Aon (AON) 10-Q 29 Apr 16 2016 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2016	Apr. 21, 2016
Document and Entity Information
Entity Registrant Name	Aon plc
Entity Central Index Key	315,293
Document Type	10-Q
Document Period End Date	Mar. 31, 2016
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		264,918,514
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q1

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Revenue
Commissions, fees and other	$ 2,787	$ 2,842
Fiduciary investment income	5	5
Total revenue	2,792	2,847
Expenses
Compensation and benefits	1,649	1,683
Other general expenses	693	723
Total operating expenses	2,342	2,406
Operating income	450	441
Interest income	2	3
Interest expense	(69)	(65)
Other income	18	42
Income before income taxes	401	421
Income taxes	74	80
Net income	327	341
Less: Net income attributable to noncontrolling interests	12	13
Net income attributable to Aon shareholders	$ 315	$ 328
Basic net income per share attributable to Aon shareholders (in dollars per share)	$ 1.16	$ 1.15
Diluted net income per share attributable to Aon shareholders (in dollars per share)	1.15	1.14
Cash dividends per share paid on ordinary shares (in dollars per share)	$ 0.30	$ 0.25
Weighted average ordinary shares outstanding - basic (in shares)	271.7	284.2
Weighted average ordinary shares outstanding - diluted (in shares)	273.7	287.1

Condensed Consolidated Stateme3

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 327	$ 341
Less: Net income attributable to noncontrolling interests	12	13
Net income attributable to Aon shareholders	315	328
Other comprehensive (loss) income, net of tax:
Change in fair value of financial instruments	(7)	5
Foreign currency translation adjustments	(79)	(322)
Post-retirement benefit obligation	(201)	23
Total other comprehensive (loss)	(287)	(294)
Less: Other comprehensive (loss) income attributable to noncontrolling interests	0	(1)
Total other comprehensive (loss) attributable to Aon shareholders	(287)	(293)
Comprehensive income attributable to Aon shareholders	$ 28	$ 35

Condensed Consolidated Stateme4

Condensed Consolidated Statements of Financial Position (Unaudited) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
CURRENT ASSETS
Cash and cash equivalents	$ 465	$ 384
Short-term investments	587	356
Receivables, net	2,591	2,734
Fiduciary assets	9,776	9,932
Other current assets	622	562
Total Current Assets	14,041	13,968
Goodwill	8,411	8,448
Intangible assets, net	2,108	2,180
Fixed assets, net	766	765
Non-current deferred tax assets	171	141
Prepaid pension	737	1,033
Other non-current assets	579	592
TOTAL ASSETS	26,813	27,127
CURRENT LIABILITIES
Accounts payable and accrued liabilities	1,420	1,772
Short-term debt and current portion of long-term debt	695	562
Fiduciary liabilities	9,776	9,932
Other current liabilities	902	820
Total Current Liabilities	12,793	13,086
Long-term debt	5,902	5,138
Non-current deferred tax liabilities	177	176
Pension, other post-retirement and post-employment liabilities	1,756	1,795
Other non-current liabilities	838	769
TOTAL LIABILITIES	21,466	20,964
EQUITY
Ordinary shares - $0.01 nominal value Authorized: 750 shares (issued: 2016 - 264.8; 2015 - 269.8)	3	3
Additional paid-in capital	5,388	5,409
Retained earnings	3,600	4,117
Accumulated other comprehensive loss	(3,710)	(3,423)
TOTAL AON SHAREHOLDERS' EQUITY	5,281	6,106
Noncontrolling interests	66	57
TOTAL EQUITY	5,347	6,163
TOTAL LIABILITIES AND EQUITY	$ 26,813	$ 27,127

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Financial Position (Unaudited) (Parenthetical) - $ / shares	Mar. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Common stock, nominal or par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, Authorized shares	750,000,000	750,000,000
Common stock, issued shares	264,800,000	269,800,000

Condensed Consolidated Stateme6

Condensed Consolidated Statement of Shareholders' Equity (Unaudited) - 3 months ended Mar. 31, 2016 - USD ($) shares in Millions, $ in Millions	Total	Ordinary Shares and Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated OtherComprehensiveLoss, Net of Tax [Member]	Non-controlling Interests [Member]
Beginning Balance (in shares) at Dec. 31, 2015	269.8	269.8
Beginning Balance at Dec. 31, 2015	$ 6,163	$ 5,412	$ 4,117	$ (3,423)	$ 57
Increase (Decrease) in Shareholders' Equity
Net income	327		315		12
Shares issued - employee benefit plans (in shares)		0.3
Shares issued - employee benefit plans	18	$ 18
Shares issued - employee compensation (in shares)		2.4
Shares issued - employee compensation	(123)	$ (123)
Shares purchased (in shares)		(7.7)
Shares purchased	(750)		(750)
Tax benefit - employee benefit plans	40	$ 40
Share-based compensation expense	85	85
Dividends to shareholders	(82)		(82)
Net change in fair value of financial instruments	(7)			(7)
Net foreign currency translation adjustments	(79)			(79)
Net post-retirement benefit obligation	(201)			(201)
Purchases of shares from noncontrolling interests	$ (44)	$ (41)			(3)
Ending Balance (in shares) at Mar. 31, 2016	264.8	264.8
Ending Balance at Mar. 31, 2016	$ 5,347	$ 5,391	$ 3,600	$ (3,710)	$ 66

