
Subtotal	42			9			33			43			12			31
Effect of remeasurement	—			1			(1		)	—			—			—
Effect of curtailment	—			—			—			3			1			2
Foreign currency translation (losses) gains	(47		)	(8		)	(39		)	116			21			95
Other	—			—			—			1			—			1
Pension/post-retirement plans gains (losses)	(5		)	2			(7		)	163			34			129
Other comprehensive income (loss)	$	309		$	13		$	296		$	(171	)	$	33		$	(204	)
(a) Components of net periodic pension cost are included in compensation and benefits in the consolidated statements of income. Income tax credits on prior service losses and net actuarial losses are included in income tax expense.

Six Months Ended June 30,	2017									2016
(In millions)	Pre-Tax			Tax (Credit)			Net of Tax			Pre-Tax			Tax (Credit)			Net of Tax
Foreign currency translation adjustments	$	525		$	1		$	524		$	(321	)	$	(1	)	$	(320	)
Unrealized investment gains	19			8			11			—			—			—
Pension/post-retirement plans:
Amortization of losses included in net periodic pension cost:
Prior service cost (a)	—			—			—			1			—			1
Net actuarial losses (a)	82			19			63			84			24			60
Subtotal	82			19			63			85			24			61
Effect of remeasurement	9			3			6			(1		)	—			(1		)
Effect of curtailment	(1		)	—			(1		)	3			1			2
Effect of settlement	1			—			1			1			—			1
Foreign currency translation (losses) gains	(62		)	(11		)	(51		)	213			37			176
Other	(1		)	—			(1		)	—			—			—
Pension/post-retirement plans gains	28			11			17			301			62			239
Other comprehensive income (loss)	$	572		$	20		$	552		$	(20	)	$	61		$	(81	)
(a) Components of net periodic pension cost are included in compensation and benefits in the consolidated statements of income. Tax on prior service gains and net actuarial losses is included in income tax expense.

7.     Acquisitions

The Company’s acquisitions have been accounted for as business combinations. Net assets and results of operations are included in the Company’s consolidated financial statements commencing at the respective purchase closing dates. In connection with acquisitions, the Company records the estimated value of the net tangible assets purchased and the value of the identifiable intangible assets purchased, which typically consist of purchased customer lists, developed technology, trademarks and non-compete agreements. The valuation of purchased intangible assets involves significant estimates and assumptions. Until final valuations are complete, any change in assumptions could affect the carrying value of tangible assets, goodwill and identifiable intangible assets.

14

The Risk and Insurance Services segment completed five acquisitions during the first six months of 2017.

• January – Marsh & McLennan Agency ("MMA") acquired J. Smith Lanier & Co. ("JSL"), a privately held insurance brokerage firm providing insurance, risk management, and employee benefits solutions to businesses and individuals throughout the U.S.

• February – MMA acquired iaConsulting Services, a Texas-based employee benefits consulting firm.

• March – MMA acquired Blakestad, Inc., a Minnesota-based private client and commercial lines insurance agency, and RJF Financial Services, a Minnesota-based retirement advisory firm.

• May – MMA acquired Insurance Partners of Texas, a Texas-based employee benefits consulting firm.

Total purchase consideration for acquisitions made during the six months ended June 30, 2017 was $510 million, which consisted of cash paid of $420 million and deferred purchase and estimated contingent consideration of $90 million. Contingent consideration arrangements are based primarily on earnings before interest, tax, depreciation and amortization ("EBITDA") or revenue targets over a period of two to four years. The fair value of the contingent consideration was based on projected revenue or EBITDA of the acquired entities. Estimated fair values of assets acquired and liabilities assumed are subject to adjustment when purchase accounting is finalized. The Company also paid $37 million of deferred purchase consideration and $65 million of contingent consideration related to acquisitions made in prior years.

The following table presents the preliminary allocation of the acquisition cost to the assets acquired and liabilities assumed during 2017 based on their fair values:

For the Six Months Ended June 30, 2017
(In millions)
Cash	$	420
Estimated fair value of deferred/contingent consideration	90
Total Consideration	$	510
Allocation of purchase price:
Cash and cash equivalents	$	8
Accounts receivable, net	7
Property, plant, and equipment	3
Other intangible assets	196
Goodwill	370
Total assets acquired	584
Current liabilities	4
Other liabilities	70
Total liabilities assumed	74
Net assets acquired	$	510

The following chart provides information about other intangible assets acquired during 2017:

	Amount		Weighted Average Amortization Period
Client relationships	$	184	13 years
Other	12		4 years
	$	196

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Prior-Year Acquisitions

The Risk and Insurance Services segment completed nine acquisitions during 2016.

• February – MMA acquired The Celedinas Agency, Inc., a Florida-based brokerage firm, providing property, casualty and marine insurance, as well as employee benefits services, and Aviation Solutions, LLC, a Missouri-based aviation risk advisor and insurance broker.

• March – MMA acquired Corporate Consulting Services, Ltd., a New York-based insurance brokerage and human resource consulting firm.

• August – MMA acquired Benefits Advisory Group LLC, an Atlanta-based employee benefits consulting firm.

• September – MMA acquired Vero Insurance, Inc., a Florida-based agency specializing in private client insurance services.

• November – MMA acquired Benefits Resource Group Agency, LLC, an Ohio-based benefits consulting firm and Presidio Benefits Group, Inc., a California-based employee benefits consulting firm.

• December – Marsh acquired AD Corretora, a multi-line broker located in Brazil, and Bluefin Insurance Group, Ltd, a U.K.-based insurance brokerage.

The Consulting segment completed six acquisitions during 2016.

• January – Mercer acquired The Positive Ageing Company Limited, a U.K.-based firm providing advice on issues surrounding the aging workforce.

• April – Mercer acquired the Extratextual software system and related client contracts. Extratextual is a web based compliance system that assists clients to manage and meet their compliance and risk management obligations.

• December – Oliver Wyman acquired LShift Limited, a software development company, and Mercer acquired Sirota Consulting LLC, a global provider of employee benefit solutions; Pillar Administration, a superannuation provider located in Australia; and Thomsons Online Benefits, a U.K.-based global benefits software business.

Total purchase consideration for acquisitions made during the first six months of 2016 was $105 million, which consisted of cash paid of $79 million and deferred purchase and estimated contingent consideration of $26 million. Contingent consideration arrangements are primarily based on EBITDA or revenue targets over a period of two to four years. The fair value of the contingent consideration was based on projected revenue or earnings of the acquired entities. Estimated fair values of assets acquired and liabilities assumed are subject to adjustment when purchase accounting is finalized. In the first six months of 2016, the Company also paid $39 million of deferred purchase consideration and $50 million of contingent consideration related to acquisitions made in prior years.

Pro-Forma Information

The following unaudited pro-forma financial data gives effect to the acquisitions made by the Company during 2017 and 2016. In accordance with accounting guidance related to pro-forma disclosures, the information presented for current year acquisitions is as if they occurred on January 1, 2016 and reflects acquisitions made in 2016 as if they occurred on January 1, 2015. The unaudited pro-forma information adjusts for the effects of amortization of acquired intangibles. The unaudited pro-forma financial data is presented for illustrative purposes only and is not necessarily indicative of the operating results that would have been achieved if such acquisitions had occurred on the dates indicated, nor is it necessarily indicative of future consolidated results.

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions, except per share figures)	2017		2016		2017		2016
Revenue	$	3,496	$	3,493	$	7,011	$	6,951
Net income attributable to the Company	$	502	$	470	$	1,072	$	950
Basic net income per share attributable to the Company	$	0.98	$	0.90	$	2.08	$	1.82
Diluted net income per share attributable to the Company	$	0.96	$	0.89	$	2.06	$	1.81

The consolidated statements of income include the results of operations of acquired companies since their respective acquisition dates. The consolidated statements of income for the three and six-month periods ended

16

June 30, 2017 include approximately $34 million and$63 million of revenue, respectively, and $5 million and $15 million of operating income, respectively, related to acquisitions made in 2017.

8.    Goodwill and Other Intangibles

The Company is required to assess goodwill and any indefinite-lived intangible assets for impairment annually, or more frequently if circumstances indicate impairment may have occurred. The Company performs the annual impairment assessment for each of its reporting units during the third quarter of each year. In accordance with applicable accounting guidance, the Company assesses qualitative factors to determine whether it is necessary to perform the two-step goodwill impairment test. The Company considers numerous factors, which include whether the fair value of each reporting unit exceeded its carrying value by a substantial margin in its most recent estimate of reporting unit fair values, whether significant acquisitions or dispositions occurred which might alter the fair value of its reporting units, macroeconomic conditions and their potential impact on reporting unit fair values, actual performance compared with budget and prior projections used in its estimation of reporting unit fair values, industry and market conditions, and the year-over-year change in the Company’s share price. The Company completed its qualitative assessment in the third quarter of 2016 and concluded that a two-step goodwill impairment test was not required in 2016 and that goodwill was not impaired.

Changes in the carrying amount of goodwill are as follows:

June 30,
(In millions)	2017		2016
Balance as of January 1, as reported	$	8,369	$	7,889
Goodwill acquired	370		62
Other adjustments(a)	82		(6		)
Balance at June 30,	$	8,821	$	7,945

^(a)  The increase in 2017 primarily reflects the impact of foreign exchange.

Goodwill allocable to the Company’s reportable segments at June 30, 2017 is as follows: Risk and Insurance Services, $6.3 billion and Consulting, $2.5 billion.

Other intangible assets that are not deemed to have an indefinite life are amortized over their estimated lives and reviewed for impairment upon the occurrence of certain triggering events in accordance with applicable accounting literature.

The gross cost and accumulated amortization at June 30, 2017 and December 31, 2016 are as follows:

	June 30, 2017						December 31, 2016
(In millions)	Gross Cost		Accumulated Amortization		Net Carrying Amount		Gross Cost		Accumulated Amortization		Net Carrying Amount
Client Relationships	$	1,581	$	453	$	1,128	$	1,390	$	392	$	998
Other (a)	198		93		105		204		76		128
Amortized intangibles	$	1,779	$	546	$	1,233	$	1,594	$	468	$	1,126

^(a) Primarily non-compete agreements, trade names and developed technology.

Aggregate amortization expense for the six months ended June 30, 2017 and2016 was $80 million and $67 million, respectively. The estimated future aggregate amortization expense is as follows:

For the Years Ending December 31,
(In millions)	Estimated Expense
2017 (excludes amortization through June 30, 2017)	$	85
2018	158
2019	149
2020	127
2021	118
Subsequent years	596
	$	1,233

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9.     Fair Value Measurements

Fair Value Hierarchy

The Company has categorized its assets and liabilities that are valued at fair value on a recurring basis into a three-level fair value hierarchy as defined by the Financial Accounting Standards Board ("FASB"). The fair value hierarchy gives the highest priority to quoted prices in active markets for identical assets and liabilities (Level 1) and lowest priority to unobservable inputs (Level 3). In some cases, the inputs used to measure fair value might fall into different levels of the fair value hierarchy. In such cases, the level in the fair value hierarchy, for disclosure purposes, is determined based on the lowest level input that is significant to the fair value measurement. Assets and liabilities recorded in the consolidated balance sheets at fair value are categorized based on the inputs in the valuation techniques as follows:

Level 1. Assets and liabilities whose values are based on unadjusted quoted prices for identical assets or liabilities in an active market (examples include active exchange-traded equity securities and exchange-traded money market mutual funds).

Assets and liabilities measured using Level 1 inputs include exchange-traded equity securities, exchange-traded mutual funds and money market funds.

Level 2. Assets and liabilities whose values are based on the following:

a) Quoted prices for similar assets or liabilities in active markets;

b) Quoted prices for identical or similar assets or liabilities in non-active markets (examples include corporate and municipal bonds, which trade infrequently);

c) Pricing models whose inputs are observable for substantially the full term of the asset or liability (examples include most over-the-counter derivatives, including interest rate and currency swaps); and

d) Pricing models whose inputs are derived principally from or corroborated by observable market data through correlation or other means for substantially the full asset or liability (for example, certain mortgage loans).

The Company does not have any assets or liabilities that are measured using Level 2 inputs.

Level 3. Assets and liabilities whose values are based on prices, or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement. These inputs reflect management’s own assumptions about the assumptions a market participant would use in pricing the asset or liability.

Liabilities measured using Level 3 inputs include liabilities for contingent purchase consideration.

Valuation Techniques

Equity Securities, Money Market Funds and Mutual Funds – Level 1

Investments for which market quotations are readily available are valued at the sale price on their principal exchange or, for certain markets, official closing bid price. Money market funds are valued using a valuation technique that results in price per share at $1.00.

Contingent Purchase Consideration Liability – Level 3

Purchase consideration for some acquisitions made by the Company includes contingent consideration arrangements. These arrangements typically provide for the payment of additional consideration if earnings or revenue targets are met over periods from two to four years. The fair value of the contingent purchase consideration liability is estimated as the present value of future cash flows to be paid, based on projections of revenue and earnings and related targets of the acquired entities.

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The following fair value hierarchy table presents information about the Company’s assets and liabilities measured at fair value on a recurring basis as of June 30, 2017 and December 31, 2016.

	Identical Assets (Level 1)				Observable Inputs (Level 2)				Unobservable Inputs (Level 3)				Total
(In millions)	06/30/17		12/31/16		06/30/17		12/31/16		06/30/17		12/31/16		06/30/17		12/31/16
Assets:
Financial instruments owned:
Exchange traded equity securities(a)	$	107	$	89	$	—	$	—	$	—	$	—	$	107	$	89
Mutual funds(a)	140		141		—		—		—		—		140		141
Money market funds(b)	36		22		—		—		—		—		36		22
Total assets measured at fair value	$	283	$	252	$	—	$	—	$	—	$	—	$	283	$	252
Fiduciary Assets:
Money market funds	$	82	$	90	$	—	$	—	$	—	$	—	$	82	$	90
Total fiduciary assets measured at fair value	$	82	$	90	$	—	$	—	$	—	$	—	$	82	$	90
Liabilities:
Contingent purchase consideration liability(c)	$	—	$	—	$	—	$	—	$	203	$	241	$	203	$	241
Total liabilities measured at fair value	$	—	$	—	$	—	$	—	$	203	$	241	$	203	$	241

^(a)  Included in other assets in the consolidated balance sheets.

^(b)  Included in cash and cash equivalents in the consolidated balance sheets.

^(c)  Included in accounts payable and accrued liabilities and other liabilities in the consolidated balance sheets.

During the six-month period ended June 30, 2017, there were no assets or liabilities that were transferred between any of the levels.

The table below sets forth a summary of the changes in fair value of the Company’s Level 3 liabilities as of June 30, 2017 and 2016 that represent contingent consideration related to acquisitions:

(In millions)	2017			2016
Balance at January 1,	$	241		$	309
Additions	34			8
Payments	(65		)	(50		)
Revaluation Impact	(8		)	18
Other (a)	1			(6		)
Balance at June 30,	$	203		$	279

^(a) Primarily reflects the impact of foreign exchange.

The fair value of the contingent purchase consideration liability is based on projections of revenue and EBITDA for the acquired entities in relation to the established targets and are reassessed on a quarterly basis. As set forth in the table above, based on the Company's ongoing assessment of the fair value of contingent consideration, the Company recorded a net decrease in the estimated fair value of such liabilities for prior-period acquisitions of $8 million in the six-month period ended June 30, 2017. A 5% increase in the above mentioned projections would increase the liability by approximately $19 million. A 5% decrease in the above mentioned projections would decrease the liability by approximately $22 million.

Long-Term Investments

The Company holds investments in certain private equity investments, public companies and private companies that are accounted for using the equity method of accounting. The carrying value of these investments was $416 million and $389 million at June 30, 2017 and December 31, 2016, respectively.

19

Private Equity Investments

The Company's investments in private equity investments were $76 million and $79 million at June 30, 2017 and December 31, 2016, respectively. The carrying values of these private equity investments approximate fair value. The underlying private equity funds follow investment company accounting, where investments within the fund are carried at fair value. The Company records in earnings, investment gains/losses for its proportionate share of the change in fair value of the funds. These investments are included in other assets in the consolidated balance sheets.

Investments in Public and Private Companies

Alexander Forbes: The Company owns approximately 33% of the common stock of Alexander Forbes, a South African company listed on the Johannesburg Stock Exchange, which it purchased in 2014 for 7.50 South African Rand per share. As of June 30, 2017, the carrying value of the Company’s investment in Alexander Forbes was approximately $275 million. As of June 30, 2017, the market value of the approximately 443 million shares of Alexander Forbes owned by the Company, based on the June 30, 2017 closing share price of 6.95 South African Rand per share, was approximately $237 million. During the first six months of 2017, the daily closing share price ranged between 5.99 Rand (in late April) and 7.95 Rand (in early January). During the month of June 2017, Alexander Forbes stock price ranged from 6.25 Rand on June 1 to a high of 7.31 Rand on June 23. The Company considered several factors related to its investment in Alexander Forbes, including its financial position, the near- and long-term prospects of Alexander Forbes and the broader South African economy and capital markets, the length of time and extent to which the market value was below cost and the Company’s intent and ability to retain the investment for a sufficient period of time to allow for anticipated recovery in market value. As a result, the Company determined the investment was not impaired.

The Company’s investment in Alexander Forbes and its other equity investments in private insurance and consulting companies are accounted for using the equity method of accounting, the results of which are included in revenue in the consolidated statements of income and the carrying value of which is included in other assets in the consolidated balance sheets. The Company records its share of income or loss on its equity method investments on a one quarter lag basis.

Benefitfocus: On February 24, 2015, the Company purchased shares of common stock of Benefitfocus (NASDAQ:BNFT) constituting 9.9% of BNFT's outstanding capital stock as of the acquisition date. The purchase price for the BNFT shares and certain other rights and other consideration was approximately $75 million. Until December 31, 2016, the Company accounted for this investment under the cost method of accounting as the shares purchased were categorized as restricted. Effective December 31, 2016, these shares were no longer considered restricted for the purpose of determining if they are marketable securities under applicable accounting guidance, and are now accounted for as available for sale securities and included in other assets in the consolidated balance sheets. The value of the BNFT shares based on the closing price on the NASDAQ as of June 30, 2017 was approximately $102 million. During the first six months of 2017 an unrealized gain related to these shares of approximately $19 million was recorded in other comprehensive income.

10.    Retirement Benefits

The Company maintains qualified and non-qualified defined benefit pension plans for some of its U.S. and non-U.S. eligible employees. The Company’s policy for funding its tax-qualified defined benefit pension plans is to contribute amounts at least sufficient to meet the funding requirements set forth by U.S. law and the laws of the non-U.S. jurisdictions in which the Company offers such plans.

The target asset allocation for the Company's U.S. Plan was 64% equities and equity alternatives and 36% fixed income and at June 30, 2017, the actual allocation for the Company's U.S. Plan was 64% equities and equity alternatives and 36% fixed income. The target asset allocation for the Company's U.K. Plans, which comprise approximately 81% of non-U.S. plan assets at December 31, 2016, was46% equities and equity alternatives and 54% fixed income. At June 30, 2017, the actual allocation for the U.K. Plans was 46% equities and equity alternatives and 54% fixed income. The assets of the Company's defined benefit plans are diversified and are managed in accordance with applicable laws and with the goal of maximizing the plans' real return within acceptable risk parameters. The Company generally uses threshold-based portfolio re-balancing to ensure the actual portfolio remains consistent with target asset allocation ranges.

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The components of the net periodic benefit cost for defined benefit and other post-retirement plans are as follows:

Combined U.S. and significant non-U.S. plans	Pension Benefits						Post-retirement Benefits
For the Three Months Ended June 30,
(In millions)	2017			2016			2017			2016
Service cost	$	19		$	46		$	—		$	—
Interest cost	124			138			1			1
Expected return on plan assets	(230		)	(242		)	—			—
Amortization of prior service cost (credit)	(1		)	(1		)	—			1
Recognized actuarial loss	43			42			—			—
Net periodic benefit (credit) cost	$	(45	)	$	(17	)	$	1		$	2
Curtailment gain	—			(5		)	—			—
Settlement loss	—			1			—			—
Total (credit) cost	$	(45	)	$	(21	)	$	1		$	2
Combined U.S. and significant non-U.S. plans	Pension Benefits						Post-retirement Benefits
For the Six Months Ended June 30,
(In millions)	2017			2016			2017			2016
Service cost	$	37		$	90		$	—		$	—
Interest cost	246			275			2			3
Expected return on plan assets	(454		)	(483		)	—			—
Amortization of prior service cost (credit)	(1		)	(1		)	1			2
Recognized actuarial loss (gain)	83			84			—			(1		)
Net periodic benefit (credit) cost	$	(89	)	$	(35	)	$	3		$	4
Curtailment gain	(1		)	(5		)	—			—
Settlement loss	1			1			—			—
Total (credit) cost	$	(89	)	$	(39	)	$	3		$	4
U.S. Plans only	Pension Benefits						Post-retirement Benefits
For the Three Months Ended June 30,
(In millions)	2017			2016			2017			2016
Service cost	$	—		$	27		$	—		$	—
Interest cost	66			66			1			—
Expected return on plan assets	(90		)	(95		)	—			—
Amortization of prior service cost	—			—			1			1
Recognized actuarial loss (gain)	10			18			(1		)	—
Net periodic benefit (credit) cost	$	(14	)	$	16		$	1		$	1

U.S. Plans only	Pension Benefits						Post-retirement Benefits
For the Six Months Ended June 30,
(In millions)	2017			2016			2017			2016
Service cost	$	—		$	53		$	—		$	—
Interest cost	132			132			1			1
Expected return on plan assets	(179		)	(190		)	—			—
Amortization of prior service cost	—			—			2			2
Recognized actuarial loss (gain)	19			36			(1		)	(1		)
Net periodic benefit (credit) cost	$	(28	)	$	31		$	2		$	2

21

In October 2016, the Company modified its U.S. defined benefit pension plans to discontinue further benefit accruals for participants after December 31, 2016. At the same time, the Company amended its U.S. defined contribution retirement plans for most of its U.S. employees to add an automatic Company contribution equal to 4% of eligible base pay beginning on January 1, 2017. This new Company contribution, together with the Company’s current matching contribution, provides eligible U.S. employees with the opportunity to receive a total contribution of up to 7% of eligible base pay. In addition, the U.S. qualified defined benefit plans were merged effective December 30, 2016.

Significant non-U.S. plans only	Pension Benefits						Post-retirement Benefits
For the Three Months Ended June 30,
(In millions)	2017			2016			2017			2016
Service cost	$	19		$	19		$	—		$	—
Interest cost	58			72			—			1
Expected return on plan assets	(140		)	(147		)	—			—
Amortization of prior service credit	(1		)	(1		)	(1		)	—
Recognized actuarial loss	33			24			1			—
Net periodic benefit (credit) cost	$	(31	)	$	(33	)	$	—		$	1
Curtailment gain	—			(5		)	—			—
Settlement loss	—			1			—			—
Total (credit) cost	$	(31	)	$	(37	)	$	—		$	1

Significant non-U.S. plans only	Pension Benefits						Post-retirement Benefits
For the Six Months Ended June 30,
(In millions)	2017			2016			2017			2016
Service cost	$	37		$	37		$	—		$	—
Interest cost	114			143			1			2
Expected return on plan assets	(275		)	(293		)	—			—
Amortization of prior service credit	(1		)	(1		)	(1		)	—
Recognized actuarial loss	64			48			1			—
Net periodic benefit (credit) cost	$	(61	)	$	(66	)	$	1		$	2
Curtailment gain	(1		)	(5		)	—			—
Settlement loss	1			1			—			—
Total (credit) cost	$	(61	)	$	(70	)	$	1		$	2

In March 2017, the Company modified its defined benefit pension plans in Canada to discontinue further benefit accruals for participants after December 31, 2017 and replaced them with a defined contribution arrangement. The Company also amended its post-retirement benefits plan in Canada so that individuals who retire after April 1, 2019 will not be eligible to participate, except in certain situations. The Company re-measured the assets and liabilities of the plans, based on assumptions and market conditions on the amendment date.

The weighted average actuarial assumptions utilized to calculate the net periodic benefit costs for the U.S. and significant non-U.S. defined benefit plans are as follows:

Combined U.S. and significant non-U.S. plans	Pension Benefits				Post-retirement Benefits
June 30,	2017		2016		2017		2016
Weighted average assumptions:
Expected return on plan assets	6.64	%	7.07	%	—		—
Discount rate	3.40	%	4.11	%	3.64	%	4.12	%
Rate of compensation increase*	1.77	%	2.44	%	—		—

*The 2017 assumption does not include a rate of compensation increase for the U.S. defined benefit plans since future benefit accruals were discontinued for those plans after December 31, 2016.

22

The Company made approximately $120 million of contributions to its U.S. and non-U.S. defined benefit plans in the first six months of 2017. The Company expects to contribute approximately $136 million to its U.S. pension and non-U.S. pension plans during the remainder of 2017.

Defined Contribution Plans

The Company maintains certain defined contribution plans for its employees, the most significant being in the U.S. and the U.K. The cost of these U.S. and U.K. defined contribution plans was $65 million and $38 million for the six months ended June 30,2017 and 2016, respectively.

11.    Debt

The Company’s outstanding debt is as follows:

(In millions)	June 30, 2017		December 31, 2016
Short-term:
Commercial paper	$	150	$	50
Current portion of long-term debt	12		262
	162		312
Long-term:
Senior notes – 2.30% due 2017	—		250
Senior notes – 2.55% due 2018	249		249
Senior notes – 2.35% due 2019	299		299
Senior notes – 2.35% due 2020	498		497
Senior notes – 4.80% due 2021	498		498
Senior notes – 2.75% due 2022	496		—
Senior notes – 3.30% due 2023	347		347
Senior notes – 4.05% due 2023	248		248
Senior notes – 3.50% due 2024	596		596
Senior notes – 3.50% due 2025	496		495
Senior notes – 3.75% due 2026	596		596
Senior notes – 5.875% due 2033	297		297
Senior notes – 4.35% due 2047	492		—
Mortgage – 5.70% due 2035	376		382
Other	3		3
	5,491		4,757
Less current portion	12		262
	$	5,479	$	4,495

The senior notes in the table above are registered by the Company with the Securities and Exchange Commission and are not guaranteed.

The Company has established a short-term debt financing program of up to $1.5 billion through the issuance of commercial paper. The proceeds from the issuance of commercial paper are used for general corporate purposes. The Company had $150 million of commercial paper outstanding at June 30, 2017 at an effective interest rate of 1.45%.

In January 2017, the Company issued $500 million of 2.75% senior notes due 2022 and $500 million of 4.35% senior notes due 2047. The Company used the net proceeds for general corporate purposes, including the repayment of a $250 million debt maturity in April 2017.

In March 2016, the Company issued $350 million of 3.30%seven-year senior notes. The Company used the net proceeds for general corporate purposes.

The Company and certain of its foreign subsidiaries maintain a $1.5 billion multi-currency five-year unsecured revolving credit facility. The interest rate on this facility is based on LIBOR plus a fixed margin which varies with the Company's credit ratings. This facility expires in November 2020 and requires the Company to maintain certain

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coverage and leverage ratios which are tested quarterly. There were no borrowings outstanding under this facility at June 30, 2017.

Fair Value of Short-term and Long-term Debt

The estimated fair value of the Company’s short-term and long-term debt is provided below. Certain estimates and judgments were required to develop the fair value amounts. The fair value amounts shown below are not necessarily indicative of the amounts that the Company would realize upon disposition, nor do they indicate the Company’s intent or need to dispose of the financial instrument.

	June 30, 2017				December 31, 2016
(In millions)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Short-term debt	$	162	$	162	$	312	$	313
Long-term debt	$	5,479	$	5,714	$	4,495	$	4,625

The fair value of the Company’s short-term debt consists primarily of commercial paper and term debt maturing within the next year and its fair value approximates its carrying value. The estimated fair value of a primary portion of the Company's long-term debt is based on discounted future cash flows using current interest rates available for debt with similar terms and remaining maturities. Short- and long-term debt would be classified as Level 2 in the fair value hierarchy.

12.    Restructuring Costs

The Company recorded total restructuring costs of $24 million in the first six months of 2017, primarily for severance at Mercer and future rent under non-cancelable leases. These costs were incurred in Risk and Insurance Services ($4 million), Consulting ($16 million) and Corporate ($4 million).

Details of the restructuring activity from January 1, 2016 through June 30, 2017, which includes liabilities from actions prior to 2017, are as follows:

(In millions)	Liability at 1/1/16		Amounts Accrued		Cash Paid			Other			Liability at 12/31/16		Amounts Accrued		Cash Paid			Other			Liability at 6/30/17
Severance	$	15	$	40	$	(22	)	$	(1	)	$	32	$	19	$	(30	)	$	(2	)	$	19
Future rent under non-cancelable leases and other costs	78		4		(17		)	(4		)	61		5		(9		)	(2		)	55
Total	$	93	$	44	$	(39	)	$	(5	)	$	93	$	24	$	(39	)	$	(4	)	$	74

The expenses associated with the above initiatives are included in compensation and benefits and other operating expenses in the consolidated statements of income. The liabilities associated with these initiatives are classified on the consolidated balance sheets as accounts payable and accrued liabilities, other liabilities or accrued compensation and employee benefits, depending on the nature of the items.