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 327	$ 341
Adjustments to reconcile net income to cash provided by operating activities:
Gain from sales of businesses and investments, net	(35)	(19)
Depreciation of fixed assets	56	56
Amortization of intangible assets	67	80
Share-based compensation expense	85	90
Deferred income taxes	23	7
Change in assets and liabilities:
Fiduciary receivables	399	173
Short-term investments — funds held on behalf of clients	(285)	63
Fiduciary liabilities	(114)	(236)
Receivables, net	110	49
Accounts payable and accrued liabilities	(348)	(348)
Current income taxes	(31)	27
Pension, other post-retirement and other post-employment liabilities	(50)	(66)
Other assets and liabilities	69	81
CASH PROVIDED BY OPERATING ACTIVITIES	273	298
CASH FLOWS FROM INVESTING ACTIVITIES
Proceeds from investments	13	3
Purchases of investments	(14)	(1)
Net (purchases) sales of short-term investments — non-fiduciary	(227)	42
Acquisition of businesses, net of cash acquired	(16)	(21)
Proceeds from sale of businesses	97	41
Capital expenditures	(52)	(62)
CASH (USED FOR) PROVIDED BY INVESTING ACTIVITIES	(199)	2
CASH FLOWS FROM FINANCING ACTIVITIES
Share repurchase	(685)	(250)
Issuance of shares for employee benefit plans	(65)	(114)
Issuance of debt	1,045	870
Repayment of debt	(175)	(686)
Cash dividends to shareholders	(82)	(71)
Noncontrolling interests and other financing activities	(42)	(6)
CASH USED FOR FINANCING ACTIVITIES	(4)	(257)
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	11	(39)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	81	4
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	384	374
CASH AND CASH EQUIVALENTS AT END OF PERIOD	465	378
Supplemental disclosures:
Interest paid	52	63
Income taxes paid, net of refunds	$ 41	$ 46

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited Condensed Consolidated Financial Statements and Notes thereto have been prepared in accordance with U.S. generally accepted accounting principles ("U.S. GAAP"). The Condensed Consolidated Financial Statements include the accounts of Aon plc and all of its controlled subsidiaries ("Aon" or the "Company"). All intercompany accounts and transactions have been eliminated. The Condensed Consolidated Financial Statements include, in the opinion of management, all adjustments (consisting of normal recurring adjustments and reclassifications) necessary to present fairly the Company's consolidated financial position, results of operations and cash flows for all periods presented. Certain information and disclosures normally included in the financial statements prepared in accordance with U.S. GAAP have been condensed or omitted. These Condensed Consolidated Financial Statements should be read in conjunction with the Consolidated Financial Statements and Notes thereto included in the Company's Annual Report on Form 10-K for the year ended December 31, 2015 . The results for the three months ended March 31, 2016 are not necessarily indicative of operating results that may be expected for the full year ending December 31, 2016 . Reclassification Certain amounts in prior years' Condensed Consolidated Financial Statements and related notes have been reclassified to conform to the 2016 presentation. In prior periods, prepaid pensions were included in Other non-current assets in the Condensed Consolidated Statement of Financial Position. These amounts are now separately disclosed in the Condensed Consolidated Statement of Financial Position. Prepaid pensions were $737 million at March 31, 2016 and $1,033 million at December 31, 2015 . Upon vesting of certain share-based payment arrangements, employees may elect to use a portion of the shares to satisfy tax withholding requirements, in which case Aon makes a payment to the taxing authority on the employee’s behalf and remits the remaining shares to the employee. The Company has historically presented amounts due to taxing authorities within Cash Flows From Operating Activities in the Condensed Consolidated Statements of Cash Flows. The amounts are now included in “Issuance of shares for employee benefit plans” within Cash Flows From Financing Activities. The Company believes this presentation provides greater clarity into the operating and financing activities of the Company as the substance and accounting for these transactions is that of a share repurchase. It also aligns the Company’s presentation to be consistent with industry practice and share-based compensation guidance issued by the Financial Accounting Standards Board ("FASB") in March 2016. Amounts reported in Issuance of shares for employee benefit plans were $128 million and $162 million , respectively, for the three months ended March 31, 2016 and March 31, 2015 . These amounts, which were reclassified from Accounts payable and accrued liabilities and Other assets and liabilities, were $118 million and $44 million for the three months ended March 31, 2015. Changes to the presentation in the Condensed Consolidated Statements of Cash Flows for the three months ended March 31, 2015 were made related to certain line items within financing activities. In 2016, Purchases of shares from noncontrolling interests and Dividends paid to noncontrolling interests have been aggregated in a new line item titled “Noncontrolling interests and other financing activities” within financing activities. The balances held in these line items for the three months ended March 31, 2015 was $(5) million and $(1) million , respectively. In April 2015, the Financial Accounting Standards Board ("FASB") issued new accounting guidance on the presentation of debt issuance costs, which requires debt issuance costs to be presented in the balance sheet as a direct deduction from the associated debt liability. This guidance became effective for Aon in the first quarter of 2016, which required retrospective application to prior year comparable periods. For the year ended December 31, 2015, Aon reclassified $4 million from Other current assets and $33 million from Other non-current assets to Long-term debt on the Condensed Consolidated Statement of Financial Position. In the first quarter, Aon retrospectively adopted FASB's new accounting guidance on consolidations. No material changes were identified upon adoption of this new guidance. Use of Estimates The preparation of the accompanying Condensed Consolidated Financial Statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosures of contingent assets and liabilities at the date of the financial statements, and the reported amounts of reserves and expenses. These estimates and assumptions are based on management's best estimates and judgments. Management evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment. Management believes its estimates to be reasonable given the current facts available. Aon adjusts such estimates and assumptions when facts and circumstances dictate. Illiquid credit markets, volatile equity markets, and foreign currency exchange rate movements increase the uncertainty inherent in such estimates and assumptions. As future events and their effects cannot be determined, among other factors, with precision, actual results could differ significantly from these estimates. Changes in estimates resulting from continuing changes in the economic environment would, if applicable, be reflected in the financial statements in future periods.

Accounting Principles and Pract

Accounting Principles and Practices	3 Months Ended
	Mar. 31, 2016
Accounting Policies [Abstract]
Accounting Principles and Practices	Accounting Principles and Practices New Accounting Pronouncements Revenue Recognition In May 2014, the FASB issued new accounting guidance on revenue from contracts with customers, which, when effective, will supersede nearly all existing revenue recognition guidance under U.S. GAAP. The core principal of the guidance is that an entity should recognize revenue when it transfers 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. The guidance also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. The guidance is effective for the Company in the first quarter of 2018 and early adoption is permitted beginning the first quarter of 2017. The guidance permits two methods of transition upon adoption: full retrospective and modified retrospective. Under the full retrospective method, prior periods would be restated under the new revenue standard, providing a comparable view across all periods presented. Under the modified retrospective method, prior periods would not be restated. Rather, revenues and other disclosures for pre-2018 periods would be provided in the notes to the financial statements as previously reported under the current revenue standard. The impact from the adoption of this guidance on the Company's Condensed Consolidated Financial Statements cannot be determined at this time. The Company is also determining the appropriate method of transition to the guidance, but expects to adopt upon the effective date of January 1, 2018. Presentation of Deferred Taxes In November 2015, the FASB issued new accounting guidance on the balance sheet presentation of deferred taxes, which requires that deferred tax liabilities and assets be classified as non-current. The guidance is effective for Aon in the first quarter of 2017, however, the Company expects to early adopt this guidance in 2016 and retrospectively apply its requirements to all periods presented. The adoption of this guidance is not expected to have a material impact on the Company's Condensed Consolidated Financial Statements. Financial Assets and Liabilities In January 2016, the FASB issued new accounting guidance on recognition and measurement of financial assets and financial liabilities. The amendments in the new guidance make targeted improvements, which include the requirement to measure equity investments with readily determinable fair values at fair value through net income, simplification of the impairment assessment for equity investments without readily determinable fair values, adjustments to existing and additional disclosure requirements, and additional tax considerations. The guidance is effective for the Company in the first quarter of 2018 and early adoption is permitted. The Company is currently evaluating the impact that the standard will have on the Company's Condensed Consolidated Financial Statements. Leases In February 2016, the FASB issued new accounting guidance on leases, which requires lessees to recognize assets and liabilities for most leases. Under the new guidance, a lessee should recognize in the statement of financial position a liability to make lease payments and a right-of-use asset representing its right to use the underlying asset for the lease term. The recognition, measurement, and presentation of expenses and cash flows arising from a lease by a lessee have not significantly changed from currently effective U.S. GAAP. The new standard will be effective for the Company in the first quarter of 2019, with early application permitted. In transition, lessees and lessors are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The modified retrospective approach includes a number of optional practical expedients that entities may elect to apply. These practical expedients relate to the identification and classification of leases that commenced before the effective date, initial direct costs for leases that commenced before the effective date, and the ability to use hindsight in evaluating lessee options to extend or terminate a lease or to purchase the underlying asset. The Company is currently evaluating the impact the standard will have on the Company's Condensed Consolidated Financial Statements, as well as the method of transition and period of adoption. Share-based Compensation In March 2016, the FASB issued new accounting guidance on several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The new guidance requires all excess tax benefits and tax deficiencies to be recognized as income tax expense or benefit in the income statement and treated as discrete items in the reporting period. Further, excess tax benefits are required to be classified along with other income tax cash flows as an operating activity. The guidance is effective for Aon in the first quarter of 2017 and early adoption is permitted. Aon is currently evaluating the impact that the standard will have on the Company's Condensed Consolidated Financial Statements.