13.    Common Stock

During the first six months of 2017, the Company repurchased approximately 5.4 million shares of its common stock for consideration of $400 million. During the first six months of 2016, the Company repurchased approximately 7.0 million shares of its common stock for consideration of $425 million. In November 2016, the Board of Directors of the Company authorized the Company to repurchase up to $2.5 billion in shares of the Company's common stock, which superseded any prior authorizations. As of June 30, 2017, the Company remained authorized to repurchase up to approximately $2 billion in shares of its common stock. There is no time limit on the authorization.

The Company issued approximately 3.7 million and 4.1 million shares related to stock compensation and employee stock purchase plans during the first six months of 2017 and 2016, respectively.

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14.    Claims, Lawsuits and Other Contingencies

Litigation Matters

The Company and its subsidiaries are subject to a significant number of claims, lawsuits and proceedings in the ordinary course of business. Such claims and lawsuits consist principally of alleged errors and omissions in connection with the performance of professional services, including the placement of insurance, the provision of actuarial services for corporate and public sector clients, the provision of investment advice and investment management services to pension plans, the provision of advice relating to pension buy-out transactions and the provision of consulting services relating to the drafting and interpretation of trust deeds and other documentation governing pension plans. These claims typically seek damages, including punitive and treble damages, in amounts that could be significant. In establishing liabilities for errors and omissions claims in accordance with FASB ASC Subtopic No. 450-20 (Contingencies-Loss Contingencies), the Company uses case level reviews by inside and outside counsel, and internal actuarial analysis by Oliver Wyman Group, a subsidiary of the Company, and other methods to estimate potential losses. A liability is established when a loss is both probable and reasonably estimable. The liability is reviewed quarterly and adjusted as developments warrant. In many cases, the Company has not recorded a liability, other than for legal fees to defend the claim, because we are unable, at the present time, to make a determination that a loss is both probable and reasonably estimable.

To the extent that expected losses exceed our deductible in any policy year, the Company also records an asset for the amount that we expect to recover under any available third-party insurance programs. The Company has varying levels of third-party insurance coverage, with policy limits and coverage terms varying significantly by policy year.

Governmental Inquiries and Enforcement Matters

Our activities are regulated under the laws of the United States and its various states, the European Union and its member states, and the other jurisdictions in which the Company operates.

In April 2017, the Financial Conduct Authority in the United Kingdom (the "FCA") commenced a civil competition investigation into the aviation insurance and reinsurance sector. In connection with that investigation, the FCA carried out an on-site inspection at the London office of Marsh Limited, our Marsh and Guy Carpenter operating subsidiary in the United Kingdom. The FCA indicated that it had reasonable grounds for suspecting that Marsh Limited and other participants in the market have been sharing competitively sensitive information within the aviation insurance and reinsurance broking sector.

In July 2017, the Directorate-General for Competition of the European Commission and the Irish Competition and Consumer Protection Commission conducted on-site inspections at the offices of Marsh and other brokers in Dublin in connection with an investigation into potential anti-competitive practices in the commercial motor insurance market in the Republic of Ireland.

We are cooperating fully with these investigations and are conducting our own reviews. As these investigations are at early stages, we are unable to predict their likely timing, outcome or ultimate impact. There can be no assurance that the ultimate resolution of these or any related matters will not have a material adverse effect on our consolidated financial position, results of operations or liquidity.

In June 2017, the FCA issued a final report in connection with a market study of the U.K. asset management industry, which includes asset managers and investment consultants, including Mercer. In its report, the FCA indicated it would likely make a market investigation referral with respect to the investment consulting industry to the U.K. Competition & Markets Authority (the "CMA"). The FCA expects to announce a final decision regarding its referral to the CMA in September 2017.

In the ordinary course of business, the Company is also subject to other investigations, subpoenas, lawsuits and other regulatory actions undertaken by governmental authorities.

Other Contingencies-Guarantees

In connection with its acquisition of U.K.-based Sedgwick Group in 1998, the Company acquired several insurance underwriting businesses that were already in run-off, including River Thames Insurance Company Limited ("River Thames"), which the Company sold in 2001. Sedgwick guaranteed payment of claims on certain policies underwritten through the Institute of London Underwriters (the "ILU") by River Thames. The policies covered by this guarantee were reinsured up to £40 million by a related party of River Thames. Payment of claims under the reinsurance agreement is collateralized by segregated assets held in a trust. As of June 30, 2017, the reinsurance coverage exceeded the best estimate of the projected liability of the policies covered by the guarantee. To the

25

extent River Thames or the reinsurer is unable to meet its obligations under those policies, a claimant may seek to recover from the Company under the guarantee.

From 1980 to 1983, the Company owned indirectly the English & American Insurance Company ("E&A"), which was a member of the ILU. The ILU required the Company to guarantee a portion of E&A's obligations. After E&A became insolvent in 1993, the ILU agreed to discharge the guarantee in exchange for the Company's agreement to post an evergreen letter of credit that is available to pay claims by policyholders on certain E&A policies issued through the ILU and incepting between July 3, 1980 and October 6, 1983. Certain claims have been paid under the letter of credit and the Company anticipates that additional claimants may seek to recover against the letter of credit.

* * * *

The pending proceedings described above and other matters not explicitly described in this Note 14 on Claims, Lawsuits and Other Contingencies may expose the Company or its subsidiaries to liability for significant monetary damages, fines, penalties or other forms of relief. Where a loss is both probable and reasonably estimable, the Company establishes liabilities in accordance with FASB ASC Subtopic No. 450-20 (Contingencies - Loss Contingencies). Except as described above, the Company is not able at this time to provide a reasonable estimate of the range of possible loss attributable to these matters or the impact they may have on the Company's consolidated results of operations, financial position or cash flows. This is primarily because these matters are still developing and involve complex issues subject to inherent uncertainty. Adverse determinations in one or more of these matters could have a material impact on the Company's consolidated results of operations, financial condition or cash flows in a future period.

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15.    Segment Information

The Company is organized based on the types of services provided. Under this structure, the Company’s segments are:

▪ Risk and Insurance Services, comprising insurance services (Marsh) and reinsurance services (Guy Carpenter); and

▪ Consulting, comprising Mercer and Oliver Wyman Group.

The accounting policies of the segments are the same as those used for the consolidated financial statements described in Note 1 to the Company’s 2016 Form 10-K. Segment performance is evaluated based on segment operating income, which includes directly related expenses, and charges or credits related to integration and restructuring but not the Company’s corporate-level expenses. Revenues are attributed to geographic areas on the basis of where the services are performed.

Selected information about the Company’s operating segments for the three and six-month periods ended June 30, 2017 and 2016 are as follows:

	Three Months Ended June 30,							Six Months Ended June 30,
(In millions)	Revenue				Operating Income (Loss)			Revenue				Operating Income (Loss)
2017–
Risk and Insurance Services	$	1,916		(a)	$	528		$	3,905		(c)	$	1,141
Consulting	1,592			(b)	283			3,118			(d)	524
Total Operating Segments	3,508				811			7,023				1,665
Corporate / Eliminations	(13		)		(47		)	(25		)		(92		)
Total Consolidated	$	3,495			$	764		$	6,998			$	1,573
2016–
Risk and Insurance Services	$	1,850		(a)	$	490		$	3,718		(c)	$	1,025
Consulting	1,539			(b)	285			3,017			(d)	530
Total Operating Segments	3,389				775			6,735				1,555
Corporate / Eliminations	(13		)		(49		)	(23		)		(96		)
Total Consolidated	$	3,376			$	726		$	6,712			$	1,459

^(a)  Includes inter-segment revenue of $4 million and $3 million in 2017and2016, respectively, interest income on fiduciary funds of $9 million and $6 million in 2017 and 2016, respectively, and equity method income of $7 million and $6 million in 2017 and 2016, respectively.

^(b)  Includes inter-segment revenue of $9 million and $10 million in 2017 and 2016, respectively, interest income on fiduciary funds of less than $1 million in both 2017 and 2016, and equity method income of $5 million in both 2017 and 2016.

^(c)  Includes inter-segment revenue of $4 million in both 2017 and 2016, interest income on fiduciary funds of $17 million and $12 million in 2017 and 2016, respectively, and equity method income of $9 million and $7 million in 2017 and 2016, respectively.

^(d)  Includes inter-segment revenue of $21 million and $19 million in 2017 and 2016, respectively, interest income on fiduciary funds of $1 million in both 2017 and 2016, and equity method income of $9 million in both 2017 and 2016.

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Details of operating segment revenue for the three and six month period ended June 30, 2017 and 2016 are as follows:

	Three Months Ended June 30,						Six Months Ended June 30,
(In millions)	2017			2016			2017			2016
Risk and Insurance Services
Marsh	$	1,621		$	1,564		$	3,223		$	3,057
Guy Carpenter	295			286			682			661
Total Risk and Insurance Services	1,916			1,850			3,905			3,718
Consulting
Mercer	1,109			1,079			2,186			2,118
Oliver Wyman Group	483			460			932			899
Total Consulting	1,592			1,539			3,118			3,017
Total Operating Segments	3,508			3,389			7,023			6,735
Corporate / Eliminations	(13		)	(13		)	(25		)	(23		)
Total	$	3,495		$	3,376		$	6,998		$	6,712

16.    New Accounting Guidance

In March 2017, the FASB issued new guidance that changes the presentation of net periodic pension cost and net periodic postretirement cost (''net periodic benefit costs"). The new guidance requires employers to report the service cost component of net periodic benefit costs in the same line item as other compensation costs in the income statement. The other components of net periodic benefit costs are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations, if one is presented. In addition, only the service cost component is eligible for capitalization, when applicable. The guidance is effective for annual periods beginning after December 15, 2017, including interim periods within those annual periods. Early adoption is permitted as of the beginning of an annual period for which financial statements (interim or annual) have not been issued or made available for issuance. The new guidance requires retrospective application for the presentation of the service cost component and the other components of net periodic benefit costs, and prospective application for the capitalization of the service cost component. The adoption of this guidance will impact the presentation of the Company's results of operations, in particular, reducing net operating income, but will have no impact on the Company's net income.

In January 2017, the FASB issued new guidance to simplify the test for goodwill impairment. The new guidance eliminates the second step in the current two-step goodwill impairment process, under which a goodwill impairment loss is measured by comparing the implied fair value of a reporting unit's goodwill with the carrying amount of that goodwill for that reporting unit. The new guidance requires a one-step impairment test, in which the goodwill impairment charge is based on 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. An entity still has the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. The guidance should be applied on a prospective basis with the nature of and reason for the change in accounting principle disclosed upon transition. The guidance is effective for annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted. The Company does not expect the adoption of this standard to have a material impact on the Company's financial position or results of operations.

In January 2017, the FASB issued guidance which clarifies the definition of a business in order to assist companies with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The guidance is effective for annual periods beginning after December 15, 2017, including interim periods within those annual periods. Early adoption is permitted under certain circumstances and the guidance must be applied prospectively as of the beginning of the period of adoption. The Company is currently evaluating the impact, if any, the adoption of this standard will have on its financial position or results of operations.

In November 2016, the FASB issued new guidance which requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents and amounts generally described as restricted cash or restricted cash equivalents. As a result, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-

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of-period total amounts shown on the statement of cash flows. The new guidance is effective for public companies for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The guidance must be applied retrospectively to all periods presented. Early adoption is permitted. The adoption of this guidance is not expected to have an impact on the Company's consolidated balance sheets or consolidated statements of cash flows.

In October 2016, the FASB also issued new guidance which requires an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. The new guidance eliminates the exception for an intra-entity transfer of an asset other than inventory. The new guidance is effective for public companies for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Early adoption is permitted. The new guidance must be applied on a modified retrospective basis through a cumulative-effect adjustment to retained earnings as of the beginning of the period of adoption. The Company is currently evaluating the impact the adoption of this standard will have on its financial position and results of operations.

In August 2016, the FASB issued new guidance which adds or clarifies guidance on the classification of certain cash receipts and payments in the statement of cash flows, including cash payments for debt prepayments or debt extinguishment costs, contingent consideration payments made after a business combination and distributions received from equity method investees. The guidance is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The guidance must be applied retrospectively to all periods presented unless retrospective application is impracticable. Early adoption is permitted. The Company is currently evaluating the impact the guidance will have on its statement of cash flows.

In February 2016, the FASB issued new guidance intended to improve financial reporting for leases. Under the new guidance, a lessee will be required to recognize assets and liabilities for leases with lease terms of more than 12 months. Consistent with current GAAP, the recognition, measurement, and presentation of expenses and cash flows arising from a lease by a lessee primarily will depend on its classification as a financing or operating lease. However, unlike current GAAP, which requires that only capital leases be recognized on the balance sheet, the new guidance requires that both types of leases be recognized on the balance sheet. The new guidance will require additional disclosures to help investors and other financial statement users better understand the amount, timing, and uncertainty of cash flows arising from leases. These disclosures include qualitative and quantitative requirements, and additional information about the amounts recorded in the financial statements. The accounting by organizations that own the assets ("lessor") leased by the lessee will remain largely unchanged from current GAAP. However, the guidance contains some targeted improvements that are intended to align, where necessary, lessor accounting with the lessee accounting model and with the updated revenue recognition guidance issued in 2014. The new guidance on leases will take effect for public companies for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early application will be permitted. The Company is currently evaluating the impact the adoption of the guidance will have on its financial position and results of operations, but expects material "right to use" assets and lease liabilities to be recorded on its consolidated balance sheets.

In January 2016, the FASB issued new guidance intended to improve the recognition and measurement of financial instruments. The new guidance requires equity investments (except those accounted for under the equity method of accounting, or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income; requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes; requires separate presentation of financial assets and financial liabilities by measurement category and form of financial asset (i.e., securities or loans and receivables) on the balance sheet or the accompanying notes to the financial statements; eliminates the requirement for public business entities to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet; and requires a reporting organization to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk (also referred to as "own credit") when the organization has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. The new guidance is effective for public companies for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The Company is currently evaluating the impact of the adoption of the guidance on its financial position and results of operations.

New Revenue Recognition Pronouncement

In May 2014, the FASB issued new accounting guidance to clarify the principles for revenue recognition. The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in

29

exchange for those goods or services. To achieve that principle, the entity should apply the following steps: identify the contract(s) with the customer, identify the performance obligations in the contract(s), determine the transaction price, allocate the transaction price to the performance obligations in the contract and recognize revenue when (or as) the entity satisfies a performance obligation. Entities are permitted to adopt the guidance under one of the following methods: the "full retrospective" method, which applies the guidance to each period presented (prior years restated) or the "modified retrospective" method in which the guidance is only applied to the year of adoption, with the cumulative effect of initially applying the guidance recognized as an adjustment to retained earnings. The Company will adopt the new guidance effective January 1, 2018. The Company is evaluating the transition method it will use, but currently expects to use the modified retrospective method.

The Company continues to evaluate the impact of the new standard. Based on the results of our reviews to date, the Company expects there will be significant movement in the quarterly timing of revenue recognition in the Risk and Insurance Services segment. In particular, in the Company’s reinsurance broking operations recognition of revenue will be accelerated under the new standard. Currently, revenue related to certain reinsurance placements is recognized on the later of billing or effective date as premiums are written and attached to the reinsurance treaties. This typically results in revenue being recognized over a 12 to 24 month period. Under the new guidance, revenue will be recognized largely at the policy effective date, subject to the constraint as defined in the guidance. In the insurance brokerage operations, revenue from commission based arrangements will continue to be recorded at the policy effective date, while the timing of revenue recognition for certain fee based arrangements will shift among quarters. Since the vast majority of our fee arrangements involve contracts that cover a single year of services, the Company does not believe there will be a significant change to the amount of revenue recognized in an annual period once the standard is adopted. The Company is currently evaluating, designing and implementing changes in processes, controls and systems necessary to support the new revenue recognition requirements.

The Company's initial review and preliminary conclusions for the Consulting segment indicate the application of the new standard will not materially change the existing timing of revenue recognition in quarterly or annual periods. The conclusions will be completed following a final review of customer arrangement legal terms and conditions in certain non-U.S. locations.

The Company expects that certain costs that are currently expensed will be capitalized as costs to obtain or costs to fulfill customer contracts under guidance issued as part of the revenue recognition standard. Costs to obtain a contract, generally, would be amortized over the expected life of the underlying customer relationship. However, in many cases, costs to obtain a contract renewal are commensurate with the costs to obtain the initial contract. Those costs would have an amortization period of less than one year, and the Company would expect to use the practical expedient available in the standard and expense such costs as incurred. Any capitalized costs to fulfill a contract would be amortized on a basis consistent with the transfer of services to which they relate. Such expenses related to Risk and Insurance Services would generally be "amortized" over a period of one year or less. The Company is continuing to quantify the amount of such costs that must be deferred. In the Consulting segment, certain implementation expenses that are currently deferred may have a longer amortization period to reflect the amortization over the expected life of the contract including anticipated renewal periods.

The Company has not yet fully quantified the impact of the changes discussed above. However, the Company expects that it will recognize a significant amount of contract assets and/or receivables upon implementation of the standard, related to both the contract assets for capitalized costs to obtain and fulfill contracts, as well as commissions receivable related to reinsurance brokerage activity.

New Accounting Pronouncements Recently Adopted

In October 2016, the FASB issued new guidance which changes the evaluation of whether a reporting entity is the primary beneficiary of a variable interest entity by changing how a reporting entity that is a single decision maker of a variable interest entity treats indirect interests in the entity held through related parties that are under common control with the reporting entity. If a reporting entity satisfies the first characteristic of a primary beneficiary (such that it is the single decision maker of a variable interest entity), the new guidance requires that reporting entity, in determining whether it satisfies the second characteristic of a primary beneficiary, to include all of its direct variable interest in a variable interest entity and, on a proportionate basis, its indirect variable interests in a variable interest entity held through related parties, including related parties that are under common control with the reporting entity. The adoption of this guidance did not have a significant impact on its financial position, results of operations and statement of cash flows.

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In April 2016, the FASB issued new guidance which simplifies several aspects of the accounting for employee share-based payment transactions, including the accounting for income taxes, forfeitures and statutory tax withholding requirements, as well as classification in the statement of cash flows. The new guidance requires that companies record all excess tax benefits and tax deficiencies as an income tax benefit or expense in the income statement and classify excess tax benefits as an operating activity in the statement of cash flows. The Company adopted this new guidance prospectively, effective January 1, 2017 and prior periods have not been adjusted. For the six months ended June 30, 2017, the adoption of this new standard reduced income tax expense in the consolidated statement of income by approximately $48 million. For the six months ended June 30, 2016, the Company recorded an excess tax benefit of $24 million as an increase to equity in its consolidated balance sheet, which was reflected as cash provided by financing activities in the consolidated statement of cash flows.

In March 2016, the FASB issued new guidance which eliminates the requirement that when an investment qualifies for use of the equity method as a result of an increase in the level of ownership interest or degree of influence, an investor must adjust the investment, results of operations and retained earnings retroactively on a step-by-step basis as if the equity method had been in effect during all previous periods that the investment had been held. The amendments require that the equity method investor add the cost of acquiring the additional interest in the investee to the current basis of the investor’s previously held interest and adopt the equity method of accounting as of the date the investment becomes qualified for equity method accounting. Therefore, upon qualifying for the equity method of accounting, no retroactive adjustment of the investment is required. The amendments require that an entity that has an available-for-sale equity security that becomes qualified for the equity method of accounting recognize through earnings the unrealized holding gain or loss in accumulated other comprehensive income at the date the investment becomes qualified for use of the equity method. The new guidance is effective for all entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2016. The guidance was adopted on January 1, 2017 and did not have an impact on the Company's financial position or results of operations.

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Item 2.     Management’s Discussion and Analysis of Financial Condition and Results of Operations.

General

Marsh & McLennan Companies, Inc. and its consolidated subsidiaries (the "Company") is a global professional services firm offering clients advice and solutions in risk, strategy and people. It is the parent company of a number of leading risk advisors and specialty consultants, including: Marsh, the insurance broker, intermediary and risk advisor; Guy Carpenter, the risk and reinsurance specialist; Mercer, the provider of HR and Investment related financial advice and services; and Oliver Wyman Group, the management, economic and brand consultancy. With more than 60,000 employees worldwide and annual revenue of more than $13 billion, the Company provides analysis, advice and transactional capabilities to clients in more than 130 countries.

The Company operates through two segments:

• Risk and Insurance Services includes risk management activities (risk advice, risk transfer and risk control and mitigation solutions) as well as insurance and reinsurance broking and services. The Company conducts business in this segment through Marsh and Guy Carpenter.

• Consulting includes wealth, health and career consulting services and products, and specialized management, economic and brand consulting services. The Company conducts business in this segment through Mercer and Oliver Wyman Group.

Effective January 1, 2017, Mercer established a Wealth business reflecting a unified client strategy for its former Retirement and Investments businesses. Wealth is comprised of two practices, Defined Benefit Consulting & Administration (DBA), and Investment Management & Related Services (IMS). DBA encompasses mature businesses primarily in defined benefit and actuarial consulting, along with defined benefit administration. IMS includes businesses primarily in delegated solutions, defined contribution related investment services, and financial wellness. Among the changes, defined benefit investment consulting, previously reported in the Investments business, is now included in Defined Benefit Consulting & Administration. Revenue information is reported for these two practices to provide investors better insight into the underlying growth dynamics within Wealth. This change has no impact on previously reported Mercer total revenue, Consulting segment revenue or operating income, or consolidated revenue or financial results.

A reconciliation of segment operating income to total operating income is included in Note 15 to the consolidated financial statements included in Part I Item 1 in this report. The accounting policies used for each segment are the same as those used for the consolidated financial statements.

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Consolidated Results of Operations

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions, except per share figures)	2017		2016		2017		2016
Revenue	$	3,495	$	3,376	$	6,998	$	6,712
Expense:
Compensation and Benefits	1,935		1,872		3,880		3,726
Other Operating Expenses	796		778		1,545		1,527
Operating Expenses	2,731		2,650		5,425		5,253
Operating Income	764		726		1,573		1,459
Net income before non-controlling interests	507		480		1,085		970
Net Income Attributable to the Company	$	501	$	472	$	1,070	$	953
Net Income Per Share Attributable to the Company:
Basic	$	0.98	$	0.91	$	2.08	$	1.83
Diluted	$	0.96	$	0.90	$	2.05	$	1.81
Average Number of Shares Outstanding:
Basic	514		521		514		521
Diluted	520		525		521		526
Shares Outstanding at June 30	513		519		513		519

The Company's consolidated operating income of $764 million in the second quarter of 2017 increased 5% compared to the prior year. This reflects the impact of a 4% increase in revenue and a 3% increase in expense. Revenue increased 4% in Risk and Insurance Services and 3% in Consulting as compared to the second quarter of last year.

Net income before non-controlling interests increased 6% to $507 million due to the increase in operating income, partially offset by higher interest expense. Diluted net income per share attributable to the Company increased 7% to $0.96, compared to $0.90 last year, reflecting a $29 million increase in net income as well as a 1% decrease in the average number of diluted shares outstanding as compared to the same period last year. The number of shares issued related to the vesting of share awards and exercise of employee stock options was more than offset by shares repurchased over the past four quarters. In addition, in accordance with the change in accounting for stock compensation, the excess tax benefits for unvested shares and unexercised stock options are no longer included in the calculation of common stock equivalents ("CSEs") under the Treasury stock method. This had the effect of increasing CSEs by approximately 1.6 million shares.

Consolidated operating income was approximately $1.6 billion in the first six months of 2017, an increase of 8%

compared with the first six months of 2016, reflecting 4% growth in revenue and 3% growth in expenses.

Net income attributable to the Company increased 12% reflecting the increase in operating income as well as the impact of a credit to income tax expense related to the required change in accounting for share based awards, partially offset by higher interest expense. Diluted net income per share attributable to the Company increased 13% to $2.05 compared to $1.81 in 2016, reflecting a $117 million increase in net income attributable to the Company as well as a 1% decrease in the average number of diluted shares outstanding. The number of shares issued related to the vesting of share awards and exercise of employee stock options was more than offset by shares repurchased over the past four quarters. In addition, in accordance with the change in accounting for stock compensation discussed above, CSEs increased by approximately 1.7 million shares.

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Consolidated Revenue and Expense

Revenue - Components of Change

The Company conducts business in more than 130 countries. As a result, foreign exchange rate movements may impact period-to-period comparisons of revenue. Similarly, certain other items such as the revenue impact of acquisitions and dispositions, including transfers among businesses, may impact period-to-period comparisons of revenue. Underlying revenue measures the change in revenue from one period to another by isolating these impacts. The impact of foreign currency exchange fluctuations, acquisitions and dispositions, including transfers among businesses, on the Company’s operating revenues by segment was as follows:

	Three Months Ended June 30,						% Change GAAP Revenue		Components of Revenue Change*
									Currency Impact		Acquisitions/ Dispositions Impact		Underlying Revenue
(In millions)	2017			2016
Risk and Insurance Services
Marsh	$	1,614		$	1,559		4	%	(1	)%	4	%	2	%
Guy Carpenter	293			285			3	%	(1	)%	—		4	%
Subtotal	1,907			1,844			3	%	(1	)%	3	%	2	%
Fiduciary Interest Income	9			6
Total Risk and Insurance Services	1,916			1,850			4	%	(1	)%	3	%	2	%
Consulting
Mercer	1,109			1,079			3	%	(2	)%	2	%	3	%
Oliver Wyman Group	483			460			5	%	(2	)%	—		7	%
Total Consulting	1,592			1,539			3	%	(2	)%	2	%	4	%
Corporate / Eliminations	(13		)	(13		)
Total Revenue	$	3,495		$	3,376		4	%	(2	)%	2	%	3	%

	Three Months Ended June 30,				% Change GAAP Revenue		Components of Revenue Change*
							Currency Impact		Acquisitions/ Dispositions Impact		Underlying Revenue
(In millions)	2017		2016
Marsh:
EMEA	$	497	$	479	4	%	(4	)%	7	%	—
Asia Pacific	168		183		(8	)%	—		(11	)%	3	%
Latin America	99		93		6	%	(2	)%	3	%	4	%
Total International	764		755		1	%	(3	)%	2	%	1	%
U.S. / Canada	850		804		6	%	—		5	%	2	%
Total Marsh	$	1,614	$	1,559	4	%	(1	)%	4	%	2	%
Mercer:
Defined Benefit Consulting & Administration	$	340	$	371	(8	)%	(4	)%	(1	)%	(3	)%
Investment Management & Related Services	192		153		26	%	(1	)%	15	%	11	%
Total Wealth	532		524		2	%	(3	)%	3	%	1	%
Health	423		410		3	%	(1	)%	1	%	3	%
Career	154		145		6	%	(2	)%	2	%	5	%
Total Mercer	$	1,109	$	1,079	3	%	(2	)%	2	%	3	%

Underlying revenue measures the change in revenue using consistent currency exchange rates, excluding the impact of certain items that affect comparability, such as: acquisitions, dispositions and transfers among businesses and the deconsolidation of Marsh India.
*	Components of revenue change may not add due to rounding.

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	Six Months Ended June 30,						% Change GAAP Revenue		Components of Revenue Change*
									Currency Impact		Acquisitions/ Dispositions Impact		Underlying Revenue
(In millions)	2017			2016
Risk and Insurance Services
Marsh	$	3,210		$	3,047		5	%	(1	)%	4	%	3	%
Guy Carpenter	678			659			3	%	(1	)%	—		4	%
Subtotal	3,888			3,706			5	%	(1	)%	3	%	3	%
Fiduciary Interest Income	17			12
Total Risk and Insurance Services	3,905			3,718			5	%	(1	)%	3	%	3	%
Consulting
Mercer	2,186			2,118			3	%	(2	)%	2	%	3	%
Oliver Wyman Group	932			899			4	%	(2	)%	—		6	%
Total Consulting	3,118			3,017			3	%	(2	)%	2	%	4	%
Corporate / Eliminations	(25		)	(23		)
Total Revenue	$	6,998		$	6,712		4	%	(2	)%	2	%	3	%

	Six Months Ended June 30,				% Change GAAP Revenue		Components of Revenue Change*
							Currency Impact		Acquisitions/ Dispositions Impact		Underlying Revenue
(In millions)	2017		2016
Marsh:
EMEA	$	1,086	$	1,049	4	%	(4	)%	6	%	2	%
Asia Pacific	320		329		(3	)%	—		(10	)%	7	%
Latin America	179		164		9	%	—		4	%	5	%
Total International	1,585		1,542		3	%	(3	)%	2	%	3	%
U.S. / Canada	1,625		1,505		8	%	—		5	%	3	%
Total Marsh	$	3,210	$	3,047	5	%	(1	)%	4	%	3	%
Mercer:
Defined Benefit Consulting & Administration	$	674	$	732	(8	)%	(4	)%	(3	)%	(2	)%
Investment Management & Related Services	378		300		26	%	—		15	%	10	%
Total Wealth	1,052		1,032		2	%	(3	)%	3	%	2	%
Health	838		810		3	%	(1	)%	2	%	3	%
Career	296		276		7	%	(1	)%	3	%	6	%
Total Mercer	$	2,186	$	2,118	3	%	(2	)%	2	%	3	%

Underlying revenue measures the change in revenue using consistent currency exchange rates, excluding the impact of certain items that affect comparability, such as: acquisitions, dispositions and transfers among businesses and the deconsolidation of Marsh India.
*	Components of revenue change may not add due to rounding.