Cash and Cash Equivalents and S

Cash and Cash Equivalents and Short-term Investments	3 Months Ended
	Mar. 31, 2016
Cash, Cash Equivalents, and Short-term Investments [Abstract]
Cash and Cash Equivalents and Short-term Investments	Cash and Cash Equivalents and Short-term Investments Cash and cash equivalents include cash balances and all highly liquid debt instruments with initial maturities of three months or less. Short-term investments include certificates of deposit, money market funds and highly liquid debt instruments purchased with initial maturities in excess of three months but less than one year and are carried at amortized cost, respectively, which approximates fair value. At March 31, 2016 , Cash and cash equivalents and Short-term investments were $1,052 million compared to $740 million at December 31, 2015 . Of the total balances, $95 million and $105 million was restricted as to its use at March 31, 2016 and December 31, 2015 , respectively. Included within the March 31, 2016 and December 31, 2015 balances, respectively, were £43.3 million ( $61.2 million at March 31, 2016 exchange rates) and £43.3 million ( $64.6 million at December 31, 2015 exchange rates) of operating funds required to be held by the Company in the U.K. by the Financial Conduct Authority, a U.K.-based regulator, which were included in Short-term investments.

Other Financial Data

Other Financial Data	3 Months Ended
	Mar. 31, 2016
Other Financial Data [Abstract]
Other Financial Data	Other Financial Data Condensed Consolidated Statements of Income Information Other Income Other income consists of the following (in millions): Three months ended March 31, 2016 2015 Foreign currency remeasurement (loss) gain (17 ) 24 Gain on disposal of business 35 19 Equity earnings 2 2 Income (loss) on financial instruments (2 ) (3 ) Total $ 18 $ 42 Condensed Consolidated Statements of Financial Position Information Allowance for Doubtful Accounts An analysis of the allowance for doubtful accounts is as follows (in millions): Three months ended March 31, 2016 2015 Balance at beginning of period $ 58 $ 74 Provision charged to Other general expenses 6 8 Accounts written off, net of recoveries (2 ) (9 ) Foreign currency translation — (3 ) Balance at end of period $ 62 $ 70 Other Current Assets The components of Other current assets are as follows (in millions): March 31, 2016 December 31, 2015 Taxes receivable $ 122 $ 94 Deferred tax assets 232 232 Prepaid expenses 168 130 Deferred project costs 92 92 Other 8 14 Total $ 622 $ 562 Other Non-Current Assets The components of Other non-current assets are as follows (in millions): March 31, 2016 December 31, 2015 Deferred project costs $ 205 $ 210 Investments 131 135 Taxes receivable 81 82 Other 162 165 Total $ 579 $ 592 Other Current Liabilities The components of Other current liabilities are as follows (in millions): March 31, 2016 December 31, 2015 Deferred revenue $ 438 $ 394 Taxes payable 61 94 Deferred tax liabilities 1 1 Other 402 331 Total $ 902 $ 820 Other Non-Current Liabilities The components of Other non-current liabilities are as follows (in millions): March 31, 2016 December 31, 2015 Taxes payable 251 223 Deferred revenue 165 159 Leases 168 166 Compensation and benefits 56 59 Other 198 162 Total $ 838 $ 769

Acquisitions and Dispositions o

Acquisitions and Dispositions of Businesses	3 Months Ended
	Mar. 31, 2016
Business Combinations [Abstract]
Acquisitions and Dispositions of Businesses	Acquisitions and Dispositions of Businesses Acquisitions The number of acquisitions completed within each reportable segment is as follows: Three months ended March 31, 2016 2015 Risk Solutions — 1 HR Solutions 2 1 Total 2 2 The following table includes the aggregate consideration transferred and the preliminary value of intangible assets recorded as a result of the Company's acquisitions (in millions): Three months ended March 31, 2016 2015 Consideration $ 21 $ 21 Intangible assets: Goodwill $ 7 $ 16 Other intangible assets 8 1 Total $ 15 $ 17 The results of operations of these acquisitions are included in the Condensed Consolidated Financial Statements as of the acquisition date. The results of operations of the Company would not have been materially different if these acquisitions had been reported from the beginning of the period in which they were acquired. Dispositions The number of dispositions completed within each reportable segment is as follows: Three months ended March 31, 2015 2014 Risk Solutions 1 1 HR Solutions 1 1 Total 2 2 Total pretax gains, net of losses, recognized were $35 million and $19 million , respectively, for the three months ended March 31, 2016 and March 31, 2015 . Gains and losses recognized as a result of a disposition are included in Other income in the Condensed Consolidated Statements of Income.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	3 Months Ended
	Mar. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets The changes in the net carrying amount of goodwill by reportable segment for the three months ended March 31, 2016 are as follows (in millions): Risk Solutions HR Solutions Total Balance as of January 1, 2016 $ 5,593 $ 2,855 $ 8,448 Goodwill related to current year acquisitions — 7 7 Goodwill related to disposals (4 ) (26 ) (30 ) Goodwill related to prior year acquisitions 2 — 2 Foreign currency translation (11 ) (5 ) (16 ) Balance as of March 31, 2016 $ 5,580 $ 2,831 $ 8,411 Other intangible assets by asset class are as follows (in millions): March 31, 2016 December 31, 2015 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Intangible assets with indefinite lives: Tradenames $ 1,019 $ — $ 1,019 $ 1,019 $ — $ 1,019 Intangible assets with finite lives: Customer related and contract based 2,871 1,851 1,020 2,886 1,809 1,077 Technology and other 535 466 69 541 457 84 Total $ 4,425 $ 2,317 $ 2,108 $ 4,446 $ 2,266 $ 2,180 Amortization expense from finite lived intangible assets was $67 million and $80 million , respectively, for the three months ended March 31, 2016 and 2015 . The estimated future amortization for finite lived intangible assets as of March 31, 2016 is as follows (in millions): Risk Solutions HR Solutions Total Remainder of 2016 $ 72 $ 128 $ 200 2017 88 137 225 2018 77 91 168 2019 67 73 140 2020 59 60 119 Thereafter 123 114 237 Total $ 486 $ 603 $ 1,089

Debt

Debt	3 Months Ended
	Mar. 31, 2016
Debt Disclosure [Abstract]
Debt	Debt Revolving Credit Facilities As of March 31, 2016 , Aon plc had two primary committed credit facilities outstanding: its $400 million U.S. credit facility expiring in March 2017 (the "2017 Facility") and its $900 million multi-currency U.S. credit facility originally expiring in February 2020. Effective February 2, 2016, the $900 million multi-currency U.S. credit facility terms were extended for one year and will now expire on February 2, 2021 (the "2021 Facility"). Each of these facilities included customary representations, warranties and covenants, including financial covenants that require Aon plc to maintain specified ratios of adjusted consolidated EBITDA to consolidated interest expense and consolidated debt to adjusted consolidated EBITDA, in each case, tested quarterly. At March 31, 2016 , Aon plc did not have borrowings under either the 2017 Facility or the 2021 Facility, and was in compliance with all covenants contained therein during the three months ended March 31, 2016 . Commercial Paper Aon Corporation, a wholly-owned subsidiary of Aon plc, has established a U.S. commercial paper program, which provides for commercial paper to be issued in an aggregate principal amount of up to $900 million , and Aon plc has established a European multi-currency commercial paper program that provides for commercial paper to be issued in an aggregate principal amount of up to €300 million . The U.S. commercial paper program is fully and unconditionally guaranteed by Aon plc and the European commercial paper program is fully and unconditionally guaranteed by Aon Corporation. In the aggregate, the Company had $184 million and $50 million of commercial paper outstanding at March 31, 2016 and December 31, 2015 , respectively, which was included in Short-term debt and current portion of long-term debt in the Company's Condensed Consolidated Statements of Financial Position. The weighted average commercial paper outstanding for the three months ended March 31, 2016 was $177 million . The weighted average interest rate of the commercial paper outstanding for the three months ended March 31, 2016 was 0.11% . Notes On March 1, 2016, Aon plc issued $750 million of 3.875% Senior Notes due December 2025. The Company used the proceeds of the issuance for general corporate purposes.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The effective tax rate on net income was 18.4% and 19.1% for the three months ended March 31, 2016 , and 2015, respectively. The effective tax rate in the first quarter of 2016 was favorably impacted by changes in the geographical distribution of income and certain discrete items.

Shareholders' Equity

Shareholders' Equity	3 Months Ended
	Mar. 31, 2016
Equity [Abstract]
Shareholders' Equity	Shareholders' Equity Ordinary Shares In April 2012, the Company's Board of Directors authorized a share repurchase program under which up to $5.0 billion of Class A Ordinary Shares may be repurchased ("2012 Share Repurchase Program"). In November 2014, the Company's Board of Directors authorized a new $5.0 billion share repurchase program in addition to the existing program ("2014 Share Repurchase Program" and, together, the "Repurchase Programs"). Under each program, shares may be repurchased through the open market or in privately negotiated transactions, from time to time, based on prevailing market conditions, and will be funded from available capital. In the three months ended March 31, 2016 , the Company repurchased 7.7 million shares at an average price per share of $97.92 for a total cost of approximately $750 million under the Repurchase Programs. Included in the 7.7 million shares repurchased during the three months ended March 31, 2016 was 0.6 million shares purchased in that period which did not settle until April 2016. These shares were settled at an average price per share of $103.58 and total cost of $65 million . In the three months ended March 31, 2015 , the Company repurchased 2.5 million shares at an average price per share of $100.15 for a total cost of $250 million under the 2012 Share Repurchase Program. In August 2015, the $5 billion of Class A Ordinary Shares authorized under the 2012 Share Repurchase Program was exhausted. At March 31, 2016 , the remaining authorized amount for share repurchase under the 2014 Share Repurchase Program is $3.3 billion . Under the Repurchase Programs, the Company has repurchased a total of 85.7 million shares for an aggregate cost of $6.7 billion . Net Income Per Share Weighted average shares outstanding are as follows (in millions): Three months ended March 31, 2016 2015 Shares for basic earnings per share 271.7 284.2 Common stock equivalents 2.0 2.9 Shares for diluted earnings per share 273.7 287.1 Certain ordinary share equivalents may be excluded from the computation of diluted net income per share if their inclusion would be antidilutive. There were 0.5 million and no shares excluded from the calculation for the three months ended March 31, 2016 and 2015 , respectively. Accumulated Other Comprehensive Loss Changes in Accumulated other comprehensive loss by component, net of related tax, are as follows (in millions): Change in Fair Value of Financial Instruments (1) Foreign Currency Translation Adjustments Post-Retirement Benefit Obligation (2) Total Balance at December 31, 2015 $ (25 ) $ (771 ) $ (2,627 ) $ (3,423 ) Other comprehensive (loss) income before reclassifications, net (7 ) (79 ) (219 ) (305 ) Amounts reclassified from accumulated other comprehensive loss: Amounts reclassified from accumulated other comprehensive loss (1 ) — 26 25 Tax benefit 1 — (8 ) (7 ) Amounts reclassified from accumulated other comprehensive loss, net — — 18 18 Net current period other comprehensive (loss) income (7 ) (79 ) (201 ) (287 ) Balance at March 31, 2016 $ (32 ) $ (850 ) $ (2,828 ) $ (3,710 ) ______________________________________________ (1) Reclassifications from this category included in Accumulated other comprehensive loss are recorded in Other income . (2) Reclassifications from this category included in Accumulated other comprehensive loss are recorded in Compensation and benefits. In March 2016, the Company entered into an insurance contract which covers a portion of the assets within select U.K. pension schemes. The transaction resulted in a decrease in Prepaid pension assets and Accumulated other comprehensive income by $267 million as the fair value in the insurance policies was deemed to be the present value of the current obligation.