Revenue

Consolidated revenue for the second quarter of 2017 was $3.5 billion, an increase of 4%, or 3% on an underlying basis. An increase of 2% from the impact of acquisitions was offset by a decrease of 2% from the impact of foreign currency translation.

Revenue in the Risk and Insurance Services segment for the second quarter of 2017 was $1.9 billion, an increase of 4% from the same period last year and 2% on an underlying basis. Consulting revenue of $1.6 billion in the second quarter of 2017 increased 3%, or 4% on an underlying basis.

For the first six months of 2017, consolidated revenue increased 4% on a reported basis and 3% on an underlying basis. Risk and Insurance Services revenue increased 5% from the same period in 2016, or 3% on an underlying

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basis. Consulting revenue increased 3% compared with the six-month period last year, or 4% on an underlying basis.

Operating Expense

Consolidated operating expense in the second quarter increased 3% compared with the same period last year, reflecting a 2% increase on an underlying basis and a 3% increase from acquisitions, partly offset by a 2% decrease from the impact of foreign currency translation. The increase in underlying expenses is primarily due to higher base salaries, incentive compensation and severance related costs, partly offset by lower costs related to liabilities for errors and omissions.

Expenses for the six months of 2017 increased 3% compared to the same period in 2016, reflecting a 2% increase

on an underlying basis and a 3% increase from acquisitions, offset by a 2% decrease from the impact of foreign

currency translation. The increase in underlying expenses is due primarily to higher base salaries, incentive compensation and severance related costs, partly offset by decreases in contingent consideration related to acquisitions and lower costs related to liabilities for errors and omissions.

Risk and Insurance Services

The results of operations for the Risk and Insurance Services segment are presented below:

For the Three and Six Months Ended June 30,	Three Months						Six Months
(In millions)	2017			2016			2017			2016
Revenue	$	1,916		$	1,850		$	3,905		$	3,718
Compensation and Benefits	968			934			1,948			1,855
Other Expenses	420			426			816			838
Expense	1,388			1,360			2,764			2,693
Operating Income	$	528		$	490		$	1,141		$	1,025
Operating Income Margin	27.5		%	26.6		%	29.2		%	27.6		%

Revenue

Revenue in the Risk and Insurance Services segment in the second quarter of 2017 was $1.9 billion, an increase of 4% as compared to the same period last year, reflecting a 2% increase in underlying revenue and a 3% increase related to acquisitions, partially offset by a 1% decrease from the impact of foreign currency translation.

In Marsh, revenue in the second quarter of 2017 was $1.6 billion, an increase of 4% compared with the same quarter of the prior year, reflecting an increase in underlying revenue of 2% and a 4% increase from acquisitions, offset by a 1% decrease from the impact of foreign currency translation. Revenue in international operations grew 1% on an underlying basis, with growth of 3% in Asia Pacific and 4% in Latin America, while growth in EMEA was flat. In U.S./Canada, underlying revenue increased 2% compared to prior year. Guy Carpenter's second quarter revenue increased 3%, reflecting an increase of 4% on an underlying basis partly offset by a 1% decrease from the impact of foreign currency translation.

Revenue in the Risk and Insurance Services segment increased 5% in the first six months of 2017 compared with 2016, or 3% on an underlying basis. In Marsh, underlying revenue increased 3% in U.S./Canada. The international division increased 3% on an underlying basis, reflecting a 2% increase in EMEA, a 7% increase in Asia Pacific and a 5% increase in Latin America.

Expense

Expenses in the Risk and Insurance Services segment increased 2% in the second quarter of 2017 compared with the same period last year, reflecting increases of 4% related to acquisitions, partly offset by a 2% decrease from the impact of foreign currency translation. Expenses were flat on an underlying basis as higher base salaries and incentive compensation costs were offset by decreases in contingent consideration related to acquisitions and lower costs related to liabilities for errors and omissions.

Expenses for the six month period of 2017 increased 3% compared to the prior year, reflecting increases of 1% in underlying expenses and 4% related to acquisitions, partly offset by a 2% decrease from the impact of foreign currency translation. The underlying expense increase is primarily due to higher base salaries, incentive compensation and amortization of intangible assets, partly offset by lower contingent consideration related to acquisitions and lower costs related to liabilities for errors and omissions.

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Consulting

The results of operations for the Consulting segment are presented below:

For the Three and Six Months Ended June 30,	Three Months						Six Months
(In millions)	2017			2016			2017			2016
Revenue	$	1,592		$	1,539		$	3,118		$	3,017
Compensation and Benefits	883			852			1,758			1,699
Other Expenses	426			402			836			788
Expense	1,309			1,254			2,594			2,487
Operating Income	$	283		$	285		$	524		$	530
Operating Income Margin	17.8		%	18.5		%	16.8		%	17.6		%

Revenue

Revenue in the Consulting segment in the second quarter of 2017 was $1.6 billion, an increase of 3% compared to the same period last year, reflecting a 4% increase in underlying revenue and a 2% increase related to acquisitions, partially offset by a 2% decrease from the impact of foreign currency translation.

Effective January 1, 2017, Mercer established a Wealth business reflecting a unified client strategy for its former Retirement and Investments businesses.

Mercer's revenue of approximately $1.1 billion increased 3% compared to the prior year on both a reported and underlying basis. On an underlying basis, revenue in Wealth increased 1%, Health increased 3%, and Career increased 5%. Within Wealth, Investment Management & Related Services increased 11% and Defined Benefit Consulting & Administration decreased 3% compared to the same period last year. Oliver Wyman's revenue increased 5% to $483 million in the second quarter of 2017 compared to the same period last year, reflecting a 7% increase on an underlying basis partly offset by a decrease of 2% from the impact of foreign currency translation.

Consulting revenue in the first six months of 2017 increased 3%. Underlying revenue increased 4% with underlying growth of 3% at Mercer and 6% at Oliver Wyman.

Expense

Consulting expenses in the second quarter of 2017 increased 4% as compared to the second quarter of 2016. This reflects an increase of 4% on an underlying basis and a 3% increase from acquisitions, partly offset by a 2% decrease from the impact of foreign currency translation. The underlying expense increase in the second quarter of 2017 was primarily due to higher base salaries, severance costs related to the Mercer business restructuring and higher asset based fees, partly offset by lower costs related to liabilities for errors and omissions.

Underlying expenses for the six months of 2017 increased 3% as compared to 2016, primarily due to higher base salaries, severance costs related to the Mercer business restructuring and higher asset based fees, partly offset by lower costs related to liabilities for errors and omissions.

Corporate and Other

Corporate expenses were $47 million and $49 million for the second quarter of 2017 and 2016, respectively. For the first six months of 2017, corporate expenses were $92 million compared with $96 million for the same period last year. The decrease in expenses is primarily due to lower outside service costs.

Interest

Interest income earned on corporate funds was $2 million in both the second quarter of 2017 and 2016 and $4 million for both of the six month periods of 2017 and 2016. Interest expense increased $12 million in the second quarter of 2017 compared with the second quarter of 2016 and increased $24 million for the six months of 2017 compared with the same period last year. The increase in interest expense is primarily due to higher average debt outstanding in 2017.

Investment Income (Loss)

The caption "Investment income (loss)" in the consolidated statements of income comprises realized and unrealized gains and losses from investments. It includes, when applicable, other-than-temporary declines in the value of debt and available-for-sale securities and equity method gains or losses on its investments in private equity funds. The

37

Company's investments may include direct investments in insurance, consulting or other strategically linked companies and investments in private equity funds. The Company had a net investment income of $5 million in the second quarter of 2017 compared to $1 million for the same period in 2016. For the first six months of 2017, the Company recorded net investment income of $5 million compared to a net investment loss of $2 million for the six months of 2016.

Income Taxes

The Company's effective tax rate in the second quarter of 2017 was 28.6% compared to 29.5% in the second quarter of 2016. The effective tax rate for the first six months of 2017 was 25.9% compared with 29.0% for the first six months of 2016. The rates reflect foreign operations taxed at rates below the U.S. statutory tax rate, including the effect of repatriation, as well as the impact of discrete tax matters such as tax legislation, changes in valuation allowances, nontaxable adjustments to contingent acquisition consideration and, starting in 2017, excess tax benefits related to share-based compensation. Excluding excess tax benefits related to share based payments, the effective tax rate for the first six months of 2017 was 29.1%.

The effective tax rate is sensitive to the geographic mix and repatriation of the Company's earnings, which may result in higher or lower tax rates. U.S. federal and state corporate tax rates substantially exceed tax rates applicable in most jurisdictions outside the U.S. A significant portion of the Company's profits are earned outside the U.S. In 2017, the forecasted pre-tax income in the U.K., Barbados, Canada, Australia and Germany is expected to account for approximately 60% of the Company's total non-U.S. pre-tax income, with estimated effective tax rates in those countries of 23%, 0%, 27%, 30% and 32%, respectively. Consequently, increases in the profitability of the Company's U.S.-based operations relative to non-U.S. operations would tend to result in higher effective tax rates. Losses in one jurisdiction, generally, cannot offset earnings in another, and within certain jurisdictions profits and losses may not offset between entities. Consequently, losses in certain jurisdictions may require valuation allowances affecting the effective tax rate, depending on estimates of the realizability of associated deferred tax assets. The tax rate is also sensitive to changes in unrecognized tax benefits, including the impact of settled tax audits and expired statutes of limitation.

Changes in tax laws or tax rulings may have a significant impact on our effective tax rate. Discussions continue within Congress and the Administration about broad reform of the corporate tax system in the U.S. It is not possible to predict the ultimate outcome of these discussions. Future legislation could have a material impact on our effective tax rate and consolidated financial statements due to reforms that could include changes in the corporate tax rate and in the way U.S. corporations are taxed on foreign earnings.

The Company reports a liability for unrecognized tax benefits resulting from uncertain tax positions taken or expected to be taken in tax returns. The Company's gross unrecognized tax benefits increased from $65 million at December 31, 2016 to $66 million at June 30, 2017. It is reasonably possible that the total amount of unrecognized tax benefits will decrease between zero and approximately $9 million within the next twelve months due to settlements of audits and expirations of statutes of limitation.

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Liquidity and Capital Resources

The Company is organized as a legal entity separate and distinct from its operating subsidiaries. As the Company does not have significant operations of its own, the Company is dependent upon dividends and other payments from its operating subsidiaries to pay principal and interest on its outstanding debt obligations, pay dividends to stockholders, repurchase its shares and pay corporate expenses. The Company also provides financial support to its operating subsidiaries for acquisitions, investments and certain parts of their business that require liquidity, such as the capital markets business of Guy Carpenter. Other sources of liquidity include borrowing facilities discussed below in Financing Cash Flows.

The Company derives a significant portion of its revenue and operating profit from operating subsidiaries located outside of the United States. Funds from those operating subsidiaries are regularly repatriated to the United States out of annual earnings. At December 31, 2016, the Company had approximately $850 million of cash and cash equivalents in its foreign operations, substantially all of which is considered to be permanently invested in those operations to fund foreign investments and working capital needs. The $850 million of non-U.S. cash and cash equivalents considered permanently reinvested includes $157 million of operating funds required to be maintained for regulatory requirements or as collateral under certain captive insurance arrangements. The Company expects to continue its practice of repatriating foreign funds from its non-U.S. operating subsidiaries out of current annual earnings. While management does not foresee a need to repatriate the funds which are currently deemed permanently invested, if facts or circumstances change, management could elect to repatriate them, if necessary, which could result in higher effective tax rates in the future. In the first six months of 2017, the Company recorded foreign currency translation adjustments which increased net equity by approximately $525 million.

Cash and cash equivalents on our consolidated balance sheets includes funds available for general corporate purposes. Funds held on behalf of clients in a fiduciary capacity are segregated and shown separately in the consolidated balance sheets as an offset to fiduciary liabilities. Fiduciary funds cannot be used for general corporate purposes, and should not be considered as a source of liquidity for the Company.

Operating Cash Flows

The Company generated $343 million of cash from operations for the six months ended June 30, 2017, compared to $229 million generated from operations for the same period in 2016. These amounts reflect the net income of the Company during those periods, excluding gains or losses from investments, adjusted for non-cash charges and changes in working capital which relate primarily to the timing of payments of accrued liabilities and pension plan contributions or receipts of assets.

Pension Related Items

Contributions

The Company's policy for funding its tax-qualified defined benefit plans is to contribute amounts at least sufficient to meet the funding requirements set forth in the applicable laws or regulations of the U.S. and other jurisdictions. During the first six months of 2017, the Company contributed $105 million to its non-U.S. defined benefit pension plans and $15 million to its U.S. defined benefit pension plans. In the first six months of 2016, the Company contributed $90 million to its non-U.S. defined benefit pension plans and $13 million to its U.S. defined benefit pension plans.

In the U.S., contributions to the tax-qualified defined benefit plans are based on ERISA guidelines and the Company generally expects to maintain a funded status of 80% or more of the liability determined under the ERISA guidelines.

Outside the U.S., the Company has a large number of defined benefit pension plans, the largest of which are in the U.K., which comprise approximately 81% of non-U.S. plan assets at December 31, 2016. Contribution rates for non-U.S. plans are generally based on local funding practices and statutory requirements, which may differ significantly from measurements under U.S. GAAP. In the U.K., the assumptions used to determine pension contributions are the result of legally-prescribed negotiations between the Company and the plans' trustee that typically occur every three years in conjunction with the actuarial valuation of the plans. Currently, this results in a lower funded status than under U.S. GAAP and may result in contributions irrespective of the U.S. GAAP funded status. In November 2016, the Company and the Trustee of the U.K. Defined Benefits Plans agreed to a funding deficit recovery plan for the U.K. defined benefit pension plans. The current agreement with the Trustee sets out the annual deficit contributions which would be due based on the deficit at December 31, 2015. The funding level is subject to re-assessment, in most cases on November 1 of each year. If the funding level on November 1 is sufficient, no deficit funding contributions will be required in the following year, and the contribution amount will be deferred. As part of a

39

long-term strategy, which depends on having greater influence over asset allocation and overall investment decisions, in November 2016 the Company renewed its agreement to support annual deficit contributions by the U.K. operating companies under certain circumstances, up to GBP 450 million over a seven-year period.

The Company expects to fund an additional $119 million to its non-U.S. defined benefit plans over the remainder of 2017, comprising approximately $55 million to plans outside of the U.K. and $64 million to the U.K. plans. The Company also expects to fund an additional $17 million to its U.S. defined benefit plans during the remainder of 2017.

Funding amounts may be influenced by future asset performance, the level of discount rates and other variables impacting the funded status of the plan.

Changes in Pension Plans

The Company continues to manage the cost and assess the competitiveness of its benefits programs, and also to manage the risks related to its defined benefit pension plan liabilities. In October 2016, the Company modified its U.S. defined benefit pension plans to discontinue further benefit accruals for participants after December 31, 2016. At the same time, the Company amended its U.S. defined contribution retirement plans for most of its U.S. employees to add an automatic Company contribution equal to 4% of eligible base pay beginning on January 1, 2017. This new Company contribution, together with the Company’s current matching contribution, provides eligible U.S. employees with the opportunity to receive a total contribution of up to 7% of eligible base pay. As required under GAAP, the defined benefit plans that were significantly impacted by the modification were re-measured in October 2016 using market data and assumptions as of the modification date. The net periodic pension expense recognized in 2016 reflects the weighted average costs of the December 31, 2015 measurement and the October 2016 re-measurement. In addition, the U.S. qualified plans were merged effective December 30, 2016.

In March 2017, the Company modified its defined benefit pension plans in Canada to discontinue further benefit accruals for participants after December 31, 2017 and replaced them with a defined contribution arrangement. The Company also amended its post-retirement benefits plan in Canada so that individuals who retire after April 1, 2019 will not be eligible to participate, except in certain situations. The Company re-measured the assets and liabilities of the plans, based on assumptions and market conditions on the amendment date.

Financing Cash Flows

Net cash provided by financing activities was $16 million for the six-month period ended June 30, 2017, compared with $376 million net cash used by such activities for the same period in 2016.

Debt

The Company has established a short-term debt financing program of up to $1.5 billion through the issuance of commercial paper. The proceeds from the issuance of commercial paper are used for general corporate purposes. The Company had $150 million of commercial paper outstanding at June 30, 2017 at an effective interest rate of 1.45%.

In January 2017, the Company issued $500 million of 2.75% senior notes due in 2022 and $500 million of 4.35% senior notes due in 2047. The Company used the net proceeds for general corporate purposes, which included the repayment of $250 million of senior notes in April 2017.

In March 2016, the Company issued $350 million of 3.30% seven-year senior notes. The Company used the net proceeds for general corporate purposes.

Credit Facilities

The Company and certain of its subsidiaries maintain a $1.5 billion multi-currency five-year unsecured revolving credit facility. The interest rate on this facility is based on LIBOR plus a fixed margin which varies with the Company's credit ratings. This facility expires in November 2020 and requires the Company to maintain certain coverage and leverage ratios which are tested quarterly. There were no borrowings outstanding under this facility at June 30, 2017.

The Company's senior debt is currently rated A- by Standard & Poor's and Baa1 by Moody's. The Company's short-term debt is currently rated P-2 by Moody's and A-2 by Standard & Poor's. The Company carries a stable outlook from Moody's and Standard & Poor's.

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Share Repurchases

During the first six months of 2017, the Company repurchased 5.4 million shares of its common stock for total consideration of $400 million at an average price per share of $74.03. In November 2016, the Board of Directors authorized an increase in the Company’s share repurchase program, which supersedes any prior authorization, allowing management to buy back up to $2.5 billion of the Company’s common stock going forward. As of June 30, 2017, the Company remained authorized to purchase additional shares of its common stock up to a value of approximately $2.0 billion. There is no time limit on this authorization.

During the first six months of 2016, the Company repurchased approximately 7.0 million shares of its common stock for consideration of $425 million.

Contingent payments related to acquisitions

During the first six months of 2017, the Company paid $65 million of contingent payments related to acquisitions made in prior periods. These payments are split between financing and operating cash flows in the consolidated statements of cash flows. Payments of $60 million related to the contingent consideration liability that was recorded on the date of acquisition are reflected as financing cash flows. Payments related to increases in the contingent consideration liability subsequent to the date of acquisition of $5 million are reflected as operating cash flows. Remaining estimated future contingent consideration payments of $203 million for acquisitions completed in the first six months of 2017 and in prior years are recorded in accounts payable and accrued liabilities or other liabilities in the consolidated balance sheet at June 30, 2017.

The Company paid deferred purchase consideration related to prior years' acquisitions of $37 million in the first six months of 2017. Remaining deferred cash payments of approximately $135 million for acquisitions completed in the first six months of 2017 and in prior years are recorded in accounts payable and accrued liabilities or other liabilities in the consolidated balance sheet at June 30, 2017.

In the first six months of 2016, the Company paid $50 million of contingent payments related to acquisitions made in prior periods. Of this amount, $24 million was reported as financing cash flows and $26 million as operating cash flows.

Dividends

The Company paid dividends on its common shares of $351 million ($0.68 per share) during the first six months of 2017, as compared with $326 million ($0.62 per share) during the first six months of 2016.

Investing Cash Flows

Net cash used for investing activities amounted to $538 million in the first six months of 2017, compared with $190million used during the same period in 2016.

The Company paid $412 million and $77 million, net of cash acquired, for acquisitions it made during the first six months of 2017 and 2016, respectively.

The Company used cash of $144 million to purchase fixed assets and capitalized software in the first six months of 2017, compared with $114 million in the first six months of 2016, primarily related to computer equipment and software purchases, software development costs and the refurbishing and modernizing of office facilities.

The Company has commitments for potential future investments of approximately $64 million in five private equity funds that invest primarily in financial services companies.

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Commitments and Obligations

The Company’s contractual obligations of the types identified in the table below were of the following amounts as of June 30, 2017:

(In millions of dollars)	Payment due by Period
Contractual Obligations	Total		Within 1 Year		1-3 Years		4-5 Years		After 5 Years
Commercial paper	$	150	$	150	$	—	$	—	$	—
Short-term debt	12		12		—		—		—
Long-term debt	5,517		—		1,079		1,029		3,409
Interest on long-term debt	2,040		208		397		345		1,090
Net operating leases	2,010		315		527		406		762
Service agreements	296		175		114		7		—
Other long-term obligations	369		136		178		51		4
Total	$	10,394	$	996	$	2,295	$	1,838	$	5,265

The above does not include unrecognized tax benefits of $66 million, accounted for under ASC Topic No. 740, as the Company is unable to reasonably predict the timing of settlement of these liabilities, other than approximately $5 million that may become payable within one year. The above does not include the indemnified liabilities discussed in Note 14 as the Company is unable to reasonably predict the timing of settlement of those liabilities. The above does not include net pension liabilities for underfunded plans of approximately $1.9 billion because the timing and amount of ultimate payment of such liability is dependent upon future events, including, but not limited to, future returns on plan assets and changes in the discount rate used to measure the liabilities. The Company expects to contribute approximately $17 million and $119 million to its U.S. and non-U.S. pension plans, respectively, in the remainder of 2017.

New Accounting Guidance

Note 16 to the consolidated financial statements in this report contains a discussion of recently issued accounting guidance and their impact or potential future impact on the Company’s financial results, if determinable.

42

Item 3. Quantitative and Qualitative Disclosures About Market Risk.

Market Risk and Credit Risk

Certain of the Company’s revenues, expenses, assets and liabilities are exposed to the impact of interest rate changes and fluctuations in foreign currency exchange rates and equity markets.

The Company had the following investments subject to variable interest rates:

(In millions)	June 30, 2017
Cash and cash equivalents invested in money market funds, certificates of deposit and time deposits	$	966
Fiduciary cash and investments	$	5,039

Based on the above balances, if short-term interest rates increased or decreased by 10%, or 9 basis points, for the remainder of the year, annual interest income, including interest earned on fiduciary funds, would increase or decrease by approximately $2 million.

Changes in interest rates can also affect the discount rate and assumed rate of return on plan assets, two of the assumptions among several others used to measure net periodic pension expense. The assumptions used to measure plan assets and liabilities are typically assessed at the end of each year, and determine the expense for the subsequent year. Assumptions used to determine net periodic expense for 2017 are discussed in Note 8 to the consolidated financial statements included in our most recently filed Annual Report on Form 10-K. For a discussion on pension expense sensitivity to changes in these rates, see the "Management’s Discussion and Analysis of Financial Condition and Results of Operations-Management’s Discussion of Critical Accounting Policies-Retirement Benefits" section of our most recently filed Annual Report on Form 10-K.

In addition to interest rate risk, our cash and cash equivalents and fiduciary fund investments are subject to potential loss of value due to counter-party credit risk. To minimize this risk, the Company and its subsidiaries invest pursuant to a Board-approved investment policy. The policy mandates the preservation of principal and liquidity and requires broad diversification with counter-party limits assigned based primarily on credit rating and type of investment. The Company carefully monitors its cash and fiduciary fund investments and will further restrict the portfolio as appropriate in response to market conditions. The majority of cash and fiduciary fund investments are invested in short-term bank deposits.

Foreign Currency Risk

The translated values of revenue and expense from the Company’s international operations are subject to fluctuations due to changes in currency exchange rates. The non-U.S. based revenue that is exposed to foreign exchange fluctuations is approximately 50% of total revenue. We periodically use forward contracts and options to limit foreign currency exchange rate exposure on net income and cash flows for specific, clearly defined transactions arising in the ordinary course of business. Although the Company has significant revenue generated in foreign locations which is subject to foreign exchange rate fluctuations, in most cases both the foreign currency revenue and expenses are in the functional currency of the foreign location. As such, under normal circumstances, the U.S. dollar translation of both the revenues and expenses, as well as the potentially offsetting movements of various currencies against the U.S. dollar, generally tends to mitigate the impact on net operating income of foreign currency risk. However, there have been periods where the impact was not mitigated due to external market factors and events, such as the decision in the United Kingdom to exit the European Union. Similar macroeconomic events may result in greater foreign exchange rate fluctuations in the future. If foreign exchange rates of major currencies (Euro, Sterling, Australian dollar and Canadian dollar) moved 10% in the same direction against the U.S. dollar compared with the foreign exchange rates in 2016, the Company estimates net operating income would increase or decrease by approximately $53 million. The Company has exposure to approximately 80 foreign currencies overall. If exchange rates at June 30, 2017 hold constant throughout 2017, the Company estimates the year-over-year impact from conversion of foreign currency earnings will reduce full year net operating income by approximately $5 million.

Equity Price Risk

The Company holds investments in both public and private companies as well as private equity funds. Investments of approximately $123 million are classified as available for sale, which includes the Company's investment in Benefitfocus, approximately $21 million are accounted for using the cost method, and $416 million are accounted for using the equity method, including the Company's investment in Alexander Forbes. The investments are subject

43

to risk of decline in market value, which, if determined to be other than temporary, could result in realized impairment losses. The Company periodically reviews the carrying value of such investments to determine if any valuation adjustments are appropriate under the applicable accounting pronouncements.

As of June 30, 2017, the carrying value of the Company’s investment in Alexander Forbes was $275 million. As of June 30, 2017, the market value of the approximately 443 million shares of Alexander Forbes owned by the Company, based on the June 30, 2017 closing share price of 6.95 South African Rand per share, was approximately $237 million. During the first six months of 2017, the shares closed between 5.99 Rand (in late April) and 7.95 Rand (in early January). During the month of June 2017, Alexander Forbes stock price ranged from 6.25 Rand on June 1 to a high of 7.31 Rand on June 23. The Company considered several factors related to its investment in Alexander Forbes, including its financial position, the near- and long-term prospects of Alexander Forbes and the broader South African economy and capital markets, the length of time and extent to which the market value was below cost and the Company’s intent and ability to retain the investment for a sufficient period of time to allow for anticipated recovery in market value. As a result, the Company determined the investment was not impaired.

Other

A number of lawsuits and regulatory proceedings are pending. See Note 14 ("Claims, Lawsuits and Other Contingencies") to the consolidated financial statements in this report.

44

Item 4. Controls & Procedures.

a. Evaluation of Disclosure Controls and Procedures

Based on their evaluation, as of the end of the period covered by this report, the Company’s Chief Executive Officer and Chief Financial Officer have concluded that the Company’s disclosure controls and procedures (as defined in Rules 13a-15(e) or 15d-15(e) under the Securities Exchange Act of 1934) are effective.

b. Changes in Internal Control

There were no changes in the Company’s internal control over financial reporting identified in connection with the evaluation required by Rules 13a-15(d) or 15d-15(d) under the Securities Exchange Act of 1934 that occurred during the Company’s last fiscal quarter that have materially affected, or are reasonably likely to materially affect, the Company’s internal control over financial reporting.

45

PART II. OTHER INFORMATION

Item 1.        Legal Proceedings.

In April 2017, the Financial Conduct Authority in the United Kingdom (the "FCA") commenced a civil competition investigation into the aviation insurance and reinsurance sector. In connection with that investigation, the FCA carried out an on-site inspection at the London office of Marsh Limited, our Marsh and Guy Carpenter operating subsidiary in the United Kingdom. The FCA indicated that it had reasonable grounds for suspecting that Marsh Limited and other participants in the market have been sharing competitively sensitive information within the aviation insurance and reinsurance broking sector.

In July 2017, the Directorate-General for Competition of the European Commission and the Irish Competition and Consumer Protection Commission conducted on-site inspections at the offices of Marsh and other brokers in Dublin in connection with an investigation into potential anti-competitive practices in the commercial motor insurance market in the Republic of Ireland.

We are cooperating fully with these investigations and are conducting our own reviews. As these investigations are at early stages, we are unable to predict their likely timing, outcome or ultimate impact. There can be no assurance that the ultimate resolution of these or any related matters will not have a material adverse effect on our consolidated financial position, results of operations or liquidity.

We and our subsidiaries are also party to a variety of other legal, administrative, regulatory and government proceedings, claims and inquiries arising in the normal course of business. Additional information regarding certain legal proceedings and related matters is set forth in Note 14 to the consolidated financial statements provided in Part I of this report is incorporated herein by reference.

Item 1A.     Risk Factors.

The Company and its subsidiaries face a number of risks and uncertainties. In addition to the other information in this report and our other filings with the SEC, readers should consider carefully the risk factors discussed in "Part I, Item 1A. Risk Factors" in our Annual Report on Form 10-K for the year ended December 31, 2016. If any of the risks described in our Annual Report on Form 10-K or such other risks actually occur, our business, results of operations or financial condition could be materially adversely affected.

Item 2.         Unregistered Sales of Equity Securities and Use of Proceeds.

Issuer Repurchases of Equity Securities

The Company repurchased approximately 2.7 million shares of its common stock for $200 million during the second quarter of 2017. In November 2016, the Board of Directors of the Company authorized the Company to repurchase up to $2.5 billion in shares of the Company's common stock, which superseded any prior authorizations. As of June 30, 2017, the Company remained authorized to repurchase up to approximately $2.0 billion in shares of its common stock. There is no time limit on the authorization.