Employee Benefits

Employee Benefits	3 Months Ended
	Mar. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Employee Benefits	Employee Benefits The following table provides the components of the net periodic (benefit) cost recognized in the Condensed Consolidated Statements of Income in Compensation and benefits for Aon's material U.K., U.S., and other significant international pension plans located in the Netherlands and Canada (in millions): Three months ended March 31, U.K. U.S. Other 2016 2015 2016 2015 2016 2015 Service cost $ — $ — $ — $ 1 $ — $ — Interest cost 43 49 28 33 7 8 Expected return on plan assets, net of administration expenses (64 ) (75 ) (39 ) (39 ) (12 ) (12 ) Amortization of prior-service cost 1 — — — — — Amortization of net actuarial loss 8 10 13 14 3 3 Net periodic (benefit) cost (12 ) (16 ) 2 9 (2 ) (1 ) Curtailment gain and other — — — (1 ) — — Total net periodic (benefit) cost $ (12 ) $ (16 ) $ 2 $ 8 $ (2 ) $ (1 ) Beginning in 2016, the Company has elected to utilize a full yield curve approach in the estimation of the service and interest cost components of net periodic pension and post-retirement benefit cost for Aon's major pension and other post-retirement benefit plans by applying the specific spot rates along the yield curve used in the determination of the benefit obligation to the relevant projected cash flows. In 2015 and prior years, the Company estimated these components of net periodic pension and post-retirement benefit cost by applying a single weighted-average discount rate, derived from the yield curve used to measure the benefit obligation at the beginning of the period. The Company made this change to improve the correlation between projected benefit cash flows and the corresponding yield curve spot rates and to provide a more precise measurement of service and interest costs. This change does not affect the measurement of the projected benefit obligation as the change in the service cost and interest cost is completely offset in the actuarial (gain) loss recorded in other comprehensive income. The Company accounted for this change as a change in estimate and, accordingly, will account for it prospectively. The Company expects to contribute approximately $79 million , $54 million , and $17 million , based on exchange rates as of December 31, 2015, to its significant U.K., U.S., and other significant international pension plans, respectively, during 2016. During the three months ended March 31, 2016 , contributions of $17 million , $13 million , and $7 million were made to the Company's significant U.K., U.S., and other significant international pension plans, respectively. During the three months ended March 31, 2015 , contributions of $19 million , $34 million , and $4 million were made to the Company's significant U.K., U.S., and other significant international pension plans, respectively.

Share-Based Compensation Plans

Share-Based Compensation Plans	3 Months Ended
	Mar. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation Plans	Share-Based Compensation Plans The following table summarizes share-based compensation expense recognized in the Condensed Consolidated Statements of Income in Compensation and benefits (in millions): Three months ended March 31, 2016 2015 Restricted share units ("RSUs") $ 61 $ 65 Performance share awards ("PSAs") 20 21 Share options — — Employee share purchase plans 4 4 Total share-based compensation expense $ 85 $ 90 Restricted Share Units A summary of the status of the Company's RSUs is as follows (shares in thousands): Three months ended March 31, 2016 2015 Shares Fair Value (1) Shares Fair Value (1) Non-vested at beginning of period 7,169 $ 77 8,381 $ 63 Granted 849 99 957 97 Vested (1,379 ) 73 (1,714 ) 59 Forfeited (94 ) 78 (49 ) 64 Non-vested at end of period 6,545 81 7,575 69 ______________________________________________ (1) Represents per share weighted average fair value of award at date of grant. Performance Share Awards The vesting of PSAs is contingent upon meeting a cumulative level of earnings per share performance over a three -year period. The performance conditions are not considered in the determination of the grant date fair value for these awards. The fair value of PSAs is based upon the market price of an Aon ordinary share at the date of grant. Compensation expense is recognized over the performance period based on management's estimate of the number of awards expected to vest. Compensation expense is adjusted to reflect the actual number of shares issued at the end of the programs. The actual issue of shares may range from 0 - 200% of the target number of PSAs granted, based on the terms of the plan and level of achievement of the related performance target. Dividend equivalents are not paid on PSAs. Information as of March 31, 2016 regarding the Company's target PSAs granted and shares that would be issued at current performance levels for PSAs granted during the three months ended March 31, 2016 and the years ended December 31, 2015 and 2014 , respectively, is as follows (shares in thousands, dollars in millions, except fair value): 2016 2015 2014 Target PSAs granted during period 773 993 816 Weighted average fair value per share at date of grant $ 101 $ 96 $ 81 Number of shares that would be issued based on current performance levels 773 970 1,570 Unamortized expense, based on current performance levels $ 78 $ 57 $ 33 Share Options The Company did not grant any share options during either the three months ended March 31, 2016 or the three months ended March 31, 2015 . A summary of the status of the Company's share options and related information is as follows (shares in thousands): Three months ended March 31, 2016 2015 Shares Weighted- Average Exercise Price Shares Weighted- Average Exercise Price Beginning outstanding 837 $ 40 2,300 $ 32 Granted — — — — Exercised (138 ) 38 (1,293 ) 26 Forfeited and expired (4 ) 41 (9 ) 36 Outstanding at end of period 695 40 998 39 Exercisable at end of period 695 40 998 39 The weighted average remaining contractual life, in years, of outstanding options was 2.3 years and 2.7 years at March 31, 2016 and 2015 , respectively. The aggregate intrinsic value represents the total pretax intrinsic value, based on options with an exercise price less than the Company's closing share price of $104.45 as of March 31, 2016 , which would have been received by the option holders had those option holders exercised their options as of that date. At March 31, 2016 , the aggregate intrinsic value of options outstanding, all of which were exercisable, was $44 million . Other information related to the Company's share options is as follows (in millions): Three months ended March 31, 2016 2015 Aggregate intrinsic value of stock options exercised $ 8 $ 94 Cash received from the exercise of stock options 5 34 Tax benefit realized from the exercise of stock options 2 34 Unamortized deferred compensation expense, which includes both options and RSUs, amounted to $393 million as of March 31, 2016 , with a remaining weighted-average amortization period of approximately 2.0 years.

Derivatives and Hedging

Derivatives and Hedging	3 Months Ended
	Mar. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives and Hedging	Derivatives and Hedging The Company is exposed to market risks, including changes in foreign currency exchange rates and interest rates. To manage the risk related to these exposures, the Company enters into various derivative instruments that reduce these risks by creating offsetting exposures. The Company does not enter into derivative transactions for trading or speculative purposes. Foreign Exchange Risk Management The Company is exposed to foreign exchange risk when it earns revenues, pays expenses, or enters into monetary intercompany transfers denominated in a currency that differs from its functional currency, or other transactions that are denominated in a currency other than its functional currency. The Company uses foreign exchange derivatives, typically forward contracts, options and cross currency swaps, to reduce its overall exposure to the effects of currency fluctuations on cash flows. These exposures are hedged, on average, for less than two years. These derivatives are accounted for as hedges, and changes in fair value are recorded each period in Other comprehensive income (loss) in the Condensed Consolidated Statements of Comprehensive Income. The Company also uses foreign exchange derivatives, typically forward contracts and options to economically hedge the currency exposure of the Company's global liquidity profile, including monetary assets or liabilities that are denominated in a non-functional currency of an entity, typically on a rolling 30 day basis, but may be for up to one year in the future. These derivatives are not accounted for as hedges, and changes in fair value are recorded each period in Other income in the Condensed Consolidated Statements of Income. The notional and fair values of derivative instruments are as follows (in millions): Notional Amount Derivative Assets (1) Derivative Liabilities (2) March 31, December 31, March 31, December 31, March 31, December 31, Foreign exchange contracts: Accounted for as hedges $ 804 $ 778 $ 23 $ 32 $ 17 $ 18 Not accounted for as hedges (3) 192 280 — — — — Total $ 996 $ 1,058 $ 23 $ 32 $ 17 $ 18 ______________________________________________ (1) Included within Other current assets ( $9 million at March 31, 2016 and $15 million at December 31, 2015 ) or Other non-current assets ( $14 million at March 31, 2016 and $17 million at December 31, 2015 ). (2) Included within Other current liabilities ( $12 million at March 31, 2016 and $13 million at December 31, 2015 ) or Other non-current liabilities ( $5 million at March 31, 2016 and $5 million at December 31, 2015 ). (3) These contracts typically are for 30 day durations and executed close to the last day of the most recent reporting month, thereby resulting in nominal fair values at the balance sheet date. Offsetting of financial assets and derivatives assets are as follows (in millions): Gross Amounts of Recognized Assets Gross Amounts Offset in the Statement of Financial Position Net Amounts of Assets Presented in the Statement of Financial Position (1) Derivatives accounted for as hedges: March 31, December 31, March 31, December 31, March 31, December 31, Foreign exchange contracts $ 23 $ 32 $ (8 ) $ (13 ) $ 15 $ 19 ______________________________________________ (1) Included within Other current assets ( $3 million at March 31, 2016 and $6 million at December 31, 2015 ) or Other non-current assets ( $12 million at March 31, 2016 and $13 million at December 31, 2015 ). Offsetting of financial liabilities and derivative liabilities are as follows (in millions): Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Statement of Financial Position Net Amounts of Liabilities Presented in the Statement of Financial Position (1) Derivatives accounted for as hedges: March 31, December 31, March 31, December 31, March 31, December 31, Foreign exchange contracts $ 17 $ 18 $ (7 ) $ (13 ) $ 10 $ 5 ______________________________________________ (1) Included within Other current liabilities ( $7 million at March 31, 2016 and $4 million at December 31, 2015 ) or Other non-current liabilities ( $3 million at March 31, 2016 and $1 million at December 31, 2015 ). The amounts of derivative gains (losses) recognized in the Condensed Consolidated Financial Statements for the three months ended March 31, 2016 and 2015 are as follows (in millions): Cash Flow Hedge - Foreign Exchange Contracts Location of future reclassification from Accumulated Other Comprehensive Loss Gain (Loss) Recognized in Accumulated Other Comprehensive Loss: Three months ended March 31, Compensation and Benefits Other General Expenses Interest Expense Other Income (Expense) Total 2016 $ (2 ) $ (3 ) $ — $ (5 ) $ (10 ) 2015 5 (2 ) — (4 ) (1 ) Cash Flow Hedge - Foreign Exchange Contracts Gain (Loss) Reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion): Three months ended March 31, Compensation and Benefits Other General Expenses Interest Expense Other Income Total 2016 $ 1 $ — $ — $ (1 ) $ — 2015 — — (2 ) (8 ) (10 ) The Company estimates that approximately $15 million of pretax losses currently included within Accumulated other comprehensive loss will be reclassified into earnings in the next twelve months. The amount of gain (loss) recognized in income on the ineffective portion of derivatives for the three months ended March 31, 2016 and 2015 was not material. During the three months ended March 31, 2016 , the Company recorded a gain of $1 million in Other income for foreign exchange derivatives not designated or qualifying as hedges. During the three months ended March 31, 2015 , the Company recorded a gain of $7 million in Other income for foreign exchange derivatives not designated or qualifying as hedges.