Period	(a) Total Number of Shares (or Units) Purchased	(b) Average Price Paid per Share (or Unit)		(c) Total Number of Shares (or Units) Purchased as Part of Publicly Announced Plans or Programs	(d) Maximum Number (or Approximate Dollar Value) of Shares (or Units) that May Yet Be Purchased Under the Plans or Programs
April 1-30, 2017	1,025,138	$	73.1608	1,025,138	$	2,165,752,213
May 1-31, 2017	991,059	$	74.3604	991,059	$	2,092,056,664
June 1-30, 2017	654,477	$	78.3901	654,477	$	2,040,752,167
Total	2,670,674	$	74.8875	2,670,674	$	2,040,752,167

46

Item 3.         Defaults Upon Senior Securities.

None.

Item 4.         Mine Safety Disclosure.

Not Applicable.

Item 5.         Other Information.

None.

Item 6.         Exhibits.

See the Exhibit Index immediately following the signature page of this report, which is incorporated herein by reference.

47

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

Date:	July 28, 2017	/s/ Mark C. McGivney
		Mark C. McGivney
		Chief Financial Officer
Date:	July 28, 2017	/s/ Robert J. Rapport
		Robert J. Rapport
		Senior Vice President & Controller
		(Chief Accounting Officer)

48

EXHIBIT INDEX

Exhibit No.	Exhibit Name
12.1	Statement Re: Computation of Ratio of Earnings to Fixed Charges
31.1	Rule 13a-14(a)/15d-14(a) Certification of Chief Executive Officer
31.2	Rule 13a-14(a)/15d-14(a) Certification of Chief Financial Officer
32.1	Section 1350 Certifications
101.INS	XBRL Instance Document
101.SCH	XBRL Taxonomy Extension Schema
101.CAL	XBRL Taxonomy Extension Calculation Linkbase
101.DEF	XBRL Taxonomy Extension Definition Linkbase
101.LAB	XBRL Taxonomy Extension Label Linkbase
101.PRE	XBRL Taxonomy Extension Presentation Linkbase

49

EX-12.1

Exhibit 12.1

Marsh & McLennan Companies, Inc. and Subsidiaries

Ratio of Earnings to Fixed Charges

(In millions, except ratios)

	Six Months Ended June 30, 2017		Years Ended December 31,
	(Unaudited)			2016		2015		2014		2013		2012
Earnings
Income before income taxes	$	1,464		$	2,480	$	2,307	$	2,057	$	1,973	$	1,696
Interest expense	118			189		163		165		167		181
Portion of rents representative of the interest factor	56			122		127		131		134		139
	$	1,638		$	2,791	$	2,597	$	2,353	$	2,274	$	2,016
Fixed Charges
Interest expense	$	118		$	189	$	163	$	165	$	167	$	181
Portion of rents representative of the interest factor	56			122		127		131		134		139
	$	174		$	311	$	290	$	296	$	301	$	320
Ratio of Earnings to Fixed Charges	9.4			9.0		9.0		7.9		7.6		6.3

EX-31.1

Exhibit 31.1

CERTIFICATIONS

I, Daniel S. Glaser, certify that:

1. I have reviewed this quarterly report on Form 10-Q of Marsh & McLennan Companies, Inc. (the “registrant”);

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant's other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c) Evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d) Disclosed in this report any change in the registrant's internal control over financial reporting that occurred during the registrant's most recent fiscal quarter (the registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting; and

5. The registrant's other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

Date:	July 28, 2017	/s/ Daniel S. Glaser
		Daniel S. Glaser
		President and Chief Executive Officer

EX-31.2

Exhibit 31.2

CERTIFICATIONS

I, Mark C. McGivney, certify that:

1. I have reviewed this quarterly report on Form 10-Q of Marsh & McLennan Companies, Inc. (the “registrant”);

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant's other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c) Evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d) Disclosed in this report any change in the registrant's internal control over financial reporting that occurred during the registrant's most recent fiscal quarter (the registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting; and

5. The registrant's other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

Date:	July 28, 2017	/s/ Mark C. McGivney
		Mark C. McGivney
		Chief Financial Officer

EX-32.1

Exhibit 32.1

Certification of Chief Executive Officer and Chief Financial Officer

The certification set forth below is being submitted in connection with the Quarterly Report on Form 10-Q for the fiscal quarter ended June 30, 2017 of Marsh & McLennan Companies, Inc. (the "Report") for the purpose of complying with Rule 13a-14(b) or Rule 15d-14(b) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), and Section 1350 of Chapter 63 of Title 18 of the United States Code.

Daniel S. Glaser, the President and Chief Executive Officer, and Mark C. McGivney, Chief Financial Officer, of Marsh & McLennan Companies, Inc. each certifies that, to the best of his knowledge:

1. the Report fully complies with the requirements of Section 13(a) or 15(d) of the Exchange Act; and

2. the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of Marsh & McLennan Companies, Inc.

Date:	July 28, 2017	/s/ Daniel S. Glaser
		Daniel S. Glaser
		President and Chief Executive Officer

Date:	July 28, 2017	/s/ Mark C. McGivney
		Mark C. McGivney
		Chief Financial Officer

XML

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2017	Jul. 25, 2017
Document And Entity Information [Abstract]
Entity Registrant Name	MARSH & MCLENNAN COMPANIES, INC.
Entity Central Index Key	0000062709
Trading Symbol	MMC
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		512,524,877

XML

Consolidated Statements of Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Revenue	$ 3,495	$ 3,376	$ 6,998	$ 6,712
Expense:
Compensation and benefits	1,935	1,872	3,880	3,726
Other operating expenses	796	778	1,545	1,527
Operating expenses	2,731	2,650	5,425	5,253
Operating income	764	726	1,573	1,459
Interest income	2	2	4	4
Interest expense	(60)	(48)	(118)	(94)
Investment income (loss)	5	1	5	(2)
Income before income taxes	711	681	1,464	1,367
Income tax expense	204	201	379	397
Net income before non-controlling interests	507	480	1,085	970
Less: Net income attributable to non-controlling interests	6	8	15	17
Net income attributable to the Company	$ 501	$ 472	$ 1,070	$ 953
Net Income Per Share Attributable to the Company:
Basic net income per share attributable to the Company (usd per share)	$ 0.98	$ 0.91	$ 2.08	$ 1.83
Diluted net income per share attributable to the Company (usd per share)	$ 0.96	$ 0.90	$ 2.05	$ 1.81
Average number of shares outstanding:
Average number of shares outstanding - Basic	514	521	514	521
Average number of shares outstanding - Diluted	520	525	521	526
Shares outstanding at June 30,	513	519	513	519

XML

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income before non-controlling interests	$ 507	$ 480	$ 1,085	$ 970
Other comprehensive income (loss), before tax:
Foreign currency translation adjustments	290	(334)	525	(321)
Unrealized investment gains	24	0	19	0
(Loss) gain related to pension/post-retirement plans	(5)	163	28	301
Other comprehensive income (loss), before tax	309	(171)	572	(20)
Income tax expense on other comprehensive income	13	33	20	61
Other comprehensive income (loss), net of tax	296	(204)	552	(81)
Comprehensive income	803	276	1,637	889
Less: comprehensive income attributable to non-controlling interest	6	8	15	17
Comprehensive income attributable to the Company	$ 797	$ 268	$ 1,622	$ 872

XML

Consolidated Balance Sheets - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 966	$ 1,026
Receivables
Commissions and fees	3,740	3,370
Advanced premiums and claims	49	83
Other	298	286
Gross receivables	4,087	3,739
Less-allowance for doubtful accounts and cancellations	(103)	(96)
Net receivables	3,984	3,643
Other current assets	232	215
Total current assets	5,182	4,884
Goodwill	8,821	8,369
Other intangible assets	1,233	1,126
Fixed assets (net of accumulated depreciation and amortization of $1,758 at June 30, 2017 and $1,683 at December 31, 2016)	721	725
Pension related assets	981	776
Deferred tax assets	975	1,097
Other assets	1,529	1,213
Total assets	19,442	18,190
Current liabilities:
Short-term debt	162	312
Accounts payable and accrued liabilities	2,027	1,969
Accrued compensation and employee benefits	1,073	1,655
Accrued income taxes	193	146
Dividends payable	194	0
Total current liabilities	3,649	4,082
Fiduciary liabilities	5,039	4,241
Less – cash and investments held in a fiduciary capacity	(5,039)	(4,241)
Net fiduciary assets	0	0
Long-term debt	5,479	4,495
Pension, post-retirement and post-employment benefits	1,986	2,076
Liabilities for errors and omissions	305	308
Other liabilities	949	957
Commitments and contingencies	0	0
Equity:
Preferred stock, $1 par value, authorized 6,000,000 shares, none issued	0	0
Common stock, $1 par value, authorized 1,600,000,000 shares, issued 560,641,640 shares at June 30, 2017 and December 31, 2016	561	561
Additional paid-in capital	763	842
Retained earnings	12,915	12,388
Accumulated other comprehensive loss	(4,541)	(5,093)
Non-controlling interests	81	80
Stockholders' equity before treasury stock	9,779	8,778
Less – treasury shares, at cost, 47,837,649 shares at June 30, 2017 and 46,150,415 shares at December 31, 2016	(2,705)	(2,506)
Total equity	7,074	6,272
Total liabilities and stockholders' equity	$ 19,442	$ 18,190

XML

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Fixed assets, accumulated depreciation and amortization	$ 1,758	$ 1,683
Preferred stock, par value (usd per share)	$ 1	$ 1
Preferred stock, shares authorized	6,000,000	6,000,000
Preferred stock, shares issued	0	0
Common stock, par value (usd per share)	$ 1	$ 1
Common stock, shares authorized	1,600,000,000	1,600,000,000
Common stock, shares issued	560,641,640	560,641,640
Treasury shares, shares	47,837,649	46,150,415

XML

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Operating cash flows:
Net income before non-controlling interests	$ 1,085	$ 970
Adjustments to reconcile net income to cash provided by operations:
Depreciation and amortization of fixed assets and capitalized software	156	154
Amortization of intangible assets	80	67
Adjustments and payments related to contingent consideration liability	(13)	(8)
Gain on deconsolidation of subsidiary	0	(12)
Provision for deferred income taxes	42	48
(Gain) loss on investments	(5)	2
Loss on disposition of assets	9	3
Share-based compensation expense	75	58
Changes in assets and liabilities:
Net receivables	(318)	(280)
Other current assets	(18)	(37)
Other assets	(34)	(1)
Accounts payable and accrued liabilities	52	(24)
Accrued compensation and employee benefits	(579)	(645)
Accrued income taxes	45	35
Contributions to pension and other benefit plans in excess of current year expense/credit	(214)	(139)
Other liabilities	9	(10)
Effect of exchange rate changes	(29)	48
Net cash provided by operations	343	229
Financing cash flows:
Purchase of treasury shares	(400)	(410)
Net increase in commercial paper	100	0
Proceeds from debt	987	347
Repayments of debt	(256)	(6)
Shares withheld for taxes on vested units – treasury shares	(48)	(38)
Issuance of common stock from treasury shares	94	131
Payments of deferred and contingent consideration for acquisitions	(97)	(63)
Distributions of non-controlling interests	(13)	(11)
Dividends paid	(351)	(326)
Net cash provided by (used for) financing activities	16	(376)
Investing cash flows:
Capital expenditures	(144)	(114)
Net sales (purchases) of long-term investments	12	(4)
Proceeds from sales of fixed assets	4	1
Acquisitions	(412)	(77)
Other, net	2	4
Net cash used for investing activities	(538)	(190)
Effect of exchange rate changes on cash and cash equivalents	119	(63)
Decrease in cash and cash equivalents	(60)	(400)
Cash and cash equivalents at beginning of period	1,026	1,374
Cash and cash equivalents at end of period	$ 966	$ 974

XML

Consolidated Statements of Equity (Unaudited) - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Shares	Non-Controlling Interests
Balance, beginning of year at Dec. 31, 2015		$ 561	$ 861	$ 11,302	$ (4,220)	$ (1,991)	$ 89
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Change in accrued stock compensation costs			(10)
Issuance of shares under stock compensation plans and employee stock purchase plans and related tax impact in 2016			(62)			225
Net income	$ 970			953			17
Dividend equivalents declared – (per share amounts: $1.06 in 2017 and $0.96 in 2016)				(4)
Dividends declared – (per share amounts: $1.06 in 2017 and $0.96 in 2016)				(500)
Other comprehensive income, net of tax	(81)				(81)
Purchase of treasury shares						(410)
Deconsolidation of subsidiary							(14)
Distributions and other changes							(11)
Balance, end of period at Jun. 30, 2016	6,705		789	11,751	(4,301)	(2,176)	81
Balance, beginning of year at Dec. 31, 2016	6,272	$ 561	842	12,388	(5,093)	(2,506)	80
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Change in accrued stock compensation costs			(10)
Issuance of shares under stock compensation plans and employee stock purchase plans and related tax impact in 2016			(69)			201
Net income	1,085			1,070			15
Dividend equivalents declared – (per share amounts: $1.06 in 2017 and $0.96 in 2016)				(2)
Dividends declared – (per share amounts: $1.06 in 2017 and $0.96 in 2016)				(541)
Other comprehensive income, net of tax	552				552
Purchase of treasury shares						(400)
Deconsolidation of subsidiary							0
Distributions and other changes							(14)
Balance, end of period at Jun. 30, 2017	$ 7,074		$ 763	$ 12,915	$ (4,541)	$ (2,705)	$ 81

XML

Consolidated Statements of Equity (Unaudited) (Parenthetical) - $ / shares	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Statement of Stockholders' Equity [Abstract]
Dividends declared per share (in dollars per share)	$ 1.06	$ 0.96
Dividend equivalents declared per share (in dollars per share)	$ 1.06	$ 0.96

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Nature of Operations

6 Months Ended

Jun. 30, 2017

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Nature of Operations

Nature of Operations

Marsh & McLennan Companies, Inc. and its consolidated subsidiaries (the "Company"), a global professional services firm, is organized based on the different services that it offers. Under this structure, the Company’s two segments are Risk and Insurance Services and Consulting.

The Risk and Insurance Services segment provides risk management services and insurance broking, reinsurance broking and insurance program management services for businesses, public entities, insurance companies, associations, professional services organizations and private clients. The Company conducts business in this segment through Marsh and Guy Carpenter.

The Company conducts business in its Consulting segment through Mercer and Oliver Wyman Group. Mercer provides consulting expertise, advice, services and solutions in the areas of health, wealth and career. As of June 30, 2017, Mercer had assets under delegated management of $191 billion worldwide. Oliver Wyman Group provides specialized management and economic and brand consulting services.

Acquisitions impacting the Risk and Insurance Services and Consulting segments are discussed in Note 7 to the consolidated financial statements.

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Principles of Consolidation and Other Matters

6 Months Ended

Jun. 30, 2017

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Principles of Consolidation and Other Matters

Principles of Consolidation and Other Matters

The consolidated financial statements included herein have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission. While certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America have been omitted pursuant to such rules and regulations for interim filings, the Company believes that the information and disclosures presented are adequate to make such information and disclosures not misleading. These consolidated financial statements should be read in conjunction with the consolidated financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016 (the "2016 Form 10-K").

The financial information contained herein reflects all normal recurring adjustments which are, in the opinion of management, necessary for a fair presentation of the Company’s consolidated financial statements as of and for the three and six month periods ended June 30, 2017 and 2016.

Cash and Cash Equivalents

Cash and cash equivalents primarily consist of certificates of deposit and time deposits, with original maturities of three months or less, and money market funds. The estimated fair value of the Company's cash and cash equivalents approximates their carrying value. The Company is required to maintain operating funds of approximately$172 million, primarily related to regulatory requirements outside the United States or as collateral under captive insurance arrangements.

Investments

The Company holds investments in certain private equity funds. Investments in private equity funds are accounted for under the equity method of accounting using a consistently applied three-month lag period adjusted for any known significant changes from the lag period to the reporting date of the Company. The underlying private equity funds follow investment company accounting, where investments within the fund are carried at fair value. Investment gains or losses for the Company's proportionate share of the change in fair value of the funds are recorded in earnings. Investments accounted for using the equity method of accounting are included in other assets in the consolidated balance sheets.

The caption "Investment income (loss)" in the consolidated statements of income comprises realized and unrealized gains and losses from investments recognized in earnings. It includes, when applicable, other than temporary declines in the value of debt and available-for-sale securities and equity method gains or losses on the Company's investments in private equity funds. The Company recorded net investment income of $5 million in the second quarter of 2017 compared to $1 million for the same period in 2016, and net investment income of $5 million compared to a net investment loss of $2 million for the six months ended June 30, 2017 and 2016, respectively.

Income Taxes

The Company's effective tax rate in the second quarter of 2017 was 28.6% compared with 29.5% in the second quarter of 2016. The effective tax rate for the first six months of 2017 and 2016 was 25.9% and 29.0%, respectively. The rates reflect foreign operations which are taxed at rates below the U.S. statutory tax rate, including the effect of repatriation, as well as the impact of discrete tax matters such as tax legislation, changes in valuation allowances, nontaxable adjustments to contingent acquisition consideration and, starting in 2017, excess tax benefits related to share-based compensation.

The Company is routinely examined by tax authorities in the jurisdictions in which it has significant operations. The Company regularly considers the likelihood of assessments in each of the taxing jurisdictions resulting from examinations. When evaluating the potential imposition of penalties, the Company considers a number of relevant factors under penalty statutes, including appropriate disclosure of the tax return position, the existence of legal authority supporting the Company's position, and reliance on the opinion of professional tax advisors.

The Company reports a liability for unrecognized tax benefits resulting from uncertain tax positions taken or expected to be taken in tax returns. The Company's gross unrecognized tax benefits increased from $65 million at December 31, 2016 to $66 million at June 30, 2017. It is reasonably possible that the total amount of unrecognized tax benefits will decrease between zero and approximately $9 million within the next twelve months due to settlements of audits and expirations of statutes of limitation.

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Fiduciary Assets and Liabilities

6 Months Ended

Jun. 30, 2017

Fiduciary Assets And Liabilities [Abstract]

Fiduciary Assets and Liabilities

Fiduciary Assets and Liabilities

In its capacity as an insurance broker or agent, the Company collects premiums from insureds and, after deducting its commissions, remits the premiums to the respective insurance underwriters. The Company also collects claims or refunds from underwriters on behalf of insureds. Unremitted insurance premiums and claims proceeds are held by the Company in a fiduciary capacity. Risk and Insurance Services revenue includes interest on fiduciary funds of $9 million and $6 million for the three months ended June 30, 2017 and 2016, respectively, and $17 million and $12 million for the six months ended June 30, 2017 and 2016, respectively. The Consulting segment recorded fiduciary interest income of less than $1 million for each of the three month periods ended June 30, 2017 and 2016, and $1 million for each of the six months ended June 30, 2017 and 2016. Since fiduciary assets are not available for corporate use, they are shown in the consolidated balance sheets as an offset to fiduciary liabilities.

Net uncollected premiums and claims and the related payables amounted to $7.7 billion at June 30, 2017 and $7.0 billion atDecember 31, 2016. The Company is not a principal to the contracts under which the right to receive premiums or the right to receive reimbursement of insured losses arises. Accordingly, net uncollected premiums and claims and the related payables are not assets and liabilities of the Company and are not included in the accompanying consolidated balance sheets.

In certain instances, the Company advances premiums, refunds or claims to insurance underwriters or insureds prior to collection. These advances are made from corporate funds and are reflected in the accompanying consolidated balance sheets as receivables.

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Per Share Data

6 Months Ended

Jun. 30, 2017

Earnings Per Share [Abstract]

Per Share Data

Per Share Data

Basic net income per share attributable to the Company is calculated by dividing the after-tax income attributable to the Company by the weighted average number of outstanding shares of the Company’s common stock.

Diluted net income per share attributable to the Company is calculated by dividing the after-tax income attributable to the Company by the weighted average number of outstanding shares of the Company’s common stock, which have been adjusted for the dilutive effect of potentially issuable common shares.

Basic and Diluted EPS Calculation	Three Months Ended June 30,				Six Months Ended June 30,
(In millions, except per share amounts)	2017		2016		2017		2016
Basic weighted average common shares outstanding	514		521		514		521
Dilutive effect of potentially issuable common shares	6		4		7		5
Diluted weighted average common shares outstanding	520		525		521		526
Average stock price used to calculate common stock equivalents	$	75.41	$	64.17	$	73.36	$	60.01

There were 12.4 million and 13.9 million stock options outstanding as of June 30, 2017 and 2016, respectively.

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Supplemental Disclosures to the Consolidated Statements of Cash Flows

6 Months Ended

Jun. 30, 2017

Supplemental Cash Flow Information [Abstract]

Supplemental Disclosures to the Consolidated Statements of Cash Flows

Supplemental Disclosures to the Consolidated Statements of Cash Flows

The following schedule provides additional information concerning acquisitions, interest and income taxes paid for the six-month periods ended June 30, 2017 and 2016.

(In millions)	2017			2016
Assets acquired, excluding cash	$	576		$	107
Liabilities assumed	(74		)	(4		)
Contingent/deferred purchase consideration	(90		)	(26		)
Net cash outflow for acquisitions	$	412		$	77

(In millions)	2017		2016
Interest paid	$	92	$	86
Income taxes paid, net of refunds	$	297	$	303

The classification of contingent consideration in the statement of cash flows is determined by whether the payment was part of the initial liability established on the acquisition date (financing) or an adjustment to the acquisition date liability (operating).

The following amounts are included in the consolidated statements of cash flows as a financing activity. The Company paid deferred and contingent consideration of $97 million for the six months ended June 30, 2017. This consisted of deferred purchase consideration related to prior years' acquisitions of $37 million and contingent consideration of $60 million. For the six months ended June 30, 2016, the Company paid deferred and contingent consideration of $63 million, consisting of deferred purchase consideration related to prior years' acquisitions of $39 million and contingent consideration of $24 million.

The following amounts are included in the operating section of the consolidated statements of cash flows. For the six months ended June 30, 2017, the Company recorded a net credit for adjustments to acquisition related accounts of $8 million and contingent consideration payments of $5 million. For the six months ended June 30, 2016, the Company recorded a net charge for adjustments related to acquisition related accounts of $18 million and contingent consideration payments of $26 million.

The Company had non-cash issuances of common stock under its share-based payment plan of $87 million and $70 million for the six months ended June 30, 2017 and 2016, respectively. The Company recorded stock-based compensation expense for equity awards related to restricted stock units, performance stock units and stock options of $75 million and $58 million for the six-month periods ended June 30, 2017 and 2016, respectively.

Effective January 1, 2017, the Company adopted new accounting guidance related to share-based compensation, that requires companies to record excess tax benefits and tax deficiencies as an income tax benefit or expense in the income statement and classify excess tax benefits as an operating activity in the statement of cash flows. Prior to the adoption of this standard, the Company recorded excess tax benefits in equity in the consolidated balance sheet and as a financing activity in the consolidated statement of cash flows. For the six months ended June 30, 2017, the adoption of this new standard reduced income tax expense in the consolidated statement of income by approximately $48 million. For the six months ended June 30, 2016, the Company recorded an excess tax benefit of $24 million as an increase to equity in its consolidated balance sheet, which was reflected as cash provided by financing activities in the consolidated statement of cash flows.

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Other Comprehensive Income (Loss)

6 Months Ended

Jun. 30, 2017

Equity [Abstract]

Other Comprehensive Income (Loss)

Other Comprehensive Income (Loss)

The changes, net of tax, in the balances of each component of Accumulated Other Comprehensive Income ("AOCI") for the three and six-month periods ended June 30, 2017 and 2016, including amounts reclassified out of AOCI, are as follows:

(In millions)	Unrealized Investment Gains		Pension/Post-Retirement Plans Gains (Losses)			Foreign Currency Translation Gains (Losses)			Total Gains (Losses)
Balance as of April 1, 2017	$	16	$	(3,208	)	$	(1,645	)	$	(4,837	)
Other comprehensive income (loss) before reclassifications	14		(40		)	289			263
Amounts reclassified from accumulated other comprehensive income	—		33			—			33
Net current period other comprehensive income (loss)	14		(7		)	289			296
Balance as of June 30, 2017	$	30	$	(3,215	)	$	(1,356	)	$	(4,541	)

(In millions)	Unrealized Investment Gains		Pension/Post-Retirement Plans Gains (Losses)			Foreign Currency Translation Gains (Losses)			Total Gains (Losses)
Balance as of April 1, 2016	$	6	$	(3,014	)	$	(1,089	)	$	(4,097	)
Other comprehensive income (loss) before reclassifications	—		98			(333		)	(235		)
Amounts reclassified from accumulated other comprehensive income	—		31			—			31
Net current period other comprehensive income (loss)	—		129			(333		)	(204		)
Balance as of June 30, 2016	$	6	$	(2,885	)	$	(1,422	)	$	(4,301	)

(In millions)	Unrealized Investment Gains		Pension/Post-Retirement Plans Gains (Losses)			Foreign Currency Translation Gains (Losses)			Total Gains (Losses)
Balance as of January 1, 2017	$	19	$	(3,232	)	$	(1,880	)	$	(5,093	)
Other comprehensive income (loss) before reclassifications	11		(46		)	524			489
Amounts reclassified from accumulated other comprehensive income	—		63			—			63
Net current period other comprehensive income (loss)	11		17			524			552
Balance as of June 30, 2017	$	30	$	(3,215	)	$	(1,356	)	$	(4,541	)

(In millions)	Unrealized Investment Gains		Pension/Post-Retirement Plans Gains (Losses)			Foreign Currency Translation Gains (Losses)			Total Gains (Losses)
Balance as of January 1, 2016	$	6	$	(3,124	)	$	(1,102	)	$	(4,220	)
Other comprehensive income (loss) before reclassifications	—		178			(320		)	(142		)
Amounts reclassified from accumulated other comprehensive income	—		61			—			61
Net current period other comprehensive income (loss)	—		239			(320		)	(81		)
Balance as of June 30, 2016	$	6	$	(2,885	)	$	(1,422	)	$	(4,301	)

The components of other comprehensive income (loss) for the three and six-month periods ended June 30, 2017 and 2016 are as follows:

Three Months Ended June 30,	2017									2016
(In millions)	Pre-Tax			Tax (Credit)			Net of Tax			Pre-Tax			Tax (Credit)			Net of Tax
Foreign currency translation adjustments	$	290		$	1		$	289		$	(334	)	$	(1	)	$	(333	)
Unrealized investment gains	24			10			14			—			—			—
Pension/post-retirement plans:
Amortization of losses included in net periodic pension cost:
Net actuarial losses (a)	42			9			33			43			12			31
Subtotal	42			9			33			43			12			31
Effect of remeasurement	—			1			(1		)	—			—			—
Effect of curtailment	—			—			—			3			1			2
Foreign currency translation (losses) gains	(47		)	(8		)	(39		)	116			21			95
Other	—			—			—			1			—			1
Pension/post-retirement plans gains (losses)	(5		)	2			(7		)	163			34			129
Other comprehensive income (loss)	$	309		$	13		$	296		$	(171	)	$	33		$	(204	)
(a) Components of net periodic pension cost are included in compensation and benefits in the consolidated statements of income. Income tax credits on prior service losses and net actuarial losses are included in income tax expense.

Six Months Ended June 30,	2017									2016
(In millions)	Pre-Tax			Tax (Credit)			Net of Tax			Pre-Tax			Tax (Credit)			Net of Tax
Foreign currency translation adjustments	$	525		$	1		$	524		$	(321	)	$	(1	)	$	(320	)
Unrealized investment gains	19			8			11			—			—			—
Pension/post-retirement plans:
Amortization of losses included in net periodic pension cost:
Prior service cost (a)	—			—			—			1			—			1
Net actuarial losses (a)	82			19			63			84			24			60
Subtotal	82			19			63			85			24			61
Effect of remeasurement	9			3			6			(1		)	—			(1		)
Effect of curtailment	(1		)	—			(1		)	3			1			2
Effect of settlement	1			—			1			1			—			1
Foreign currency translation (losses) gains	(62		)	(11		)	(51		)	213			37			176
Other	(1		)	—			(1		)	—			—			—
Pension/post-retirement plans gains	28			11			17			301			62			239
Other comprehensive income (loss)	$	572		$	20		$	552		$	(20	)	$	61		$	(81	)
(a) Components of net periodic pension cost are included in compensation and benefits in the consolidated statements of income. Tax on prior service gains and net actuarial losses is included in income tax expense.

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Acquisitions

6 Months Ended

Jun. 30, 2017

Business Combinations [Abstract]

Acquisitions

Acquisitions

The Company’s acquisitions have been accounted for as business combinations. Net assets and results of operations are included in the Company’s consolidated financial statements commencing at the respective purchase closing dates. In connection with acquisitions, the Company records the estimated value of the net tangible assets purchased and the value of the identifiable intangible assets purchased, which typically consist of purchased customer lists, developed technology, trademarks and non-compete agreements. The valuation of purchased intangible assets involves significant estimates and assumptions. Until final valuations are complete, any change in assumptions could affect the carrying value of tangible assets, goodwill and identifiable intangible assets.

The Risk and Insurance Services segment completed five acquisitions during the first six months of 2017.

• January – Marsh & McLennan Agency ("MMA") acquired J. Smith Lanier & Co. ("JSL"), a privately held insurance brokerage firm providing insurance, risk management, and employee benefits solutions to businesses and individuals throughout the U.S.

• February – MMA acquired iaConsulting Services, a Texas-based employee benefits consulting firm.

• March – MMA acquired Blakestad, Inc., a Minnesota-based private client and commercial lines insurance agency, and RJF Financial Services, a Minnesota-based retirement advisory firm.

• May – MMA acquired Insurance Partners of Texas, a Texas-based employee benefits consulting firm.

Total purchase consideration for acquisitions made during the six months ended June 30, 2017 was $510 million, which consisted of cash paid of $420 million and deferred purchase and estimated contingent consideration of $90 million. Contingent consideration arrangements are based primarily on earnings before interest, tax, depreciation and amortization ("EBITDA") or revenue targets over a period of two to four years. The fair value of the contingent consideration was based on projected revenue or EBITDA of the acquired entities. Estimated fair values of assets acquired and liabilities assumed are subject to adjustment when purchase accounting is finalized. The Company also paid $37 million of deferred purchase consideration and $65 million of contingent consideration related to acquisitions made in prior years.

The following table presents the preliminary allocation of the acquisition cost to the assets acquired and liabilities assumed during 2017 based on their fair values:

For the Six Months Ended June 30, 2017
(In millions)
Cash	$	420
Estimated fair value of deferred/contingent consideration	90
Total Consideration	$	510
Allocation of purchase price:
Cash and cash equivalents	$	8
Accounts receivable, net	7
Property, plant, and equipment	3
Other intangible assets	196
Goodwill	370
Total assets acquired	584
Current liabilities	4
Other liabilities	70
Total liabilities assumed	74
Net assets acquired	$	510

The following chart provides information about other intangible assets acquired during 2017:

	Amount		Weighted Average Amortization Period
Client relationships	$	184	13 years
Other	12		4 years
	$	196

Prior-Year Acquisitions

The Risk and Insurance Services segment completed nine acquisitions during 2016.

• February – MMA acquired The Celedinas Agency, Inc., a Florida-based brokerage firm, providing property, casualty and marine insurance, as well as employee benefits services, and Aviation Solutions, LLC, a Missouri-based aviation risk advisor and insurance broker.

• March – MMA acquired Corporate Consulting Services, Ltd., a New York-based insurance brokerage and human resource consulting firm.

• August – MMA acquired Benefits Advisory Group LLC, an Atlanta-based employee benefits consulting firm.

• September – MMA acquired Vero Insurance, Inc., a Florida-based agency specializing in private client insurance services.

• November – MMA acquired Benefits Resource Group Agency, LLC, an Ohio-based benefits consulting firm and Presidio Benefits Group, Inc., a California-based employee benefits consulting firm.

• December – Marsh acquired AD Corretora, a multi-line broker located in Brazil, and Bluefin Insurance Group, Ltd, a U.K.-based insurance brokerage.

The Consulting segment completed six acquisitions during 2016.

• January – Mercer acquired The Positive Ageing Company Limited, a U.K.-based firm providing advice on issues surrounding the aging workforce.

• April – Mercer acquired the Extratextual software system and related client contracts. Extratextual is a web based compliance system that assists clients to manage and meet their compliance and risk management obligations.

• December – Oliver Wyman acquired LShift Limited, a software development company, and Mercer acquired Sirota Consulting LLC, a global provider of employee benefit solutions; Pillar Administration, a superannuation provider located in Australia; and Thomsons Online Benefits, a U.K.-based global benefits software business.

Total purchase consideration for acquisitions made during the first six months of 2016 was $105 million, which consisted of cash paid of $79 million and deferred purchase and estimated contingent consideration of $26 million. Contingent consideration arrangements are primarily based on EBITDA or revenue targets over a period of two to four years. The fair value of the contingent consideration was based on projected revenue or earnings of the acquired entities. Estimated fair values of assets acquired and liabilities assumed are subject to adjustment when purchase accounting is finalized. In the first six months of 2016, the Company also paid $39 million of deferred purchase consideration and $50 million of contingent consideration related to acquisitions made in prior years.

Pro-Forma Information

The following unaudited pro-forma financial data gives effect to the acquisitions made by the Company during 2017 and 2016. In accordance with accounting guidance related to pro-forma disclosures, the information presented for current year acquisitions is as if they occurred on January 1, 2016 and reflects acquisitions made in 2016 as if they occurred on January 1, 2015. The unaudited pro-forma information adjusts for the effects of amortization of acquired intangibles. The unaudited pro-forma financial data is presented for illustrative purposes only and is not necessarily indicative of the operating results that would have been achieved if such acquisitions had occurred on the dates indicated, nor is it necessarily indicative of future consolidated results.

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions, except per share figures)	2017		2016		2017		2016
Revenue	$	3,496	$	3,493	$	7,011	$	6,951
Net income attributable to the Company	$	502	$	470	$	1,072	$	950
Basic net income per share attributable to the Company	$	0.98	$	0.90	$	2.08	$	1.82
Diluted net income per share attributable to the Company	$	0.96	$	0.89	$	2.06	$	1.81

The consolidated statements of income include the results of operations of acquired companies since their respective acquisition dates. The consolidated statements of income for the three and six-month periods ended June 30, 2017 include approximately $34 million and$63 million of revenue, respectively, and $5 million and $15 million of operating income, respectively, related to acquisitions made in 2017.

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Goodwill and Other Intangibles

6 Months Ended

Jun. 30, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Other Intangibles

Goodwill and Other Intangibles

The Company is required to assess goodwill and any indefinite-lived intangible assets for impairment annually, or more frequently if circumstances indicate impairment may have occurred. The Company performs the annual impairment assessment for each of its reporting units during the third quarter of each year. In accordance with applicable accounting guidance, the Company assesses qualitative factors to determine whether it is necessary to perform the two-step goodwill impairment test. The Company considers numerous factors, which include whether the fair value of each reporting unit exceeded its carrying value by a substantial margin in its most recent estimate of reporting unit fair values, whether significant acquisitions or dispositions occurred which might alter the fair value of its reporting units, macroeconomic conditions and their potential impact on reporting unit fair values, actual performance compared with budget and prior projections used in its estimation of reporting unit fair values, industry and market conditions, and the year-over-year change in the Company’s share price. The Company completed its qualitative assessment in the third quarter of 2016 and concluded that a two-step goodwill impairment test was not required in 2016 and that goodwill was not impaired.

Changes in the carrying amount of goodwill are as follows:

June 30,
(In millions)	2017		2016
Balance as of January 1, as reported	$	8,369	$	7,889
Goodwill acquired	370		62
Other adjustments(a)	82		(6		)
Balance at June 30,	$	8,821	$	7,945

^(a)  The increase in 2017 primarily reflects the impact of foreign exchange.

Goodwill allocable to the Company’s reportable segments at June 30, 2017 is as follows: Risk and Insurance Services, $6.3 billion and Consulting, $2.5 billion.

Other intangible assets that are not deemed to have an indefinite life are amortized over their estimated lives and reviewed for impairment upon the occurrence of certain triggering events in accordance with applicable accounting literature.

The gross cost and accumulated amortization at June 30, 2017 and December 31, 2016 are as follows:

	June 30, 2017						December 31, 2016
(In millions)	Gross Cost		Accumulated Amortization		Net Carrying Amount		Gross Cost		Accumulated Amortization		Net Carrying Amount
Client Relationships	$	1,581	$	453	$	1,128	$	1,390	$	392	$	998
Other (a)	198		93		105		204		76		128
Amortized intangibles	$	1,779	$	546	$	1,233	$	1,594	$	468	$	1,126

^(a) Primarily non-compete agreements, trade names and developed technology.

Aggregate amortization expense for the six months ended June 30, 2017 and2016 was $80 million and $67 million, respectively. The estimated future aggregate amortization expense is as follows:

For the Years Ending December 31,
(In millions)	Estimated Expense
2017 (excludes amortization through June 30, 2017)	$	85
2018	158
2019	149
2020	127
2021	118
Subsequent years	596
	$	1,233

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Fair Value Measurements

6 Months Ended

Jun. 30, 2017

Fair Value Disclosures [Abstract]

Fair Value Measurements

Fair Value Measurements

Fair Value Hierarchy

The Company has categorized its assets and liabilities that are valued at fair value on a recurring basis into a three-level fair value hierarchy as defined by the Financial Accounting Standards Board ("FASB"). The fair value hierarchy gives the highest priority to quoted prices in active markets for identical assets and liabilities (Level 1) and lowest priority to unobservable inputs (Level 3). In some cases, the inputs used to measure fair value might fall into different levels of the fair value hierarchy. In such cases, the level in the fair value hierarchy, for disclosure purposes, is determined based on the lowest level input that is significant to the fair value measurement. Assets and liabilities recorded in the consolidated balance sheets at fair value are categorized based on the inputs in the valuation techniques as follows:

Level 1. Assets and liabilities whose values are based on unadjusted quoted prices for identical assets or liabilities in an active market (examples include active exchange-traded equity securities and exchange-traded money market mutual funds).

Assets and liabilities measured using Level 1 inputs include exchange-traded equity securities, exchange-traded mutual funds and money market funds.

Level 2. Assets and liabilities whose values are based on the following:

a) Quoted prices for similar assets or liabilities in active markets;

b) Quoted prices for identical or similar assets or liabilities in non-active markets (examples include corporate and municipal bonds, which trade infrequently);

c) Pricing models whose inputs are observable for substantially the full term of the asset or liability (examples include most over-the-counter derivatives, including interest rate and currency swaps); and

d) Pricing models whose inputs are derived principally from or corroborated by observable market data through correlation or other means for substantially the full asset or liability (for example, certain mortgage loans).

The Company does not have any assets or liabilities that are measured using Level 2 inputs.

Level 3. Assets and liabilities whose values are based on prices, or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement. These inputs reflect management’s own assumptions about the assumptions a market participant would use in pricing the asset or liability.

Liabilities measured using Level 3 inputs include liabilities for contingent purchase consideration.

Valuation Techniques

Equity Securities, Money Market Funds and Mutual Funds – Level 1

Investments for which market quotations are readily available are valued at the sale price on their principal exchange or, for certain markets, official closing bid price. Money market funds are valued using a valuation technique that results in price per share at $1.00.

Contingent Purchase Consideration Liability – Level 3

Purchase consideration for some acquisitions made by the Company includes contingent consideration arrangements. These arrangements typically provide for the payment of additional consideration if earnings or revenue targets are met over periods from two to four years. The fair value of the contingent purchase consideration liability is estimated as the present value of future cash flows to be paid, based on projections of revenue and earnings and related targets of the acquired entities.

The following fair value hierarchy table presents information about the Company’s assets and liabilities measured at fair value on a recurring basis as of June 30, 2017 and December 31, 2016.

	Identical Assets (Level 1)				Observable Inputs (Level 2)				Unobservable Inputs (Level 3)				Total
(In millions)	06/30/17		12/31/16		06/30/17		12/31/16		06/30/17		12/31/16		06/30/17		12/31/16
Assets:
Financial instruments owned:
Exchange traded equity securities(a)	$	107	$	89	$	—	$	—	$	—	$	—	$	107	$	89
Mutual funds(a)	140		141		—		—		—		—		140		141
Money market funds(b)	36		22		—		—		—		—		36		22
Total assets measured at fair value	$	283	$	252	$	—	$	—	$	—	$	—	$	283	$	252
Fiduciary Assets:
Money market funds	$	82	$	90	$	—	$	—	$	—	$	—	$	82	$	90
Total fiduciary assets measured at fair value	$	82	$	90	$	—	$	—	$	—	$	—	$	82	$	90
Liabilities:
Contingent purchase consideration liability(c)	$	—	$	—	$	—	$	—	$	203	$	241	$	203	$	241
Total liabilities measured at fair value	$	—	$	—	$	—	$	—	$	203	$	241	$	203	$	241

^(a)  Included in other assets in the consolidated balance sheets.

^(b)  Included in cash and cash equivalents in the consolidated balance sheets.

^(c)  Included in accounts payable and accrued liabilities and other liabilities in the consolidated balance sheets.

During the six-month period ended June 30, 2017, there were no assets or liabilities that were transferred between any of the levels.

The table below sets forth a summary of the changes in fair value of the Company’s Level 3 liabilities as of June 30, 2017 and 2016 that represent contingent consideration related to acquisitions:

(In millions)	2017			2016
Balance at January 1,	$	241		$	309
Additions	34			8
Payments	(65		)	(50		)
Revaluation Impact	(8		)	18
Other (a)	1			(6		)
Balance at June 30,	$	203		$	279

^(a) Primarily reflects the impact of foreign exchange.

The fair value of the contingent purchase consideration liability is based on projections of revenue and EBITDA for the acquired entities in relation to the established targets and are reassessed on a quarterly basis. As set forth in the table above, based on the Company's ongoing assessment of the fair value of contingent consideration, the Company recorded a net decrease in the estimated fair value of such liabilities for prior-period acquisitions of $8 million in the six-month period ended June 30, 2017. A 5% increase in the above mentioned projections would increase the liability by approximately $19 million. A 5% decrease in the above mentioned projections would decrease the liability by approximately $22 million.

Long-Term Investments

The Company holds investments in certain private equity investments, public companies and private companies that are accounted for using the equity method of accounting. The carrying value of these investments was $416 million and $389 million at June 30, 2017 and December 31, 2016, respectively.

Private Equity Investments

The Company's investments in private equity investments were $76 million and $79 million at June 30, 2017 and December 31, 2016, respectively. The carrying values of these private equity investments approximate fair value. The underlying private equity funds follow investment company accounting, where investments within the fund are carried at fair value. The Company records in earnings, investment gains/losses for its proportionate share of the change in fair value of the funds. These investments are included in other assets in the consolidated balance sheets.

Investments in Public and Private Companies

Alexander Forbes: The Company owns approximately 33% of the common stock of Alexander Forbes, a South African company listed on the Johannesburg Stock Exchange, which it purchased in 2014 for 7.50 South African Rand per share. As of June 30, 2017, the carrying value of the Company’s investment in Alexander Forbes was approximately $275 million. As of June 30, 2017, the market value of the approximately 443 million shares of Alexander Forbes owned by the Company, based on the June 30, 2017 closing share price of 6.95 South African Rand per share, was approximately $237 million. During the first six months of 2017, the daily closing share price ranged between 5.99 Rand (in late April) and 7.95 Rand (in early January). During the month of June 2017, Alexander Forbes stock price ranged from 6.25 Rand on June 1 to a high of 7.31 Rand on June 23. The Company considered several factors related to its investment in Alexander Forbes, including its financial position, the near- and long-term prospects of Alexander Forbes and the broader South African economy and capital markets, the length of time and extent to which the market value was below cost and the Company’s intent and ability to retain the investment for a sufficient period of time to allow for anticipated recovery in market value. As a result, the Company determined the investment was not impaired.

The Company’s investment in Alexander Forbes and its other equity investments in private insurance and consulting companies are accounted for using the equity method of accounting, the results of which are included in revenue in the consolidated statements of income and the carrying value of which is included in other assets in the consolidated balance sheets. The Company records its share of income or loss on its equity method investments on a one quarter lag basis.

Benefitfocus: On February 24, 2015, the Company purchased shares of common stock of Benefitfocus (NASDAQ:BNFT) constituting 9.9% of BNFT's outstanding capital stock as of the acquisition date. The purchase price for the BNFT shares and certain other rights and other consideration was approximately $75 million. Until December 31, 2016, the Company accounted for this investment under the cost method of accounting as the shares purchased were categorized as restricted. Effective December 31, 2016, these shares were no longer considered restricted for the purpose of determining if they are marketable securities under applicable accounting guidance, and are now accounted for as available for sale securities and included in other assets in the consolidated balance sheets. The value of the BNFT shares based on the closing price on the NASDAQ as of June 30, 2017 was approximately $102 million. During the first six months of 2017 an unrealized gain related to these shares of approximately $19 million was recorded in other comprehensive income.

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Retirement Benefits

6 Months Ended

Jun. 30, 2017

Defined Benefit Plan [Abstract]

Retirement Benefits

Retirement Benefits

The Company maintains qualified and non-qualified defined benefit pension plans for some of its U.S. and non-U.S. eligible employees. The Company’s policy for funding its tax-qualified defined benefit pension plans is to contribute amounts at least sufficient to meet the funding requirements set forth by U.S. law and the laws of the non-U.S. jurisdictions in which the Company offers such plans.

The target asset allocation for the Company's U.S. Plan was 64% equities and equity alternatives and 36% fixed income and at June 30, 2017, the actual allocation for the Company's U.S. Plan was 64% equities and equity alternatives and 36% fixed income. The target asset allocation for the Company's U.K. Plans, which comprise approximately 81% of non-U.S. plan assets at December 31, 2016, was46% equities and equity alternatives and 54% fixed income. At June 30, 2017, the actual allocation for the U.K. Plans was 46% equities and equity alternatives and 54% fixed income. The assets of the Company's defined benefit plans are diversified and are managed in accordance with applicable laws and with the goal of maximizing the plans' real return within acceptable risk parameters. The Company generally uses threshold-based portfolio re-balancing to ensure the actual portfolio remains consistent with target asset allocation ranges.

The components of the net periodic benefit cost for defined benefit and other post-retirement plans are as follows:

Combined U.S. and significant non-U.S. plans	Pension Benefits						Post-retirement Benefits
For the Three Months Ended June 30,
(In millions)	2017			2016			2017			2016
Service cost	$	19		$	46		$	—		$	—
Interest cost	124			138			1			1
Expected return on plan assets	(230		)	(242		)	—			—
Amortization of prior service cost (credit)	(1		)	(1		)	—			1
Recognized actuarial loss	43			42			—			—
Net periodic benefit (credit) cost	$	(45	)	$	(17	)	$	1		$	2
Curtailment gain	—			(5		)	—			—
Settlement loss	—			1			—			—
Total (credit) cost	$	(45	)	$	(21	)	$	1		$	2
Combined U.S. and significant non-U.S. plans	Pension Benefits						Post-retirement Benefits
For the Six Months Ended June 30,
(In millions)	2017			2016			2017			2016
Service cost	$	37		$	90		$	—		$	—
Interest cost	246			275			2			3
Expected return on plan assets	(454		)	(483		)	—			—
Amortization of prior service cost (credit)	(1		)	(1		)	1			2
Recognized actuarial loss (gain)	83			84			—			(1		)
Net periodic benefit (credit) cost	$	(89	)	$	(35	)	$	3		$	4
Curtailment gain	(1		)	(5		)	—			—
Settlement loss	1			1			—			—
Total (credit) cost	$	(89	)	$	(39	)	$	3		$	4
U.S. Plans only	Pension Benefits						Post-retirement Benefits
For the Three Months Ended June 30,
(In millions)	2017			2016			2017			2016
Service cost	$	—		$	27		$	—		$	—
Interest cost	66			66			1			—
Expected return on plan assets	(90		)	(95		)	—			—
Amortization of prior service cost	—			—			1			1
Recognized actuarial loss (gain)	10			18			(1		)	—
Net periodic benefit (credit) cost	$	(14	)	$	16		$	1		$	1

U.S. Plans only	Pension Benefits						Post-retirement Benefits
For the Six Months Ended June 30,
(In millions)	2017			2016			2017			2016
Service cost	$	—		$	53		$	—		$	—
Interest cost	132			132			1			1
Expected return on plan assets	(179		)	(190		)	—			—
Amortization of prior service cost	—			—			2			2
Recognized actuarial loss (gain)	19			36			(1		)	(1		)
Net periodic benefit (credit) cost	$	(28	)	$	31		$	2		$	2

In October 2016, the Company modified its U.S. defined benefit pension plans to discontinue further benefit accruals for participants after December 31, 2016. At the same time, the Company amended its U.S. defined contribution retirement plans for most of its U.S. employees to add an automatic Company contribution equal to 4% of eligible base pay beginning on January 1, 2017. This new Company contribution, together with the Company’s current matching contribution, provides eligible U.S. employees with the opportunity to receive a total contribution of up to 7% of eligible base pay. In addition, the U.S. qualified defined benefit plans were merged effective December 30, 2016.

Significant non-U.S. plans only	Pension Benefits						Post-retirement Benefits
For the Three Months Ended June 30,
(In millions)	2017			2016			2017			2016
Service cost	$	19		$	19		$	—		$	—
Interest cost	58			72			—			1
Expected return on plan assets	(140		)	(147		)	—			—
Amortization of prior service credit	(1		)	(1		)	(1		)	—
Recognized actuarial loss	33			24			1			—
Net periodic benefit (credit) cost	$	(31	)	$	(33	)	$	—		$	1
Curtailment gain	—			(5		)	—			—
Settlement loss	—			1			—			—
Total (credit) cost	$	(31	)	$	(37	)	$	—		$	1

Significant non-U.S. plans only	Pension Benefits						Post-retirement Benefits
For the Six Months Ended June 30,
(In millions)	2017			2016			2017			2016
Service cost	$	37		$	37		$	—		$	—
Interest cost	114			143			1			2
Expected return on plan assets	(275		)	(293		)	—			—
Amortization of prior service credit	(1		)	(1		)	(1		)	—
Recognized actuarial loss	64			48			1			—
Net periodic benefit (credit) cost	$	(61	)	$	(66	)	$	1		$	2
Curtailment gain	(1		)	(5		)	—			—
Settlement loss	1			1			—			—
Total (credit) cost	$	(61	)	$	(70	)	$	1		$	2

In March 2017, the Company modified its defined benefit pension plans in Canada to discontinue further benefit accruals for participants after December 31, 2017 and replaced them with a defined contribution arrangement. The Company also amended its post-retirement benefits plan in Canada so that individuals who retire after April 1, 2019 will not be eligible to participate, except in certain situations. The Company re-measured the assets and liabilities of the plans, based on assumptions and market conditions on the amendment date.

The weighted average actuarial assumptions utilized to calculate the net periodic benefit costs for the U.S. and significant non-U.S. defined benefit plans are as follows:

Combined U.S. and significant non-U.S. plans	Pension Benefits				Post-retirement Benefits
June 30,	2017		2016		2017		2016
Weighted average assumptions:
Expected return on plan assets	6.64	%	7.07	%	—		—
Discount rate	3.40	%	4.11	%	3.64	%	4.12	%
Rate of compensation increase*	1.77	%	2.44	%	—		—

*The 2017 assumption does not include a rate of compensation increase for the U.S. defined benefit plans since future benefit accruals were discontinued for those plans after December 31, 2016.

The Company made approximately $120 million of contributions to its U.S. and non-U.S. defined benefit plans in the first six months of 2017. The Company expects to contribute approximately $136 million to its U.S. pension and non-U.S. pension plans during the remainder of 2017.

Defined Contribution Plans

The Company maintains certain defined contribution plans for its employees, the most significant being in the U.S. and the U.K. The cost of these U.S. and U.K. defined contribution plans was $65 million and $38 million for the six months ended June 30,2017 and 2016, respectively.

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Debt

6 Months Ended

Jun. 30, 2017

Debt Disclosure [Abstract]

Debt

Debt

The Company’s outstanding debt is as follows:

(In millions)	June 30, 2017		December 31, 2016
Short-term:
Commercial paper	$	150	$	50
Current portion of long-term debt	12		262
	162		312
Long-term:
Senior notes – 2.30% due 2017	—		250
Senior notes – 2.55% due 2018	249		249
Senior notes – 2.35% due 2019	299		299
Senior notes – 2.35% due 2020	498		497
Senior notes – 4.80% due 2021	498		498
Senior notes – 2.75% due 2022	496		—
Senior notes – 3.30% due 2023	347		347
Senior notes – 4.05% due 2023	248		248
Senior notes – 3.50% due 2024	596		596
Senior notes – 3.50% due 2025	496		495
Senior notes – 3.75% due 2026	596		596
Senior notes – 5.875% due 2033	297		297
Senior notes – 4.35% due 2047	492		—
Mortgage – 5.70% due 2035	376		382
Other	3		3
	5,491		4,757
Less current portion	12		262
	$	5,479	$	4,495

The senior notes in the table above are registered by the Company with the Securities and Exchange Commission and are not guaranteed.

The Company has established a short-term debt financing program of up to $1.5 billion through the issuance of commercial paper. The proceeds from the issuance of commercial paper are used for general corporate purposes. The Company had $150 million of commercial paper outstanding at June 30, 2017 at an effective interest rate of 1.45%.

In January 2017, the Company issued $500 million of 2.75% senior notes due 2022 and $500 million of 4.35% senior notes due 2047. The Company used the net proceeds for general corporate purposes, including the repayment of a $250 million debt maturity in April 2017.

In March 2016, the Company issued $350 million of 3.30%seven-year senior notes. The Company used the net proceeds for general corporate purposes.

The Company and certain of its foreign subsidiaries maintain a $1.5 billion multi-currency five-year unsecured revolving credit facility. The interest rate on this facility is based on LIBOR plus a fixed margin which varies with the Company's credit ratings. This facility expires in November 2020 and requires the Company to maintain certain coverage and leverage ratios which are tested quarterly. There were no borrowings outstanding under this facility at June 30, 2017.

Fair Value of Short-term and Long-term Debt

The estimated fair value of the Company’s short-term and long-term debt is provided below. Certain estimates and judgments were required to develop the fair value amounts. The fair value amounts shown below are not necessarily indicative of the amounts that the Company would realize upon disposition, nor do they indicate the Company’s intent or need to dispose of the financial instrument.

	June 30, 2017				December 31, 2016
(In millions)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Short-term debt	$	162	$	162	$	312	$	313
Long-term debt	$	5,479	$	5,714	$	4,495	$	4,625

The fair value of the Company’s short-term debt consists primarily of commercial paper and term debt maturing within the next year and its fair value approximates its carrying value. The estimated fair value of a primary portion of the Company's long-term debt is based on discounted future cash flows using current interest rates available for debt with similar terms and remaining maturities. Short- and long-term debt would be classified as Level 2 in the fair value hierarchy.

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Restructuring Costs

6 Months Ended

Jun. 30, 2017

Restructuring and Related Activities [Abstract]

Restructuring Costs

Restructuring Costs

The Company recorded total restructuring costs of $24 million in the first six months of 2017, primarily for severance at Mercer and future rent under non-cancelable leases. These costs were incurred in Risk and Insurance Services ($4 million), Consulting ($16 million) and Corporate ($4 million).

Details of the restructuring activity from January 1, 2016 through June 30, 2017, which includes liabilities from actions prior to 2017, are as follows:

(In millions)	Liability at 1/1/16		Amounts Accrued		Cash Paid			Other			Liability at 12/31/16		Amounts Accrued		Cash Paid			Other			Liability at 6/30/17
Severance	$	15	$	40	$	(22	)	$	(1	)	$	32	$	19	$	(30	)	$	(2	)	$	19
Future rent under non-cancelable leases and other costs	78		4		(17		)	(4		)	61		5		(9		)	(2		)	55
Total	$	93	$	44	$	(39	)	$	(5	)	$	93	$	24	$	(39	)	$	(4	)	$	74

The expenses associated with the above initiatives are included in compensation and benefits and other operating expenses in the consolidated statements of income. The liabilities associated with these initiatives are classified on the consolidated balance sheets as accounts payable and accrued liabilities, other liabilities or accrued compensation and employee benefits, depending on the nature of the items.

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Common Stock

6 Months Ended

Jun. 30, 2017

Equity [Abstract]

Common Stock

Common Stock

During the first six months of 2017, the Company repurchased approximately 5.4 million shares of its common stock for consideration of $400 million. During the first six months of 2016, the Company repurchased approximately 7.0 million shares of its common stock for consideration of $425 million. In November 2016, the Board of Directors of the Company authorized the Company to repurchase up to $2.5 billion in shares of the Company's common stock, which superseded any prior authorizations. As of June 30, 2017, the Company remained authorized to repurchase up to approximately $2 billion in shares of its common stock. There is no time limit on the authorization.

The Company issued approximately 3.7 million and 4.1 million shares related to stock compensation and employee stock purchase plans during the first six months of 2017 and 2016, respectively.

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Claims, Lawsuits And Other Contingencies

6 Months Ended

Jun. 30, 2017

Commitments and Contingencies Disclosure [Abstract]

Claims, Lawsuits, and Other Contingencies

Claims, Lawsuits and Other Contingencies

Litigation Matters

The Company and its subsidiaries are subject to a significant number of claims, lawsuits and proceedings in the ordinary course of business. Such claims and lawsuits consist principally of alleged errors and omissions in connection with the performance of professional services, including the placement of insurance, the provision of actuarial services for corporate and public sector clients, the provision of investment advice and investment management services to pension plans, the provision of advice relating to pension buy-out transactions and the provision of consulting services relating to the drafting and interpretation of trust deeds and other documentation governing pension plans. These claims typically seek damages, including punitive and treble damages, in amounts that could be significant. In establishing liabilities for errors and omissions claims in accordance with FASB ASC Subtopic No. 450-20 (Contingencies-Loss Contingencies), the Company uses case level reviews by inside and outside counsel, and internal actuarial analysis by Oliver Wyman Group, a subsidiary of the Company, and other methods to estimate potential losses. A liability is established when a loss is both probable and reasonably estimable. The liability is reviewed quarterly and adjusted as developments warrant. In many cases, the Company has not recorded a liability, other than for legal fees to defend the claim, because we are unable, at the present time, to make a determination that a loss is both probable and reasonably estimable.

To the extent that expected losses exceed our deductible in any policy year, the Company also records an asset for the amount that we expect to recover under any available third-party insurance programs. The Company has varying levels of third-party insurance coverage, with policy limits and coverage terms varying significantly by policy year.

Governmental Inquiries and Enforcement Matters

Our activities are regulated under the laws of the United States and its various states, the European Union and its member states, and the other jurisdictions in which the Company operates.

In April 2017, the Financial Conduct Authority in the United Kingdom (the "FCA") commenced a civil competition investigation into the aviation insurance and reinsurance sector. In connection with that investigation, the FCA carried out an on-site inspection at the London office of Marsh Limited, our Marsh and Guy Carpenter operating subsidiary in the United Kingdom. The FCA indicated that it had reasonable grounds for suspecting that Marsh Limited and other participants in the market have been sharing competitively sensitive information within the aviation insurance and reinsurance broking sector.

In July 2017, the Directorate-General for Competition of the European Commission and the Irish Competition and Consumer Protection Commission conducted on-site inspections at the offices of Marsh and other brokers in Dublin in connection with an investigation into potential anti-competitive practices in the commercial motor insurance market in the Republic of Ireland.

We are cooperating fully with these investigations and are conducting our own reviews. As these investigations are at early stages, we are unable to predict their likely timing, outcome or ultimate impact. There can be no assurance that the ultimate resolution of these or any related matters will not have a material adverse effect on our consolidated financial position, results of operations or liquidity.

In June 2017, the FCA issued a final report in connection with a market study of the U.K. asset management industry, which includes asset managers and investment consultants, including Mercer. In its report, the FCA indicated it would likely make a market investigation referral with respect to the investment consulting industry to the U.K. Competition & Markets Authority (the "CMA"). The FCA expects to announce a final decision regarding its referral to the CMA in September 2017.

In the ordinary course of business, the Company is also subject to other investigations, subpoenas, lawsuits and other regulatory actions undertaken by governmental authorities.

Other Contingencies-Guarantees

In connection with its acquisition of U.K.-based Sedgwick Group in 1998, the Company acquired several insurance underwriting businesses that were already in run-off, including River Thames Insurance Company Limited ("River Thames"), which the Company sold in 2001. Sedgwick guaranteed payment of claims on certain policies underwritten through the Institute of London Underwriters (the "ILU") by River Thames. The policies covered by this guarantee were reinsured up to £40 million by a related party of River Thames. Payment of claims under the reinsurance agreement is collateralized by segregated assets held in a trust. As of June 30, 2017, the reinsurance coverage exceeded the best estimate of the projected liability of the policies covered by the guarantee. To the extent River Thames or the reinsurer is unable to meet its obligations under those policies, a claimant may seek to recover from the Company under the guarantee.

From 1980 to 1983, the Company owned indirectly the English & American Insurance Company ("E&A"), which was a member of the ILU. The ILU required the Company to guarantee a portion of E&A's obligations. After E&A became insolvent in 1993, the ILU agreed to discharge the guarantee in exchange for the Company's agreement to post an evergreen letter of credit that is available to pay claims by policyholders on certain E&A policies issued through the ILU and incepting between July 3, 1980 and October 6, 1983. Certain claims have been paid under the letter of credit and the Company anticipates that additional claimants may seek to recover against the letter of credit.

* * * *

The pending proceedings described above and other matters not explicitly described in this Note 14 on Claims, Lawsuits and Other Contingencies may expose the Company or its subsidiaries to liability for significant monetary damages, fines, penalties or other forms of relief. Where a loss is both probable and reasonably estimable, the Company establishes liabilities in accordance with FASB ASC Subtopic No. 450-20 (Contingencies - Loss Contingencies). Except as described above, the Company is not able at this time to provide a reasonable estimate of the range of possible loss attributable to these matters or the impact they may have on the Company's consolidated results of operations, financial position or cash flows. This is primarily because these matters are still developing and involve complex issues subject to inherent uncertainty. Adverse determinations in one or more of these matters could have a material impact on the Company's consolidated results of operations, financial condition or cash flows in a future period.

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Segment Information

6 Months Ended

Jun. 30, 2017

Segment Reporting [Abstract]

Segment Information

Segment Information

The Company is organized based on the types of services provided. Under this structure, the Company’s segments are:

▪ Risk and Insurance Services, comprising insurance services (Marsh) and reinsurance services (Guy Carpenter); and

▪ Consulting, comprising Mercer and Oliver Wyman Group.

The accounting policies of the segments are the same as those used for the consolidated financial statements described in Note 1 to the Company’s 2016 Form 10-K. Segment performance is evaluated based on segment operating income, which includes directly related expenses, and charges or credits related to integration and restructuring but not the Company’s corporate-level expenses. Revenues are attributed to geographic areas on the basis of where the services are performed.

Selected information about the Company’s operating segments for the three and six-month periods ended June 30, 2017 and 2016 are as follows:

	Three Months Ended June 30,							Six Months Ended June 30,
(In millions)	Revenue				Operating Income (Loss)			Revenue				Operating Income (Loss)
2017–
Risk and Insurance Services	$	1,916		(a)	$	528		$	3,905		(c)	$	1,141
Consulting	1,592			(b)	283			3,118			(d)	524
Total Operating Segments	3,508				811			7,023				1,665
Corporate / Eliminations	(13		)		(47		)	(25		)		(92		)
Total Consolidated	$	3,495			$	764		$	6,998			$	1,573
2016–
Risk and Insurance Services	$	1,850		(a)	$	490		$	3,718		(c)	$	1,025
Consulting	1,539			(b)	285			3,017			(d)	530
Total Operating Segments	3,389				775			6,735				1,555
Corporate / Eliminations	(13		)		(49		)	(23		)		(96		)
Total Consolidated	$	3,376			$	726		$	6,712			$	1,459

^(a)  Includes inter-segment revenue of $4 million and $3 million in 2017and2016, respectively, interest income on fiduciary funds of $9 million and $6 million in 2017 and 2016, respectively, and equity method income of $7 million and $6 million in 2017 and 2016, respectively.

^(b)  Includes inter-segment revenue of $9 million and $10 million in 2017 and 2016, respectively, interest income on fiduciary funds of less than $1 million in both 2017 and 2016, and equity method income of $5 million in both 2017 and 2016.

^(c)  Includes inter-segment revenue of $4 million in both 2017 and 2016, interest income on fiduciary funds of $17 million and $12 million in 2017 and 2016, respectively, and equity method income of $9 million and $7 million in 2017 and 2016, respectively.

^(d)  Includes inter-segment revenue of $21 million and $19 million in 2017 and 2016, respectively, interest income on fiduciary funds of $1 million in both 2017 and 2016, and equity method income of $9 million in both 2017 and 2016.

Details of operating segment revenue for the three and six month period ended June 30, 2017 and 2016 are as follows:

	Three Months Ended June 30,						Six Months Ended June 30,
(In millions)	2017			2016			2017			2016
Risk and Insurance Services
Marsh	$	1,621		$	1,564		$	3,223		$	3,057
Guy Carpenter	295			286			682			661
Total Risk and Insurance Services	1,916			1,850			3,905			3,718
Consulting
Mercer	1,109			1,079			2,186			2,118
Oliver Wyman Group	483			460			932			899
Total Consulting	1,592			1,539			3,118			3,017
Total Operating Segments	3,508			3,389			7,023			6,735
Corporate / Eliminations	(13		)	(13		)	(25		)	(23		)
Total	$	3,495		$	3,376		$	6,998		$	6,712

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New Accounting Guidance

6 Months Ended

Jun. 30, 2017

New Accounting Pronouncements and Changes in Accounting Principles [Abstract]

New Accounting Guidance

New Accounting Guidance

In March 2017, the FASB issued new guidance that changes the presentation of net periodic pension cost and net periodic postretirement cost (''net periodic benefit costs"). The new guidance requires employers to report the service cost component of net periodic benefit costs in the same line item as other compensation costs in the income statement. The other components of net periodic benefit costs are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations, if one is presented. In addition, only the service cost component is eligible for capitalization, when applicable. The guidance is effective for annual periods beginning after December 15, 2017, including interim periods within those annual periods. Early adoption is permitted as of the beginning of an annual period for which financial statements (interim or annual) have not been issued or made available for issuance. The new guidance requires retrospective application for the presentation of the service cost component and the other components of net periodic benefit costs, and prospective application for the capitalization of the service cost component. The adoption of this guidance will impact the presentation of the Company's results of operations, in particular, reducing net operating income, but will have no impact on the Company's net income.

In January 2017, the FASB issued new guidance to simplify the test for goodwill impairment. The new guidance eliminates the second step in the current two-step goodwill impairment process, under which a goodwill impairment loss is measured by comparing the implied fair value of a reporting unit's goodwill with the carrying amount of that goodwill for that reporting unit. The new guidance requires a one-step impairment test, in which the goodwill impairment charge is based on 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. An entity still has the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. The guidance should be applied on a prospective basis with the nature of and reason for the change in accounting principle disclosed upon transition. The guidance is effective for annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted. The Company does not expect the adoption of this standard to have a material impact on the Company's financial position or results of operations.

In January 2017, the FASB issued guidance which clarifies the definition of a business in order to assist companies with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The guidance is effective for annual periods beginning after December 15, 2017, including interim periods within those annual periods. Early adoption is permitted under certain circumstances and the guidance must be applied prospectively as of the beginning of the period of adoption. The Company is currently evaluating the impact, if any, the adoption of this standard will have on its financial position or results of operations.

In November 2016, the FASB issued new guidance which requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents and amounts generally described as restricted cash or restricted cash equivalents. As a result, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The new guidance is effective for public companies for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The guidance must be applied retrospectively to all periods presented. Early adoption is permitted. The adoption of this guidance is not expected to have an impact on the Company's consolidated balance sheets or consolidated statements of cash flows.

In October 2016, the FASB also issued new guidance which requires an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. The new guidance eliminates the exception for an intra-entity transfer of an asset other than inventory. The new guidance is effective for public companies for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Early adoption is permitted. The new guidance must be applied on a modified retrospective basis through a cumulative-effect adjustment to retained earnings as of the beginning of the period of adoption. The Company is currently evaluating the impact the adoption of this standard will have on its financial position and results of operations.

In August 2016, the FASB issued new guidance which adds or clarifies guidance on the classification of certain cash receipts and payments in the statement of cash flows, including cash payments for debt prepayments or debt extinguishment costs, contingent consideration payments made after a business combination and distributions received from equity method investees. The guidance is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The guidance must be applied retrospectively to all periods presented unless retrospective application is impracticable. Early adoption is permitted. The Company is currently evaluating the impact the guidance will have on its statement of cash flows.

In February 2016, the FASB issued new guidance intended to improve financial reporting for leases. Under the new guidance, a lessee will be required to recognize assets and liabilities for leases with lease terms of more than 12 months. Consistent with current GAAP, the recognition, measurement, and presentation of expenses and cash flows arising from a lease by a lessee primarily will depend on its classification as a financing or operating lease. However, unlike current GAAP, which requires that only capital leases be recognized on the balance sheet, the new guidance requires that both types of leases be recognized on the balance sheet. The new guidance will require additional disclosures to help investors and other financial statement users better understand the amount, timing, and uncertainty of cash flows arising from leases. These disclosures include qualitative and quantitative requirements, and additional information about the amounts recorded in the financial statements. The accounting by organizations that own the assets ("lessor") leased by the lessee will remain largely unchanged from current GAAP. However, the guidance contains some targeted improvements that are intended to align, where necessary, lessor accounting with the lessee accounting model and with the updated revenue recognition guidance issued in 2014. The new guidance on leases will take effect for public companies for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early application will be permitted. The Company is currently evaluating the impact the adoption of the guidance will have on its financial position and results of operations, but expects material "right to use" assets and lease liabilities to be recorded on its consolidated balance sheets.

In January 2016, the FASB issued new guidance intended to improve the recognition and measurement of financial instruments. The new guidance requires equity investments (except those accounted for under the equity method of accounting, or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income; requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes; requires separate presentation of financial assets and financial liabilities by measurement category and form of financial asset (i.e., securities or loans and receivables) on the balance sheet or the accompanying notes to the financial statements; eliminates the requirement for public business entities to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet; and requires a reporting organization to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk (also referred to as "own credit") when the organization has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. The new guidance is effective for public companies for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The Company is currently evaluating the impact of the adoption of the guidance on its financial position and results of operations.

New Revenue Recognition Pronouncement

In May 2014, the FASB issued new accounting guidance to clarify the principles for revenue recognition. The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. To achieve that principle, the entity should apply the following steps: identify the contract(s) with the customer, identify the performance obligations in the contract(s), determine the transaction price, allocate the transaction price to the performance obligations in the contract and recognize revenue when (or as) the entity satisfies a performance obligation. Entities are permitted to adopt the guidance under one of the following methods: the "full retrospective" method, which applies the guidance to each period presented (prior years restated) or the "modified retrospective" method in which the guidance is only applied to the year of adoption, with the cumulative effect of initially applying the guidance recognized as an adjustment to retained earnings. The Company will adopt the new guidance effective January 1, 2018. The Company is evaluating the transition method it will use, but currently expects to use the modified retrospective method.

The Company continues to evaluate the impact of the new standard. Based on the results of our reviews to date, the Company expects there will be significant movement in the quarterly timing of revenue recognition in the Risk and Insurance Services segment. In particular, in the Company’s reinsurance broking operations recognition of revenue will be accelerated under the new standard. Currently, revenue related to certain reinsurance placements is recognized on the later of billing or effective date as premiums are written and attached to the reinsurance treaties. This typically results in revenue being recognized over a 12 to 24 month period. Under the new guidance, revenue will be recognized largely at the policy effective date, subject to the constraint as defined in the guidance. In the insurance brokerage operations, revenue from commission based arrangements will continue to be recorded at the policy effective date, while the timing of revenue recognition for certain fee based arrangements will shift among quarters. Since the vast majority of our fee arrangements involve contracts that cover a single year of services, the Company does not believe there will be a significant change to the amount of revenue recognized in an annual period once the standard is adopted. The Company is currently evaluating, designing and implementing changes in processes, controls and systems necessary to support the new revenue recognition requirements.

The Company's initial review and preliminary conclusions for the Consulting segment indicate the application of the new standard will not materially change the existing timing of revenue recognition in quarterly or annual periods. The conclusions will be completed following a final review of customer arrangement legal terms and conditions in certain non-U.S. locations.

The Company expects that certain costs that are currently expensed will be capitalized as costs to obtain or costs to fulfill customer contracts under guidance issued as part of the revenue recognition standard. Costs to obtain a contract, generally, would be amortized over the expected life of the underlying customer relationship. However, in many cases, costs to obtain a contract renewal are commensurate with the costs to obtain the initial contract. Those costs would have an amortization period of less than one year, and the Company would expect to use the practical expedient available in the standard and expense such costs as incurred. Any capitalized costs to fulfill a contract would be amortized on a basis consistent with the transfer of services to which they relate. Such expenses related to Risk and Insurance Services would generally be "amortized" over a period of one year or less. The Company is continuing to quantify the amount of such costs that must be deferred. In the Consulting segment, certain implementation expenses that are currently deferred may have a longer amortization period to reflect the amortization over the expected life of the contract including anticipated renewal periods.

The Company has not yet fully quantified the impact of the changes discussed above. However, the Company expects that it will recognize a significant amount of contract assets and/or receivables upon implementation of the standard, related to both the contract assets for capitalized costs to obtain and fulfill contracts, as well as commissions receivable related to reinsurance brokerage activity.

New Accounting Pronouncements Recently Adopted

In October 2016, the FASB issued new guidance which changes the evaluation of whether a reporting entity is the primary beneficiary of a variable interest entity by changing how a reporting entity that is a single decision maker of a variable interest entity treats indirect interests in the entity held through related parties that are under common control with the reporting entity. If a reporting entity satisfies the first characteristic of a primary beneficiary (such that it is the single decision maker of a variable interest entity), the new guidance requires that reporting entity, in determining whether it satisfies the second characteristic of a primary beneficiary, to include all of its direct variable interest in a variable interest entity and, on a proportionate basis, its indirect variable interests in a variable interest entity held through related parties, including related parties that are under common control with the reporting entity. The adoption of this guidance did not have a significant impact on its financial position, results of operations and statement of cash flows.

In April 2016, the FASB issued new guidance which simplifies several aspects of the accounting for employee share-based payment transactions, including the accounting for income taxes, forfeitures and statutory tax withholding requirements, as well as classification in the statement of cash flows. The new guidance requires that companies record all excess tax benefits and tax deficiencies as an income tax benefit or expense in the income statement and classify excess tax benefits as an operating activity in the statement of cash flows. The Company adopted this new guidance prospectively, effective January 1, 2017 and prior periods have not been adjusted. For the six months ended June 30, 2017, the adoption of this new standard reduced income tax expense in the consolidated statement of income by approximately $48 million. For the six months ended June 30, 2016, the Company recorded an excess tax benefit of $24 million as an increase to equity in its consolidated balance sheet, which was reflected as cash provided by financing activities in the consolidated statement of cash flows.

In March 2016, the FASB issued new guidance which eliminates the requirement that when an investment qualifies for use of the equity method as a result of an increase in the level of ownership interest or degree of influence, an investor must adjust the investment, results of operations and retained earnings retroactively on a step-by-step basis as if the equity method had been in effect during all previous periods that the investment had been held. The amendments require that the equity method investor add the cost of acquiring the additional interest in the investee to the current basis of the investor’s previously held interest and adopt the equity method of accounting as of the date the investment becomes qualified for equity method accounting. Therefore, upon qualifying for the equity method of accounting, no retroactive adjustment of the investment is required. The amendments require that an entity that has an available-for-sale equity security that becomes qualified for the equity method of accounting recognize through earnings the unrealized holding gain or loss in accumulated other comprehensive income at the date the investment becomes qualified for use of the equity method. The new guidance is effective for all entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2016. The guidance was adopted on January 1, 2017 and did not have an impact on the Company's financial position or results of operations.

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Principles of Consolidation and Other Matters (Policies)

6 Months Ended

Jun. 30, 2017

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of Accounting

The consolidated financial statements included herein have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission. While certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America have been omitted pursuant to such rules and regulations for interim filings, the Company believes that the information and disclosures presented are adequate to make such information and disclosures not misleading.

Cash and Cash Equivalents

Cash and cash equivalents primarily consist of certificates of deposit and time deposits, with original maturities of three months or less, and money market funds. The estimated fair value of the Company's cash and cash equivalents approximates their carrying value.

Investments

The Company holds investments in certain private equity funds. Investments in private equity funds are accounted for under the equity method of accounting using a consistently applied three-month lag period adjusted for any known significant changes from the lag period to the reporting date of the Company. The underlying private equity funds follow investment company accounting, where investments within the fund are carried at fair value. Investment gains or losses for the Company's proportionate share of the change in fair value of the funds are recorded in earnings. Investments accounted for using the equity method of accounting are included in other assets in the consolidated balance sheets.

The caption "Investment income (loss)" in the consolidated statements of income comprises realized and unrealized gains and losses from investments recognized in earnings. It includes, when applicable, other than temporary declines in the value of debt and available-for-sale securities and equity method gains or losses on the Company's investments in private equity funds.

Income Taxes

The Company's effective tax rate in the second quarter of 2017 was 28.6% compared with 29.5% in the second quarter of 2016. The effective tax rate for the first six months of 2017 and 2016 was 25.9% and 29.0%, respectively. The rates reflect foreign operations which are taxed at rates below the U.S. statutory tax rate, including the effect of repatriation, as well as the impact of discrete tax matters such as tax legislation, changes in valuation allowances, nontaxable adjustments to contingent acquisition consideration and, starting in 2017, excess tax benefits related to share-based compensation.

The Company is routinely examined by tax authorities in the jurisdictions in which it has significant operations. The Company regularly considers the likelihood of assessments in each of the taxing jurisdictions resulting from examinations. When evaluating the potential imposition of penalties, the Company considers a number of relevant factors under penalty statutes, including appropriate disclosure of the tax return position, the existence of legal authority supporting the Company's position, and reliance on the opinion of professional tax advisors.

The Company reports a liability for unrecognized tax benefits resulting from uncertain tax positions taken or expected to be taken in tax returns.

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Fair Value Measurements (Policies)

6 Months Ended

Jun. 30, 2017

Fair Value Disclosures [Abstract]

Fair Value Measurement

Fair Value Hierarchy

The Company has categorized its assets and liabilities that are valued at fair value on a recurring basis into a three-level fair value hierarchy as defined by the Financial Accounting Standards Board ("FASB"). The fair value hierarchy gives the highest priority to quoted prices in active markets for identical assets and liabilities (Level 1) and lowest priority to unobservable inputs (Level 3). In some cases, the inputs used to measure fair value might fall into different levels of the fair value hierarchy. In such cases, the level in the fair value hierarchy, for disclosure purposes, is determined based on the lowest level input that is significant to the fair value measurement. Assets and liabilities recorded in the consolidated balance sheets at fair value are categorized based on the inputs in the valuation techniques as follows:

Level 1. Assets and liabilities whose values are based on unadjusted quoted prices for identical assets or liabilities in an active market (examples include active exchange-traded equity securities and exchange-traded money market mutual funds).

Assets and liabilities measured using Level 1 inputs include exchange-traded equity securities, exchange-traded mutual funds and money market funds.

Level 2. Assets and liabilities whose values are based on the following:

a) Quoted prices for similar assets or liabilities in active markets;

b) Quoted prices for identical or similar assets or liabilities in non-active markets (examples include corporate and municipal bonds, which trade infrequently);

c) Pricing models whose inputs are observable for substantially the full term of the asset or liability (examples include most over-the-counter derivatives, including interest rate and currency swaps); and

d) Pricing models whose inputs are derived principally from or corroborated by observable market data through correlation or other means for substantially the full asset or liability (for example, certain mortgage loans).

The Company does not have any assets or liabilities that are measured using Level 2 inputs.

Level 3. Assets and liabilities whose values are based on prices, or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement. These inputs reflect management’s own assumptions about the assumptions a market participant would use in pricing the asset or liability.

Liabilities measured using Level 3 inputs include liabilities for contingent purchase consideration.

Valuation Techniques

Equity Securities, Money Market Funds and Mutual Funds – Level 1

Investments for which market quotations are readily available are valued at the sale price on their principal exchange or, for certain markets, official closing bid price. Money market funds are valued using a valuation technique that results in price per share at $1.00.

Contingent Purchase Consideration Liability – Level 3

Purchase consideration for some acquisitions made by the Company includes contingent consideration arrangements. These arrangements typically provide for the payment of additional consideration if earnings or revenue targets are met over periods from two to four years. The fair value of the contingent purchase consideration liability is estimated as the present value of future cash flows to be paid, based on projections of revenue and earnings and related targets of the acquired entities.

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New Accounting Guidance (Policies)

6 Months Ended

Jun. 30, 2017

New Accounting Pronouncements and Changes in Accounting Principles [Abstract]

New Accounting Pronouncements

New Accounting Guidance

In March 2017, the FASB issued new guidance that changes the presentation of net periodic pension cost and net periodic postretirement cost (''net periodic benefit costs"). The new guidance requires employers to report the service cost component of net periodic benefit costs in the same line item as other compensation costs in the income statement. The other components of net periodic benefit costs are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations, if one is presented. In addition, only the service cost component is eligible for capitalization, when applicable. The guidance is effective for annual periods beginning after December 15, 2017, including interim periods within those annual periods. Early adoption is permitted as of the beginning of an annual period for which financial statements (interim or annual) have not been issued or made available for issuance. The new guidance requires retrospective application for the presentation of the service cost component and the other components of net periodic benefit costs, and prospective application for the capitalization of the service cost component. The adoption of this guidance will impact the presentation of the Company's results of operations, in particular, reducing net operating income, but will have no impact on the Company's net income.

In January 2017, the FASB issued new guidance to simplify the test for goodwill impairment. The new guidance eliminates the second step in the current two-step goodwill impairment process, under which a goodwill impairment loss is measured by comparing the implied fair value of a reporting unit's goodwill with the carrying amount of that goodwill for that reporting unit. The new guidance requires a one-step impairment test, in which the goodwill impairment charge is based on 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. An entity still has the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. The guidance should be applied on a prospective basis with the nature of and reason for the change in accounting principle disclosed upon transition. The guidance is effective for annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted. The Company does not expect the adoption of this standard to have a material impact on the Company's financial position or results of operations.

In January 2017, the FASB issued guidance which clarifies the definition of a business in order to assist companies with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The guidance is effective for annual periods beginning after December 15, 2017, including interim periods within those annual periods. Early adoption is permitted under certain circumstances and the guidance must be applied prospectively as of the beginning of the period of adoption. The Company is currently evaluating the impact, if any, the adoption of this standard will have on its financial position or results of operations.

In November 2016, the FASB issued new guidance which requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents and amounts generally described as restricted cash or restricted cash equivalents. As a result, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The new guidance is effective for public companies for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The guidance must be applied retrospectively to all periods presented. Early adoption is permitted. The adoption of this guidance is not expected to have an impact on the Company's consolidated balance sheets or consolidated statements of cash flows.

In October 2016, the FASB also issued new guidance which requires an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. The new guidance eliminates the exception for an intra-entity transfer of an asset other than inventory. The new guidance is effective for public companies for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Early adoption is permitted. The new guidance must be applied on a modified retrospective basis through a cumulative-effect adjustment to retained earnings as of the beginning of the period of adoption. The Company is currently evaluating the impact the adoption of this standard will have on its financial position and results of operations.

In August 2016, the FASB issued new guidance which adds or clarifies guidance on the classification of certain cash receipts and payments in the statement of cash flows, including cash payments for debt prepayments or debt extinguishment costs, contingent consideration payments made after a business combination and distributions received from equity method investees. The guidance is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The guidance must be applied retrospectively to all periods presented unless retrospective application is impracticable. Early adoption is permitted. The Company is currently evaluating the impact the guidance will have on its statement of cash flows.

In February 2016, the FASB issued new guidance intended to improve financial reporting for leases. Under the new guidance, a lessee will be required to recognize assets and liabilities for leases with lease terms of more than 12 months. Consistent with current GAAP, the recognition, measurement, and presentation of expenses and cash flows arising from a lease by a lessee primarily will depend on its classification as a financing or operating lease. However, unlike current GAAP, which requires that only capital leases be recognized on the balance sheet, the new guidance requires that both types of leases be recognized on the balance sheet. The new guidance will require additional disclosures to help investors and other financial statement users better understand the amount, timing, and uncertainty of cash flows arising from leases. These disclosures include qualitative and quantitative requirements, and additional information about the amounts recorded in the financial statements. The accounting by organizations that own the assets ("lessor") leased by the lessee will remain largely unchanged from current GAAP. However, the guidance contains some targeted improvements that are intended to align, where necessary, lessor accounting with the lessee accounting model and with the updated revenue recognition guidance issued in 2014. The new guidance on leases will take effect for public companies for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early application will be permitted. The Company is currently evaluating the impact the adoption of the guidance will have on its financial position and results of operations, but expects material "right to use" assets and lease liabilities to be recorded on its consolidated balance sheets.

In January 2016, the FASB issued new guidance intended to improve the recognition and measurement of financial instruments. The new guidance requires equity investments (except those accounted for under the equity method of accounting, or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income; requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes; requires separate presentation of financial assets and financial liabilities by measurement category and form of financial asset (i.e., securities or loans and receivables) on the balance sheet or the accompanying notes to the financial statements; eliminates the requirement for public business entities to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet; and requires a reporting organization to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk (also referred to as "own credit") when the organization has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. The new guidance is effective for public companies for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The Company is currently evaluating the impact of the adoption of the guidance on its financial position and results of operations.

New Revenue Recognition Pronouncement

In May 2014, the FASB issued new accounting guidance to clarify the principles for revenue recognition. The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. To achieve that principle, the entity should apply the following steps: identify the contract(s) with the customer, identify the performance obligations in the contract(s), determine the transaction price, allocate the transaction price to the performance obligations in the contract and recognize revenue when (or as) the entity satisfies a performance obligation. Entities are permitted to adopt the guidance under one of the following methods: the "full retrospective" method, which applies the guidance to each period presented (prior years restated) or the "modified retrospective" method in which the guidance is only applied to the year of adoption, with the cumulative effect of initially applying the guidance recognized as an adjustment to retained earnings. The Company will adopt the new guidance effective January 1, 2018. The Company is evaluating the transition method it will use, but currently expects to use the modified retrospective method.

The Company continues to evaluate the impact of the new standard. Based on the results of our reviews to date, the Company expects there will be significant movement in the quarterly timing of revenue recognition in the Risk and Insurance Services segment. In particular, in the Company’s reinsurance broking operations recognition of revenue will be accelerated under the new standard. Currently, revenue related to certain reinsurance placements is recognized on the later of billing or effective date as premiums are written and attached to the reinsurance treaties. This typically results in revenue being recognized over a 12 to 24 month period. Under the new guidance, revenue will be recognized largely at the policy effective date, subject to the constraint as defined in the guidance. In the insurance brokerage operations, revenue from commission based arrangements will continue to be recorded at the policy effective date, while the timing of revenue recognition for certain fee based arrangements will shift among quarters. Since the vast majority of our fee arrangements involve contracts that cover a single year of services, the Company does not believe there will be a significant change to the amount of revenue recognized in an annual period once the standard is adopted. The Company is currently evaluating, designing and implementing changes in processes, controls and systems necessary to support the new revenue recognition requirements.

The Company's initial review and preliminary conclusions for the Consulting segment indicate the application of the new standard will not materially change the existing timing of revenue recognition in quarterly or annual periods. The conclusions will be completed following a final review of customer arrangement legal terms and conditions in certain non-U.S. locations.

The Company expects that certain costs that are currently expensed will be capitalized as costs to obtain or costs to fulfill customer contracts under guidance issued as part of the revenue recognition standard. Costs to obtain a contract, generally, would be amortized over the expected life of the underlying customer relationship. However, in many cases, costs to obtain a contract renewal are commensurate with the costs to obtain the initial contract. Those costs would have an amortization period of less than one year, and the Company would expect to use the practical expedient available in the standard and expense such costs as incurred. Any capitalized costs to fulfill a contract would be amortized on a basis consistent with the transfer of services to which they relate. Such expenses related to Risk and Insurance Services would generally be "amortized" over a period of one year or less. The Company is continuing to quantify the amount of such costs that must be deferred. In the Consulting segment, certain implementation expenses that are currently deferred may have a longer amortization period to reflect the amortization over the expected life of the contract including anticipated renewal periods.

The Company has not yet fully quantified the impact of the changes discussed above. However, the Company expects that it will recognize a significant amount of contract assets and/or receivables upon implementation of the standard, related to both the contract assets for capitalized costs to obtain and fulfill contracts, as well as commissions receivable related to reinsurance brokerage activity.

New Accounting Pronouncements Recently Adopted

In October 2016, the FASB issued new guidance which changes the evaluation of whether a reporting entity is the primary beneficiary of a variable interest entity by changing how a reporting entity that is a single decision maker of a variable interest entity treats indirect interests in the entity held through related parties that are under common control with the reporting entity. If a reporting entity satisfies the first characteristic of a primary beneficiary (such that it is the single decision maker of a variable interest entity), the new guidance requires that reporting entity, in determining whether it satisfies the second characteristic of a primary beneficiary, to include all of its direct variable interest in a variable interest entity and, on a proportionate basis, its indirect variable interests in a variable interest entity held through related parties, including related parties that are under common control with the reporting entity. The adoption of this guidance did not have a significant impact on its financial position, results of operations and statement of cash flows.

In April 2016, the FASB issued new guidance which simplifies several aspects of the accounting for employee share-based payment transactions, including the accounting for income taxes, forfeitures and statutory tax withholding requirements, as well as classification in the statement of cash flows. The new guidance requires that companies record all excess tax benefits and tax deficiencies as an income tax benefit or expense in the income statement and classify excess tax benefits as an operating activity in the statement of cash flows. The Company adopted this new guidance prospectively, effective January 1, 2017 and prior periods have not been adjusted. For the six months ended June 30, 2017, the adoption of this new standard reduced income tax expense in the consolidated statement of income by approximately $48 million. For the six months ended June 30, 2016, the Company recorded an excess tax benefit of $24 million as an increase to equity in its consolidated balance sheet, which was reflected as cash provided by financing activities in the consolidated statement of cash flows.

In March 2016, the FASB issued new guidance which eliminates the requirement that when an investment qualifies for use of the equity method as a result of an increase in the level of ownership interest or degree of influence, an investor must adjust the investment, results of operations and retained earnings retroactively on a step-by-step basis as if the equity method had been in effect during all previous periods that the investment had been held. The amendments require that the equity method investor add the cost of acquiring the additional interest in the investee to the current basis of the investor’s previously held interest and adopt the equity method of accounting as of the date the investment becomes qualified for equity method accounting. Therefore, upon qualifying for the equity method of accounting, no retroactive adjustment of the investment is required. The amendments require that an entity that has an available-for-sale equity security that becomes qualified for the equity method of accounting recognize through earnings the unrealized holding gain or loss in accumulated other comprehensive income at the date the investment becomes qualified for use of the equity method. The new guidance is effective for all entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2016. The guidance was adopted on January 1, 2017 and did not have an impact on the Company's financial position or results of operations.

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Per Share Data (Tables)

6 Months Ended

Jun. 30, 2017

Earnings Per Share [Abstract]

Diluted EPS Calculation Continuing Operations

Basic and Diluted EPS Calculation	Three Months Ended June 30,				Six Months Ended June 30,
(In millions, except per share amounts)	2017		2016		2017		2016
Basic weighted average common shares outstanding	514		521		514		521
Dilutive effect of potentially issuable common shares	6		4		7		5
Diluted weighted average common shares outstanding	520		525		521		526
Average stock price used to calculate common stock equivalents	$	75.41	$	64.17	$	73.36	$	60.01

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Supplemental Disclosures to the Consolidated Statements of Cash Flows (Tables)

6 Months Ended

Jun. 30, 2017

Supplemental Cash Flow Information [Abstract]

Additional Information Concerning Acquisitions, Interest and Income Taxes Paid

The following schedule provides additional information concerning acquisitions, interest and income taxes paid for the six-month periods ended June 30, 2017 and 2016.

(In millions)	2017			2016
Assets acquired, excluding cash	$	576		$	107
Liabilities assumed	(74		)	(4		)
Contingent/deferred purchase consideration	(90		)	(26		)
Net cash outflow for acquisitions	$	412		$	77

(In millions)	2017		2016
Interest paid	$	92	$	86
Income taxes paid, net of refunds	$	297	$	303

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Other Comprehensive Income (Loss) (Tables)

6 Months Ended

Jun. 30, 2017

Equity [Abstract]

Schedule of Accumulated Other Comprehensive Income (Loss)

The changes, net of tax, in the balances of each component of Accumulated Other Comprehensive Income ("AOCI") for the three and six-month periods ended June 30, 2017 and 2016, including amounts reclassified out of AOCI, are as follows:

(In millions)	Unrealized Investment Gains		Pension/Post-Retirement Plans Gains (Losses)			Foreign Currency Translation Gains (Losses)			Total Gains (Losses)
Balance as of April 1, 2017	$	16	$	(3,208	)	$	(1,645	)	$	(4,837	)
Other comprehensive income (loss) before reclassifications	14		(40		)	289			263
Amounts reclassified from accumulated other comprehensive income	—		33			—			33
Net current period other comprehensive income (loss)	14		(7		)	289			296
Balance as of June 30, 2017	$	30	$	(3,215	)	$	(1,356	)	$	(4,541	)

(In millions)	Unrealized Investment Gains		Pension/Post-Retirement Plans Gains (Losses)			Foreign Currency Translation Gains (Losses)			Total Gains (Losses)
Balance as of April 1, 2016	$	6	$	(3,014	)	$	(1,089	)	$	(4,097	)
Other comprehensive income (loss) before reclassifications	—		98			(333		)	(235		)
Amounts reclassified from accumulated other comprehensive income	—		31			—			31
Net current period other comprehensive income (loss)	—		129			(333		)	(204		)
Balance as of June 30, 2016	$	6	$	(2,885	)	$	(1,422	)	$	(4,301	)

(In millions)	Unrealized Investment Gains		Pension/Post-Retirement Plans Gains (Losses)			Foreign Currency Translation Gains (Losses)			Total Gains (Losses)
Balance as of January 1, 2017	$	19	$	(3,232	)	$	(1,880	)	$	(5,093	)
Other comprehensive income (loss) before reclassifications	11		(46		)	524			489
Amounts reclassified from accumulated other comprehensive income	—		63			—			63
Net current period other comprehensive income (loss)	11		17			524			552
Balance as of June 30, 2017	$	30	$	(3,215	)	$	(1,356	)	$	(4,541	)

(In millions)	Unrealized Investment Gains		Pension/Post-Retirement Plans Gains (Losses)			Foreign Currency Translation Gains (Losses)			Total Gains (Losses)
Balance as of January 1, 2016	$	6	$	(3,124	)	$	(1,102	)	$	(4,220	)
Other comprehensive income (loss) before reclassifications	—		178			(320		)	(142		)
Amounts reclassified from accumulated other comprehensive income	—		61			—			61
Net current period other comprehensive income (loss)	—		239			(320		)	(81		)
Balance as of June 30, 2016	$	6	$	(2,885	)	$	(1,422	)	$	(4,301	)

Schedule of Components of Comprehensive Income (Loss)

The components of other comprehensive income (loss) for the three and six-month periods ended June 30, 2017 and 2016 are as follows:

Three Months Ended June 30,	2017									2016
(In millions)	Pre-Tax			Tax (Credit)			Net of Tax			Pre-Tax			Tax (Credit)			Net of Tax
Foreign currency translation adjustments	$	290		$	1		$	289		$	(334	)	$	(1	)	$	(333	)
Unrealized investment gains	24			10			14			—			—			—
Pension/post-retirement plans:
Amortization of losses included in net periodic pension cost:
Net actuarial losses (a)	42			9			33			43			12			31
Subtotal	42			9			33			43			12			31
Effect of remeasurement	—			1			(1		)	—			—			—
Effect of curtailment	—			—			—			3			1			2
Foreign currency translation (losses) gains	(47		)	(8		)	(39		)	116			21			95
Other	—			—			—			1			—			1
Pension/post-retirement plans gains (losses)	(5		)	2			(7		)	163			34			129
Other comprehensive income (loss)	$	309		$	13		$	296		$	(171	)	$	33		$	(204	)
(a) Components of net periodic pension cost are included in compensation and benefits in the consolidated statements of income. Income tax credits on prior service losses and net actuarial losses are included in income tax expense.

Six Months Ended June 30,	2017									2016
(In millions)	Pre-Tax			Tax (Credit)			Net of Tax			Pre-Tax			Tax (Credit)			Net of Tax
Foreign currency translation adjustments	$	525		$	1		$	524		$	(321	)	$	(1	)	$	(320	)
Unrealized investment gains	19			8			11			—			—			—
Pension/post-retirement plans:
Amortization of losses included in net periodic pension cost:
Prior service cost (a)	—			—			—			1			—			1
Net actuarial losses (a)	82			19			63			84			24			60
Subtotal	82			19			63			85			24			61
Effect of remeasurement	9			3			6			(1		)	—			(1		)
Effect of curtailment	(1		)	—			(1		)	3			1			2
Effect of settlement	1			—			1			1			—			1
Foreign currency translation (losses) gains	(62		)	(11		)	(51		)	213			37			176
Other	(1		)	—			(1		)	—			—			—
Pension/post-retirement plans gains	28			11			17			301			62			239
Other comprehensive income (loss)	$	572		$	20		$	552		$	(20	)	$	61		$	(81	)
(a) Components of net periodic pension cost are included in compensation and benefits in the consolidated statements of income. Tax on prior service gains and net actuarial losses is included in income tax expense.

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Acquisitions (Tables)

6 Months Ended

Jun. 30, 2017

Business Combinations [Abstract]

Schedule For Allocation of Acquisition Costs

The following table presents the preliminary allocation of the acquisition cost to the assets acquired and liabilities assumed during 2017 based on their fair values:

For the Six Months Ended June 30, 2017
(In millions)
Cash	$	420
Estimated fair value of deferred/contingent consideration	90
Total Consideration	$	510
Allocation of purchase price:
Cash and cash equivalents	$	8
Accounts receivable, net	7
Property, plant, and equipment	3
Other intangible assets	196
Goodwill	370
Total assets acquired	584
Current liabilities	4
Other liabilities	70
Total liabilities assumed	74
Net assets acquired	$	510

Schedule of Acquired Finite-Lived Intangible Assets by Major Class

The following chart provides information about other intangible assets acquired during 2017:

	Amount		Weighted Average Amortization Period
Client relationships	$	184	13 years
Other	12		4 years
	$	196

Pro-Forma Information

The unaudited pro-forma financial data is presented for illustrative purposes only and is not necessarily indicative of the operating results that would have been achieved if such acquisitions had occurred on the dates indicated, nor is it necessarily indicative of future consolidated results.

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions, except per share figures)	2017		2016		2017		2016
Revenue	$	3,496	$	3,493	$	7,011	$	6,951
Net income attributable to the Company	$	502	$	470	$	1,072	$	950
Basic net income per share attributable to the Company	$	0.98	$	0.90	$	2.08	$	1.82
Diluted net income per share attributable to the Company	$	0.96	$	0.89	$	2.06	$	1.81

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Goodwill and Other Intangibles (Tables)

6 Months Ended

Jun. 30, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Changes in the Carrying Amount of Goodwill

Changes in the carrying amount of goodwill are as follows:

June 30,
(In millions)	2017		2016
Balance as of January 1, as reported	$	8,369	$	7,889
Goodwill acquired	370		62
Other adjustments(a)	82		(6		)
Balance at June 30,	$	8,821	$	7,945

Amortized Intangible Assets

The gross cost and accumulated amortization at June 30, 2017 and December 31, 2016 are as follows:

	June 30, 2017						December 31, 2016
(In millions)	Gross Cost		Accumulated Amortization		Net Carrying Amount		Gross Cost		Accumulated Amortization		Net Carrying Amount
Client Relationships	$	1,581	$	453	$	1,128	$	1,390	$	392	$	998
Other (a)	198		93		105		204		76		128
Amortized intangibles	$	1,779	$	546	$	1,233	$	1,594	$	468	$	1,126

^(a) Primarily non-compete agreements, trade names and developed technology.

Estimated Future Aggregate Amortization Expense

The estimated future aggregate amortization expense is as follows:

For the Years Ending December 31,
(In millions)	Estimated Expense
2017 (excludes amortization through June 30, 2017)	$	85
2018	158
2019	149
2020	127
2021	118
Subsequent years	596
	$	1,233

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Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2017

Fair Value Disclosures [Abstract]

Assets and Liabilities Measured at Fair Value on a Recurring Basis

The following fair value hierarchy table presents information about the Company’s assets and liabilities measured at fair value on a recurring basis as of June 30, 2017 and December 31, 2016.

	Identical Assets (Level 1)				Observable Inputs (Level 2)				Unobservable Inputs (Level 3)				Total
(In millions)	06/30/17		12/31/16		06/30/17		12/31/16		06/30/17		12/31/16		06/30/17		12/31/16
Assets:
Financial instruments owned:
Exchange traded equity securities(a)	$	107	$	89	$	—	$	—	$	—	$	—	$	107	$	89
Mutual funds(a)	140		141		—		—		—		—		140		141
Money market funds(b)	36		22		—		—		—		—		36		22
Total assets measured at fair value	$	283	$	252	$	—	$	—	$	—	$	—	$	283	$	252
Fiduciary Assets:
Money market funds	$	82	$	90	$	—	$	—	$	—	$	—	$	82	$	90
Total fiduciary assets measured at fair value	$	82	$	90	$	—	$	—	$	—	$	—	$	82	$	90
Liabilities:
Contingent purchase consideration liability(c)	$	—	$	—	$	—	$	—	$	203	$	241	$	203	$	241
Total liabilities measured at fair value	$	—	$	—	$	—	$	—	$	203	$	241	$	203	$	241

^(a)  Included in other assets in the consolidated balance sheets.

^(b)  Included in cash and cash equivalents in the consolidated balance sheets.

^(c)  Included in accounts payable and accrued liabilities and other liabilities in the consolidated balance sheets.

Changes in Fair Value of Level 3 Liabilities Representing Acquisition Related Contingent Consideration

The table below sets forth a summary of the changes in fair value of the Company’s Level 3 liabilities as of June 30, 2017 and 2016 that represent contingent consideration related to acquisitions:

(In millions)	2017			2016
Balance at January 1,	$	241		$	309
Additions	34			8
Payments	(65		)	(50		)
Revaluation Impact	(8		)	18
Other (a)	1			(6		)
Balance at June 30,	$	203		$	279

^(a) Primarily reflects the impact of foreign exchange.

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Retirement Benefits (Tables)

6 Months Ended

Jun. 30, 2017

Defined Benefit Plan [Abstract]

Schedule of Net Benefit Costs

The components of the net periodic benefit cost for defined benefit and other post-retirement plans are as follows:

Combined U.S. and significant non-U.S. plans	Pension Benefits						Post-retirement Benefits
For the Three Months Ended June 30,
(In millions)	2017			2016			2017			2016
Service cost	$	19		$	46		$	—		$	—
Interest cost	124			138			1			1
Expected return on plan assets	(230		)	(242		)	—			—
Amortization of prior service cost (credit)	(1		)	(1		)	—			1
Recognized actuarial loss	43			42			—			—
Net periodic benefit (credit) cost	$	(45	)	$	(17	)	$	1		$	2
Curtailment gain	—			(5		)	—			—
Settlement loss	—			1			—			—
Total (credit) cost	$	(45	)	$	(21	)	$	1		$	2
Combined U.S. and significant non-U.S. plans	Pension Benefits						Post-retirement Benefits
For the Six Months Ended June 30,
(In millions)	2017			2016			2017			2016
Service cost	$	37		$	90		$	—		$	—
Interest cost	246			275			2			3
Expected return on plan assets	(454		)	(483		)	—			—
Amortization of prior service cost (credit)	(1		)	(1		)	1			2
Recognized actuarial loss (gain)	83			84			—			(1		)
Net periodic benefit (credit) cost	$	(89	)	$	(35	)	$	3		$	4
Curtailment gain	(1		)	(5		)	—			—
Settlement loss	1			1			—			—
Total (credit) cost	$	(89	)	$	(39	)	$	3		$	4
U.S. Plans only	Pension Benefits						Post-retirement Benefits
For the Three Months Ended June 30,
(In millions)	2017			2016			2017			2016
Service cost	$	—		$	27		$	—		$	—
Interest cost	66			66			1			—
Expected return on plan assets	(90		)	(95		)	—			—
Amortization of prior service cost	—			—			1			1
Recognized actuarial loss (gain)	10			18			(1		)	—
Net periodic benefit (credit) cost	$	(14	)	$	16		$	1		$	1

U.S. Plans only	Pension Benefits						Post-retirement Benefits
For the Six Months Ended June 30,
(In millions)	2017			2016			2017			2016
Service cost	$	—		$	53		$	—		$	—
Interest cost	132			132			1			1
Expected return on plan assets	(179		)	(190		)	—			—
Amortization of prior service cost	—			—			2			2
Recognized actuarial loss (gain)	19			36			(1		)	(1		)
Net periodic benefit (credit) cost	$	(28	)	$	31		$	2		$	2

Significant non-U.S. plans only	Pension Benefits						Post-retirement Benefits
For the Three Months Ended June 30,
(In millions)	2017			2016			2017			2016
Service cost	$	19		$	19		$	—		$	—
Interest cost	58			72			—			1
Expected return on plan assets	(140		)	(147		)	—			—
Amortization of prior service credit	(1		)	(1		)	(1		)	—
Recognized actuarial loss	33			24			1			—
Net periodic benefit (credit) cost	$	(31	)	$	(33	)	$	—		$	1
Curtailment gain	—			(5		)	—			—
Settlement loss	—			1			—			—
Total (credit) cost	$	(31	)	$	(37	)	$	—		$	1

Significant non-U.S. plans only	Pension Benefits						Post-retirement Benefits
For the Six Months Ended June 30,
(In millions)	2017			2016			2017			2016
Service cost	$	37		$	37		$	—		$	—
Interest cost	114			143			1			2
Expected return on plan assets	(275		)	(293		)	—			—
Amortization of prior service credit	(1		)	(1		)	(1		)	—
Recognized actuarial loss	64			48			1			—
Net periodic benefit (credit) cost	$	(61	)	$	(66	)	$	1		$	2
Curtailment gain	(1		)	(5		)	—			—
Settlement loss	1			1			—			—
Total (credit) cost	$	(61	)	$	(70	)	$	1		$	2

Schedule of Assumptions Used

The weighted average actuarial assumptions utilized to calculate the net periodic benefit costs for the U.S. and significant non-U.S. defined benefit plans are as follows:

Combined U.S. and significant non-U.S. plans	Pension Benefits				Post-retirement Benefits
June 30,	2017		2016		2017		2016
Weighted average assumptions:
Expected return on plan assets	6.64	%	7.07	%	—		—
Discount rate	3.40	%	4.11	%	3.64	%	4.12	%
Rate of compensation increase*	1.77	%	2.44	%	—		—

*The 2017 assumption does not include a rate of compensation increase for the U.S. defined benefit plans since future benefit accruals were discontinued for those plans after December 31, 2016.

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Debt (Tables)

6 Months Ended

Jun. 30, 2017

Debt Disclosure [Abstract]

Schedule of Outstanding Debt

The Company’s outstanding debt is as follows:

(In millions)	June 30, 2017		December 31, 2016
Short-term:
Commercial paper	$	150	$	50
Current portion of long-term debt	12		262
	162		312
Long-term:
Senior notes – 2.30% due 2017	—		250
Senior notes – 2.55% due 2018	249		249
Senior notes – 2.35% due 2019	299		299
Senior notes – 2.35% due 2020	498		497
Senior notes – 4.80% due 2021	498		498
Senior notes – 2.75% due 2022	496		—
Senior notes – 3.30% due 2023	347		347
Senior notes – 4.05% due 2023	248		248
Senior notes – 3.50% due 2024	596		596
Senior notes – 3.50% due 2025	496		495
Senior notes – 3.75% due 2026	596		596
Senior notes – 5.875% due 2033	297		297
Senior notes – 4.35% due 2047	492		—
Mortgage – 5.70% due 2035	376		382
Other	3		3
	5,491		4,757
Less current portion	12		262
	$	5,479	$	4,495

Estimated Fair Value Of Significant Financial Instruments

The estimated fair value of the Company’s short-term and long-term debt is provided below. Certain estimates and judgments were required to develop the fair value amounts. The fair value amounts shown below are not necessarily indicative of the amounts that the Company would realize upon disposition, nor do they indicate the Company’s intent or need to dispose of the financial instrument.

	June 30, 2017				December 31, 2016
(In millions)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Short-term debt	$	162	$	162	$	312	$	313
Long-term debt	$	5,479	$	5,714	$	4,495	$	4,625

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Restructuring Costs (Tables)

6 Months Ended

Jun. 30, 2017

Restructuring and Related Activities [Abstract]

Restructuring Activities

Details of the restructuring activity from January 1, 2016 through June 30, 2017, which includes liabilities from actions prior to 2017, are as follows:

(In millions)	Liability at 1/1/16		Amounts Accrued		Cash Paid			Other			Liability at 12/31/16		Amounts Accrued		Cash Paid			Other			Liability at 6/30/17
Severance	$	15	$	40	$	(22	)	$	(1	)	$	32	$	19	$	(30	)	$	(2	)	$	19
Future rent under non-cancelable leases and other costs	78		4		(17		)	(4		)	61		5		(9		)	(2		)	55
Total	$	93	$	44	$	(39	)	$	(5	)	$	93	$	24	$	(39	)	$	(4	)	$	74

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Segment Information (Tables)

6 Months Ended

Jun. 30, 2017

Segment Reporting [Abstract]

Selected Information And Details For MMC's Operating Segments

Selected information about the Company’s operating segments for the three and six-month periods ended June 30, 2017 and 2016 are as follows:

	Three Months Ended June 30,							Six Months Ended June 30,
(In millions)	Revenue				Operating Income (Loss)			Revenue				Operating Income (Loss)
2017–
Risk and Insurance Services	$	1,916		(a)	$	528		$	3,905		(c)	$	1,141
Consulting	1,592			(b)	283			3,118			(d)	524
Total Operating Segments	3,508				811			7,023				1,665
Corporate / Eliminations	(13		)		(47		)	(25		)		(92		)
Total Consolidated	$	3,495			$	764		$	6,998			$	1,573
2016–
Risk and Insurance Services	$	1,850		(a)	$	490		$	3,718		(c)	$	1,025
Consulting	1,539			(b)	285			3,017			(d)	530
Total Operating Segments	3,389				775			6,735				1,555
Corporate / Eliminations	(13		)		(49		)	(23		)		(96		)
Total Consolidated	$	3,376			$	726		$	6,712			$	1,459

^(a)  Includes inter-segment revenue of $4 million and $3 million in 2017and2016, respectively, interest income on fiduciary funds of $9 million and $6 million in 2017 and 2016, respectively, and equity method income of $7 million and $6 million in 2017 and 2016, respectively.

^(b)  Includes inter-segment revenue of $9 million and $10 million in 2017 and 2016, respectively, interest income on fiduciary funds of less than $1 million in both 2017 and 2016, and equity method income of $5 million in both 2017 and 2016.

^(c)  Includes inter-segment revenue of $4 million in both 2017 and 2016, interest income on fiduciary funds of $17 million and $12 million in 2017 and 2016, respectively, and equity method income of $9 million and $7 million in 2017 and 2016, respectively.

^(d)  Includes inter-segment revenue of $21 million and $19 million in 2017 and 2016, respectively, interest income on fiduciary funds of $1 million in both 2017 and 2016, and equity method income of $9 million in both 2017 and 2016.

Details of Operating Segment Revenue

Details of operating segment revenue for the three and six month period ended June 30, 2017 and 2016 are as follows:

	Three Months Ended June 30,						Six Months Ended June 30,
(In millions)	2017			2016			2017			2016
Risk and Insurance Services
Marsh	$	1,621		$	1,564		$	3,223		$	3,057
Guy Carpenter	295			286			682			661
Total Risk and Insurance Services	1,916			1,850			3,905			3,718
Consulting
Mercer	1,109			1,079			2,186			2,118
Oliver Wyman Group	483			460			932			899
Total Consulting	1,592			1,539			3,118			3,017
Total Operating Segments	3,508			3,389			7,023			6,735
Corporate / Eliminations	(13		)	(13		)	(25		)	(23		)
Total	$	3,495		$	3,376		$	6,998		$	6,712

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Nature of Operations (Details) $ in Billions	6 Months Ended
	Jun. 30, 2017 USD ($) segment
Segment Reporting Information [Line Items]
Number of business segments | segment	2
Mercer Consulting Group
Segment Reporting Information [Line Items]
Assets under management | $	$ 191

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Principles of Consolidation And Other Matters (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Operating funds related to regulatory requirements or as collateral under captive insurance arrangements	$ 172,000,000		$ 172,000,000
Equity method investments lag period			3 months
Investment income (loss)	$ 5,000,000	$ 1,000,000	$ 5,000,000	$ (2,000,000)
Effective tax rate (as a percent)	28.60%	29.50%	25.90%	29.00%
Unrecognized tax benefits	$ 66,000,000		$ 66,000,000		$ 65,000,000
Minimum
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Reasonably possible decrease in unrecognized tax benefits	0		0
Maximum
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Reasonably possible decrease in unrecognized tax benefits	$ 9,000,000		$ 9,000,000

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Fiduciary Assets and Liabilities (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Fiduciary Assets and Liabilities [Line Items]
Net uncollected premiums and claims receivable and payable	$ 7,700		$ 7,700		$ 7,000
Operating Segments | Risk and Insurance Services Segment
Fiduciary Assets and Liabilities [Line Items]
Interest on fiduciary funds (less than)	9	$ 6	17	$ 12
Operating Segments | Consulting Segment
Fiduciary Assets and Liabilities [Line Items]
Interest on fiduciary funds (less than)	$ 1	$ 1	$ 1	$ 1

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Per Share Data (Basic and Diluted EPS Calculation Continuing Operations) (Details) - $ / shares shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share [Abstract]
Basic weighted average common shares outstanding (in shares)	514.0	521.0	514.0	521.0
Dilutive effect of potentially issuable common shares (in shares)	6.0	4.0	7.0	5.0
Diluted weighted average common shares outstanding (in shares)	520.0	525.0	521.0	526.0
Average stock price used to calculate common stock equivalents (in dollars per share)	$ 75.41	$ 64.17	$ 73.36	$ 60.01
Stock options outstanding (in shares)	12.4	13.9	12.4	13.9

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Supplemental Disclosures to the Consolidated Statements of Cash Flows (Additional Information Concerning Acquisitions, Interest And Income Taxes Paid) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Supplemental Cash Flow Information [Abstract]
Assets acquired, excluding cash	$ 576	$ 107
Liabilities assumed	(74)	(4)
Contingent/deferred purchase consideration	(90)	(26)
Net cash outflow for acquisitions	412	77
Interest paid	92	86
Income taxes paid, net of refunds	$ 297	$ 303

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Supplemental Disclosures to the Consolidated Statements of Cash Flows (Narrative) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Supplemental Disclosure to the Consolidate Statements of Cash Flows [Line Items]
Deferred and contingent consideration from prior years acquisition	$ 97	$ 63
Contingent consideration from prior year's acquisitions	60	24
Net charge for adjustments related to acquisition related accounts	(8)	18
Payment of contingent consideration	5	26
Non-cash issuance of common stock	87	70
Stock-based compensation expense, equity awards	75	58
Effective income tax rate reconciliation, share-based compensation, excess tax benefit, amount	(48)
Adjustments to additional paid in capital, income tax benefit from share-based compensation		24
Excess tax benefit from share-based compensation, financing activities		24
Prior Fiscal Periods Acquisitions
Supplemental Disclosure to the Consolidate Statements of Cash Flows [Line Items]
Deferred purchase consideration from prior years' acquisitions	37	39
Contingent consideration from prior year's acquisitions	$ 65	$ 50

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Other Comprehensive Income (Loss) (Schedule of Components of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss), net of tax	$ 296	$ (204)	$ 552	$ (81)
Unrealized Investment Gains
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	16	6	19	6
Other comprehensive income (loss) before reclassifications	14	0	11	0
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Other comprehensive income (loss), net of tax	14	0	11	0
Balance, ending of period	30	6	30	6
Pension/Postretirement Plans Gains (Losses)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(3,208)	(3,014)	(3,232)	(3,124)
Other comprehensive income (loss) before reclassifications	(40)	98	(46)	178
Amounts reclassified from accumulated other comprehensive income	33	31	63	61
Other comprehensive income (loss), net of tax	(7)	129	17	239
Balance, ending of period	(3,215)	(2,885)	(3,215)	(2,885)
Foreign Currency Translation Gains (Losses)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(1,645)	(1,089)	(1,880)	(1,102)
Other comprehensive income (loss) before reclassifications	289	(333)	524	(320)
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Other comprehensive income (loss), net of tax	289	(333)	524	(320)
Balance, ending of period	(1,356)	(1,422)	(1,356)	(1,422)
AOCI Attributable to Parent
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(4,837)	(4,097)	(5,093)	(4,220)
Other comprehensive income (loss) before reclassifications	263	(235)	489	(142)
Amounts reclassified from accumulated other comprehensive income	33	31	63	61
Other comprehensive income (loss), net of tax	296	(204)	552	(81)
Balance, ending of period	$ (4,541)	$ (4,301)	$ (4,541)	$ (4,301)

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Other Comprehensive Income (Loss) (Schedule Of Components Of Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Equity [Abstract]
Foreign currency translation adjustments, Pre-Tax		$ 290	$ (334)	$ 525	$ (321)
Foreign currency translation adjustments, Tax		1	(1)	1	(1)
Foreign currency translation adjustments, Net of Tax		289	(333)	524	(320)
Unrealized investment gains (losses), Pre-Tax		24	0	19	0
Unrealized investment gains (losses), Tax		10	0	8	0
Unrealized investment gains (losses), Net of Tax		14	0	11	0
Pension/post-retirement plans:
Prior services losses (gains), Pre-Tax	[1]			0	1
Prior service losses (gains), Tax	[1]			0	0
Prior Service losses (gains), Net of Tax	[1]			0	1
Net actuarial loss, Pre-Tax	[1]	42	43	82	84
Net actuarial loss, Tax	[1]	9	12	19	24
Net actuarial loss, Net of Tax	[1]	33	31	63	60
Subtotal, Pre-Tax		42	43	82	85
Subtotal, Tax		9	12	19	24
Subtotal, Net of Tax		33	31	63	61
Effect of remeasurement, Pre-tax		0	0	9	(1)
Effect of remeasurement, Tax		1	0	3	0
Effect of remeasurement, Net of Tax		(1)	0	6	(1)
Effect of curtailment, Pre-Tax		0	3	(1)	3
Effect of curtailment, Tax		0	1	0	1
Effect of curtailment, Net of Tax		0	2	(1)	2
Effect of settlement, Pre-tax				1	1
Effect of settlement, Tax				0	0
Effect of settlement, Net of Tax				1	1
Foreign currency translation adjustment, Pre-Tax		(47)	116	(62)	213
Foreign currency translation adjustment, Tax		(8)	21	(11)	37
Foreign currency translation adjustment, Net of Tax		(39)	95	(51)	176
Other, Pre-Tax		0	1	(1)	0
Other, Tax		0	0	0	0
Other, Net of Tax		0	1	(1)	0
Pension/post-retirement plans losses (gains), Pre-Tax		(5)	163	28	301
Pension/post-retirement plans losses (gains), Tax		2	34	11	62
Pension/post-retirement plans losses (gains), Net of Tax		(7)	129	17	239
Other comprehensive income (loss), before tax		309	(171)	572	(20)
Other comprehensive income (loss), Tax		13	33	20	61
Other comprehensive income (loss), net of tax		$ 296	$ (204)	$ 552	$ (81)

[1] Components of net periodic pension cost are included in compensation and benefits in the Consolidated Statements of Income. Tax on prior service gains and net actuarial losses is included in income tax expense.

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Acquisitions (Narrative) (Details) $ in Millions	3 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2017 USD ($) acquisition	Jun. 30, 2016 USD ($)	Dec. 31, 2016 acquisition
Business Acquisition [Line Items]
Total consideration		$ 510	$ 105
Cash		420	79
Estimated fair value of deferred/contingent consideration		90	26
Contingent consideration from prior year's acquisitions		60	24
Current Fiscal Period Acquisitions
Business Acquisition [Line Items]
Total consideration		510
Cash		420
Estimated fair value of deferred/contingent consideration		90
Revenue related to acquisitions	$ 34	63
Operating income related to acquisitions	$ 5	15
Prior Fiscal Periods Acquisitions
Business Acquisition [Line Items]
Deferred purchase consideration from prior years' acquisitions		37	39
Contingent consideration from prior year's acquisitions		$ 65	$ 50
Risk and Insurance Services Segment
Business Acquisition [Line Items]
Number of acquisitions made (in acquisitions) | acquisition		5		9
Consulting Segment
Business Acquisition [Line Items]
Number of acquisitions made (in acquisitions) | acquisition				6
Minimum
Business Acquisition [Line Items]
Revenue target period (in years)		2 years
Minimum | Current Fiscal Period Acquisitions
Business Acquisition [Line Items]
Revenue target period (in years)		2 years
Maximum
Business Acquisition [Line Items]
Revenue target period (in years)		4 years
Maximum | Current Fiscal Period Acquisitions
Business Acquisition [Line Items]
Revenue target period (in years)		4 years

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Acquisitions (Allocation Of Acquisition Costs) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Cash	$ 420	$ 79
Estimated fair value of deferred/contingent consideration	90	26
Total Consideration	510	105
Allocation of purchase price:
Goodwill	8,821	$ 7,945	$ 8,369	$ 7,889
Current Fiscal Period Acquisitions
Business Acquisition [Line Items]
Cash	420
Estimated fair value of deferred/contingent consideration	90
Total Consideration	510
Allocation of purchase price:
Cash and cash equivalents	8
Accounts receivable, net	7
Property, plant, and equipment	3
Other intangible assets	196
Goodwill	370
Total assets acquired	584
Current liabilities	4
Other liabilities	70
Total liabilities assumed	74
Net assets acquired	$ 510

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Acquisitions (Acquired Finite-Lived Intangible Assets) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2017 USD ($)
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired	$ 196
Client relationships
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired	$ 184
Finite-lived intangible assets, remaining amortization period	13 years
Other
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired	$ 12
Finite-lived intangible assets, remaining amortization period	4 years

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Acquisitions (Pro-Forma Information) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Business Combinations [Abstract]
Revenue	$ 3,496	$ 3,493	$ 7,011	$ 6,951
Net income attributable to the Company	$ 502	$ 470	$ 1,072	$ 950
Basic net income per share:
Basic net income per share attributable to the Company (in dollars per share)	$ 0.98	$ 0.90	$ 2.08	$ 1.82
Diluted net income per share:
Diluted net income per share attributable to the Company (in dollars per share)	$ 0.96	$ 0.89	$ 2.06	$ 1.81

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Goodwill and Other Intangibles (Narrative) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Goodwill	$ 8,821	$ 7,945	$ 8,369	$ 7,889
Aggregate amortization expense	80	$ 67
Risk and Insurance Services Segment
Segment Reporting Information [Line Items]
Goodwill	6,300
Consulting Segment
Segment Reporting Information [Line Items]
Goodwill	$ 2,500

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Goodwill and Other Intangibles (Changes in the Carrying Amount of Goodwill) (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016
Goodwill [Roll Forward]
Balance as of January 1, as reported		$ 8,369	$ 7,889
Goodwill acquired		370	62
Other adjustments	[1]	82	(6)
Balance at June 30,		$ 8,821	$ 7,945

[1] (a) The increase in 2017 primarily reflects the impact of foreign exchange.

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Goodwill and Other Intangibles (Amortized Intangible Assets) (Details) - USD ($) $ in Millions		Jun. 30, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Cost		$ 1,779	$ 1,594
Accumulated Amortization		546	468
Net Carrying Amount		1,233	1,126
Client relationships
Finite-Lived Intangible Assets [Line Items]
Gross Cost		1,581	1,390
Accumulated Amortization		453	392
Net Carrying Amount		1,128	998
Other Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Gross Cost	[1]	198	204
Accumulated Amortization	[1]	93	76
Net Carrying Amount	[1]	$ 105	$ 128

[1] Primarily non-compete agreements, trade names and developed technology.

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Goodwill And Other Intangibles (Estimated Future Aggregate Amortization Expense) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
2017 (excludes amortization through June 30, 2017)	$ 85
2018	158
2019	149
2020	127
2021	118
Subsequent years	596
Net Carrying Amount	$ 1,233	$ 1,126

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Fair Value Measurements (Narrative) (Details) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017 USD ($) $ / shares shares	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) $ / shares shares	Jun. 30, 2016 USD ($)	Jun. 30, 2017 ZAR / shares	Jun. 23, 2017 ZAR / shares	Jun. 01, 2017 ZAR / shares	Dec. 31, 2016 USD ($)	Feb. 24, 2015 USD ($)	Dec. 31, 2014 ZAR / shares
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Adjustments to acquisition related contingent consideration liability			$ (8)
Increase in fair value of contingent consideration due to 5% increase in projections			19
Decrease in fair value of contingent consideration due to 5% decrease in projections			22
Carrying value of investment	$ 416		416					$ 389
Unrealized investment gains	24	$ 0	$ 19	$ 0
Minimum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Revenue target period (in years)			2 years
Maximum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Revenue target period (in years)			4 years
Private Equity Funds, Foreign
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value of investment	76		$ 76					$ 79
Alexander Forbes Group Holdings Limited
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Share price (per share amount) | ZAR / shares					ZAR 6.95					ZAR 7.50
Carrying value of investment	$ 275		$ 275
Percentage of ownership in equity investment	33.00%		33.00%
Investment shares owned | shares	443		443
Market value of investment	$ 237		$ 237
Alexander Forbes Group Holdings Limited | Minimum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Share price (per share amount) | ZAR / shares					5.99		ZAR 6.25
Alexander Forbes Group Holdings Limited | Maximum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Share price (per share amount) | ZAR / shares					ZAR 7.95	ZAR 7.31
Benefitfocus
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Market value of investment	$ 102		102
Percentage of business interest acquired									9.90%
Total consideration									$ 75
Unrealized investment gains			$ 19
Money Market Funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Share price (per share amount) | $ / shares	$ 1.00		$ 1.00

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Fair Value Measurements (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Millions		Jun. 30, 2017	Dec. 31, 2016
Financial instruments owned:
Total assets measured at fair value		$ 283	$ 252
Fiduciary Assets:
Fiduciary assets		82	90
Liabilities:
Total liabilities measured at fair value		203	241
Identical Assets (Level 1)
Financial instruments owned:
Total assets measured at fair value		283	252
Fiduciary Assets:
Fiduciary assets		82	90
Liabilities:
Total liabilities measured at fair value		0	0
Observable Inputs (Level 2)
Financial instruments owned:
Total assets measured at fair value		0	0
Fiduciary Assets:
Fiduciary assets		0	0
Liabilities:
Total liabilities measured at fair value		0	0
Unobservable Inputs (Level 3)
Financial instruments owned:
Total assets measured at fair value		0	0
Fiduciary Assets:
Fiduciary assets		0	0
Liabilities:
Total liabilities measured at fair value		203	241
Money Market Funds
Fiduciary Assets:
Fiduciary assets		82	90
Money Market Funds | Identical Assets (Level 1)
Fiduciary Assets:
Fiduciary assets		82	90
Money Market Funds | Observable Inputs (Level 2)
Fiduciary Assets:
Fiduciary assets		0	0
Money Market Funds | Unobservable Inputs (Level 3)
Fiduciary Assets:
Fiduciary assets		0	0
Other Assets
Financial instruments owned:
Exchange traded equity securities	[1]	107	89
Mutual funds	[1]	140	141
Other Assets | Identical Assets (Level 1)
Financial instruments owned:
Exchange traded equity securities	[1]	107	89
Mutual funds	[1]	140	141
Other Assets | Observable Inputs (Level 2)
Financial instruments owned:
Exchange traded equity securities	[1]	0	0
Mutual funds	[1]	0	0
Other Assets | Unobservable Inputs (Level 3)
Financial instruments owned:
Exchange traded equity securities	[1]	0	0
Mutual funds	[1]	0	0
Cash and Cash Equivalents
Financial instruments owned:
Money market funds	[2]	36	22
Cash and Cash Equivalents | Identical Assets (Level 1)
Financial instruments owned:
Money market funds	[2]	36	22
Cash and Cash Equivalents | Observable Inputs (Level 2)
Financial instruments owned:
Money market funds	[2]	0	0
Cash and Cash Equivalents | Unobservable Inputs (Level 3)
Financial instruments owned:
Money market funds	[2]	0	0
Accounts Payable and Accrued Liabilities and Other Liabilities
Liabilities:
Contingent purchase consideration liability	[3]	203	241
Accounts Payable and Accrued Liabilities and Other Liabilities | Identical Assets (Level 1)
Liabilities:
Contingent purchase consideration liability	[3]	0	0
Accounts Payable and Accrued Liabilities and Other Liabilities | Observable Inputs (Level 2)
Liabilities:
Contingent purchase consideration liability	[3]	0	0
Accounts Payable and Accrued Liabilities and Other Liabilities | Unobservable Inputs (Level 3)
Liabilities:
Contingent purchase consideration liability	[3]	$ 203	$ 241

[1] Included in other assets in the consolidated balance sheets.

[2] Included in cash and cash equivalents in the consolidated balance sheets.

[3] Included in accounts payable and accrued liabilities and other liabilities in the consolidated balance sheets.

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Fair Value Measurements (Changes In Fair Value Of Level 3 Liabilities Representing Acquisition Related Contingent Consideration) (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Revaluation Impact		$ (8)	$ 18
Contingent Consideration
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,		241	309
Additions		34	8
Payments		(65)	(50)
Revaluation Impact		(8)	18
Other	[1]	1	(6)
Balance at June 30,		$ 203	$ 279

[1] (a) Primarily reflects the impact of foreign exchange.

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Retirement Benefits (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended	6 Months Ended
	Oct. 31, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Employer matching contribution, percent of employees' gross pay (up to)	4.00%
Maximum annual contributions per employee, percent	7.00%
Contributions by employer		$ 120
Defined contribution plan, cost recognized		65	$ 38
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Estimated future employer contributions in current fiscal year		$ 136
United States | Equity Funds
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation U.S. Plan		64.00%
Actual asset allocation percentage of equity		64.00%
United States | Fixed Income Funds
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation U.S. Plan		36.00%
Actual asset allocation percentage of equity		36.00%
United Kingdom | Equity Funds
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation U.S. Plan				46.00%
Actual asset allocation percentage of equity		46.00%
United Kingdom | Fixed Income Funds
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation U.S. Plan				54.00%
Actual asset allocation percentage of equity		54.00%
United Kingdom | Geographic Concentration Risk | Non-U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Concentration risk percentage		81.00%

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Retirement Benefits (Schedule Of Defined Benefit Plan Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 19	$ 46	$ 37	$ 90
Interest cost	124	138	246	275
Expected return on plan assets	(230)	(242)	(454)	(483)
Amortization of prior service cost (credit)	(1)	(1)	(1)	(1)
Recognized actuarial loss (gain)	43	42	83	84
Net periodic benefit (credit) cost	(45)	(17)	(89)	(35)
Curtailment gain (loss)	0	(5)	(1)	(5)
Settlement loss	0	1	1	1
Total (credit) cost	(45)	(21)	(89)	(39)
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0	0
Interest cost	1	1	2	3
Expected return on plan assets	0	0	0	0
Amortization of prior service cost (credit)	0	1	1	2
Recognized actuarial loss (gain)	0	0	0	(1)
Net periodic benefit (credit) cost	1	2	3	4
Curtailment gain (loss)	0	0	0	0
Settlement loss	0	0	0	0
Total (credit) cost	1	2	3	4
Domestic Plan | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	27	0	53
Interest cost	66	66	132	132
Expected return on plan assets	(90)	(95)	(179)	(190)
Amortization of prior service cost (credit)	0	0	0	0
Recognized actuarial loss (gain)	10	18	19	36
Net periodic benefit (credit) cost	(14)	16	(28)	31
Domestic Plan | Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0	0
Interest cost	1	0	1	1
Expected return on plan assets	0	0	0	0
Amortization of prior service cost (credit)	1	1	2	2
Recognized actuarial loss (gain)	(1)	0	(1)	(1)
Net periodic benefit (credit) cost	1	1	2	2
Foreign Plan | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	19	19	37	37
Interest cost	58	72	114	143
Expected return on plan assets	(140)	(147)	(275)	(293)
Amortization of prior service cost (credit)	(1)	(1)	(1)	(1)
Recognized actuarial loss (gain)	33	24	64	48
Net periodic benefit (credit) cost	(31)	(33)	(61)	(66)
Curtailment gain (loss)	0	(5)	(1)	(5)
Settlement loss	0	1	1	1
Total (credit) cost	(31)	(37)	(61)	(70)
Foreign Plan | Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0	0
Interest cost	0	1	1	2
Expected return on plan assets	0	0	0	0
Amortization of prior service cost (credit)	(1)	0	(1)	0
Recognized actuarial loss (gain)	1	0	1	0
Net periodic benefit (credit) cost	0	1	1	2
Curtailment gain (loss)	0	0	0	0
Settlement loss	0	0	0	0
Total (credit) cost	$ 0	$ 1	$ 1	$ 2

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Retirement Benefits (Schedule Of Defined Benefit Plan Weighted Average Assumption Used In Calculating Net Periodic Benefit Cost) (Details)		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016
Pension Benefits
Weighted average assumptions:
Expected return on plan assets		6.64%	7.07%
Discount rate		3.40%	4.11%
Rate of compensation increase	[1]	1.77%	2.44%
Postretirement Benefits
Weighted average assumptions:
Expected return on plan assets		0.00%	0.00%
Discount rate		3.64%	4.12%
Rate of compensation increase	[1]	0.00%	0.00%

[1] *The 2017 assumption does not include a rate of compensation increase for the U.S. defined benefit plans since future benefit accruals were discontinued for those plans after December 31, 2016.

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Debt (Schedule Of Outstanding Debt) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Jan. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Debt Instrument [Line Items]
Commercial paper outstanding	$ 150		$ 50
Current portion of long-term debt	12		262
Short-term debt	162		312
Long-term debt, current and noncurrent	5,491		4,757
Long-term debt	5,479		4,495
2.30% Senior Debt Obligations Due 2017
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 0		250
Interest rate	2.30%
2.55% Senior Debt Obligations Due 2018
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 249		249
Interest rate	2.55%
2.35% Senior Debt Obligations Due 2019
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 299		299
Interest rate	2.35%
2.35% Senior Debt Obligations Due 2020
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 498		497
Interest rate	2.35%
4.80% Senior Debt Obligations Due 2021
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 498		498
Interest rate	4.80%
2.75% Senior Debt Obligations Due 2022
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 496		0
Interest rate	2.75%	2.75%
3.30% Senior Debt Obligations Due 2023
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 347		347
Interest rate	3.30%			3.30%
4.05% Senior Debt Obligations Due 2023
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 248		248
Interest rate	4.05%
3.50% Senior Debt Obligations Due 2024
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 596		596
Interest rate	3.50%
3.50% Senior Debt Obligations Due 2025
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 496		495
Interest rate	3.50%
3.75% Senior Debt Obligations Due 2026
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 596		596
Interest rate	3.75%
5.875% Senior Debt Obligations Due 2033
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 297		297
Interest rate	5.875%
4.35% Senior Debt Obligation Due 2047
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 492		0
Interest rate	4.35%	4.35%
Mortgage Due 2035
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 376		382
Interest rate	5.70%
Other
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 3		$ 3

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Debt (Narrative) (Details) - USD ($)	1 Months Ended		6 Months Ended
	Apr. 30, 2017	Mar. 31, 2016	Jun. 30, 2017	Jan. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Commercial paper outstanding			$ 150,000,000		$ 50,000,000
Repayments of senior debt	$ 250,000,000
2.75% Senior Debt Obligations Due 2022
Debt Instrument [Line Items]
Interest rate			2.75%	2.75%
Proceeds from issuance of debt				$ 500,000,000
4.35% Senior Debt Obligation Due 2047
Debt Instrument [Line Items]
Interest rate			4.35%	4.35%
Proceeds from issuance of debt				$ 500,000,000
3.30% Senior Debt Obligations Due 2023
Debt Instrument [Line Items]
Interest rate		3.30%	3.30%
Proceeds from issuance of debt		$ 350,000,000
Term of debt		7 years
Amended Revolving Credit Facility March 27, 2014
Debt Instrument [Line Items]
Term of debt			5 years
Debt facilities, maximum borrowing capacity			$ 1,500,000,000
Revolving credit facility, amount outstanding			0
Commercial Paper
Debt Instrument [Line Items]
Borrowings under uncommited bank credit line			$ 1,500,000,000
Interest rate			1.45%

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Debt (Estimated Fair Value of Significant Financial Instruments) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term debt	$ 162	$ 312
Long-term debt	5,479	4,495
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term debt	162	313
Long-term debt	$ 5,714	$ 4,625

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Restructuring Costs (Restructuring Activities) (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Restructuring Reserve [Roll Forward]
Liability at beginning of period	$ 93	$ 93
Amounts Accrued	24	44
Cash Paid	(39)	(39)
Other	(4)	(5)
Liability at end of period	74	93
Severance
Restructuring Reserve [Roll Forward]
Liability at beginning of period	32	15
Amounts Accrued	19	40
Cash Paid	(30)	(22)
Other	(2)	(1)
Liability at end of period	19	32
Future rent under non-cancelable leases and other costs
Restructuring Reserve [Roll Forward]
Liability at beginning of period	61	78
Amounts Accrued	5	4
Cash Paid	(9)	(17)
Other	(2)	(4)
Liability at end of period	55	$ 61
Operating Segments | Risk and Insurance Services Segment | Acquisition Related
Restructuring Reserve [Roll Forward]
Amounts Accrued	4
Operating Segments | Consulting Segment | Acquisition Related
Restructuring Reserve [Roll Forward]
Amounts Accrued	16
Corporate | Acquisition Related
Restructuring Reserve [Roll Forward]
Amounts Accrued	$ 4

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Common Stock (Details) - USD ($) shares in Millions, $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Nov. 30, 2016
Equity, Class of Treasury Stock [Line Items]
Payments for repurchase of common stock	$ 400	$ 410
Stock-based compensation, shares issued during period	3.7	4.1
Common Stock
Equity, Class of Treasury Stock [Line Items]
Common stock repurchased (in shares)	5.4	7.0
Payments for repurchase of common stock	$ 400	$ 425
Share repurchases program, authorized amount (up to)			$ 2,500
Stock repurchase program, remaining authorized repurchase amount	$ 2,000

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Claims, Lawsuits And Other Contingencies (Details) £ in Millions	Jun. 30, 2017 GBP (£)
Other Contingencies-Guarantees
Loss Contingencies [Line Items]
Amount reinsured by third party (up to)	£ 40

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Segment Information (Selected Information And Details For MMC's Operating Segments) (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2017		Jun. 30, 2016		Jun. 30, 2017		Jun. 30, 2016
Segment Reporting Information [Line Items]
Revenue	$ 3,495		$ 3,376		$ 6,998		$ 6,712
Operating Income (Loss)	764		726		1,573		1,459
Operating Segments
Segment Reporting Information [Line Items]
Revenue	3,508		3,389		7,023		6,735
Operating Income (Loss)	811		775		1,665		1,555
Operating Segments | Risk and Insurance Services Segment
Segment Reporting Information [Line Items]
Revenue	1,916	[1]	1,850	[1]	3,905	[2]	3,718	[2]
Operating Income (Loss)	528		490		1,141		1,025
Interest on fiduciary funds (less than)	9		6		17		12
Equity method income	7		6		9		7
Operating Segments | Consulting Segment
Segment Reporting Information [Line Items]
Revenue	1,592	[3]	1,539	[3]	3,118	[4]	3,017	[4]
Operating Income (Loss)	283		285		524		530
Interest on fiduciary funds (less than)	1		1		1		1
Equity method income	5		5		9		9
Corporate and Eliminations
Segment Reporting Information [Line Items]
Revenue	(13)		(13)		(25)		(23)
Operating Income (Loss)	(47)		(49)		(92)		(96)
Intersegment Eliminations | Risk and Insurance Services Segment
Segment Reporting Information [Line Items]
Revenue	4		3		4		4
Intersegment Eliminations | Consulting Segment
Segment Reporting Information [Line Items]
Revenue	$ 9		$ 10		$ 21		$ 19

[1] Includes inter-segment revenue of $4 million and $3 million in 2017 and 2016, respectively, interest income on fiduciary funds of $9 million and $6 million in 2017 and 2016, respectively, and equity method income of $7 million and $6 million in 2017 and 2016, respectively.

[2] Includes inter-segment revenue of $4 million in both 2017 and 2016, interest income on fiduciary funds of $17 million and $12 million in 2017 and 2016, respectively, and equity method income of $9 million and $7 million in 2017 and 2016, respectively.

[3] Includes inter-segment revenue of $9 million and $10 million in 2017 and 2016, respectively, interest income on fiduciary funds of less than $1 million in both 2017 and 2016, and equity method income of $5 million in both 2017 and 2016.

[4] Includes inter-segment revenue of $21 million and $19 million in 2017 and 2016, respectively, interest income on fiduciary funds of $1 million in both 2017 and 2016, and equity method income of $9 million in both 2017 and 2016.

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Segment Information (Details of Operating Segment Revenue) (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2017		Jun. 30, 2016		Jun. 30, 2017		Jun. 30, 2016
Segment Reporting Information [Line Items]
Revenue	$ 3,495		$ 3,376		$ 6,998		$ 6,712
Operating Segments
Segment Reporting Information [Line Items]
Revenue	3,508		3,389		7,023		6,735
Operating Segments | Risk and Insurance Services Segment
Segment Reporting Information [Line Items]
Revenue	1,916	[1]	1,850	[1]	3,905	[2]	3,718	[2]
Operating Segments | Risk and Insurance Services Segment | Marsh Insurance Group
Segment Reporting Information [Line Items]
Revenue	1,621		1,564		3,223		3,057
Operating Segments | Risk and Insurance Services Segment | Guy Carpenter Reinsurance Group
Segment Reporting Information [Line Items]
Revenue	295		286		682		661
Operating Segments | Consulting Segment
Segment Reporting Information [Line Items]
Revenue	1,592	[3]	1,539	[3]	3,118	[4]	3,017	[4]
Operating Segments | Consulting Segment | Mercer Consulting Group
Segment Reporting Information [Line Items]
Revenue	1,109		1,079		2,186		2,118
Operating Segments | Consulting Segment | Oliver Wyman Group Consulting Group
Segment Reporting Information [Line Items]
Revenue	483		460		932		899
Corporate and Eliminations
Segment Reporting Information [Line Items]
Revenue	$ (13)		$ (13)		$ (25)		$ (23)

[1] Includes inter-segment revenue of $4 million and $3 million in 2017 and 2016, respectively, interest income on fiduciary funds of $9 million and $6 million in 2017 and 2016, respectively, and equity method income of $7 million and $6 million in 2017 and 2016, respectively.

[2] Includes inter-segment revenue of $4 million in both 2017 and 2016, interest income on fiduciary funds of $17 million and $12 million in 2017 and 2016, respectively, and equity method income of $9 million and $7 million in 2017 and 2016, respectively.

[3] Includes inter-segment revenue of $9 million and $10 million in 2017 and 2016, respectively, interest income on fiduciary funds of less than $1 million in both 2017 and 2016, and equity method income of $5 million in both 2017 and 2016.

[4] Includes inter-segment revenue of $21 million and $19 million in 2017 and 2016, respectively, interest income on fiduciary funds of $1 million in both 2017 and 2016, and equity method income of $9 million in both 2017 and 2016.

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New Accounting Guidance - Narrative (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Effective income tax rate reconciliation, share-based compensation, excess tax benefit, amount	$ (48)
Adjustments to additional paid in capital, income tax benefit from share-based compensation		$ 24
Excess tax benefit from share-based compensation, financing activities		$ 24