Fair Value Measurements and Fin

Fair Value Measurements and Financial Instruments	3 Months Ended
	Mar. 31, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements and Financial Instruments	Fair Value Measurements and Financial Instruments Accounting standards establish a three tier fair value hierarchy that prioritizes the inputs used in measuring fair values as follows: • Level 1 — observable inputs such as quoted prices for identical assets in active markets; • Level 2 — inputs other than quoted prices for identical assets in active markets, that are observable either directly or indirectly; and • Level 3 — unobservable inputs in which there is little or no market data which requires the use of valuation techniques and the development of assumptions. The following methods and assumptions are used to estimate the fair values of the Company's financial instruments: Money market funds are carried at cost as an approximation of fair value. Based on market convention, the Company considers cost a practical and expedient measure of fair value. Equity investments consist of domestic and international equity securities valued using the closing stock price on a national securities exchange. The Company reviews the listing of Level 1 equity securities in the portfolio and agrees the closing stock prices to a national securities exchange, and on a sample basis, independently verifies the observable inputs for Level 2 equity securities. Fixed income investments consist of corporate and government bonds. Corporate and government bonds are valued by pricing vendors who estimate fair value using recently executed transactions and proprietary models based on observable inputs, such as interest rate spreads, yield curves and credit risk. The Company obtains a detailed understanding of the models, inputs, and assumptions used in developing prices provided by its vendors. This understanding includes discussions with valuation resources at the vendor. During these discussions, the Company uses a fair value measurement questionnaire, which is part of the Company's internal controls over financial reporting, to obtain the information necessary to assert the model, inputs and assumptions used to comply with U.S. GAAP, including disclosure requirements. The Company also obtains observable inputs from the pricing vendor and independently verifies the observable inputs, as well as assesses assumptions used for reasonableness based on relevant market conditions and internal Company guidelines. If an assumption is deemed unreasonable, based on the Company's guidelines, it is then reviewed by management and the fair value estimate provided by the vendor is adjusted, if deemed appropriate. These adjustments do not occur frequently and have historically not been material to the fair value estimates used in the Condensed Consolidated Financial Statements. Derivatives are carried at fair value, based upon industry standard valuation techniques that use, where possible, current market-based or independently sourced pricing inputs, such as interest rates, currency exchange rates, or implied volatilities. Debt is carried at outstanding principal balance, less any unamortized discount or premium. Fair value is based on quoted market prices or estimates using discounted cash flow analyses based on current borrowing rates for similar types of borrowing arrangements. The following tables present the categorization of the Company's assets and liabilities that are measured at fair value on a recurring basis at March 31, 2016 and December 31, 2015 (in millions): Fair Value Measurements Using Balance at March 31, 2016 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds (1) $ 1,618 $ 1,618 $ — $ — Other investments: Corporate bonds — — — — Government bonds 1 — 1 — Equity investments 10 6 4 — Derivatives (2): Foreign exchange contracts 23 — 23 — Liabilities: Derivatives: Foreign exchange contracts 17 — 17 — ______________________________________________ (1) Included within Fiduciary assets, Short-term investments or Cash and cash equivalents in the Condensed Consolidated Statements of Financial Position, depending on their nature and initial maturity. (2) See Note 12 "Derivatives and Hedging" for additional information regarding the Company's derivative and hedging activity. Fair Value Measurements Using Balance at December 31, 2015 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds (1) $ 1,396 $ 1,396 $ — $ — Other investments: Corporate bonds — — — — Government bonds 1 — 1 — Equity investments 10 6 4 — Derivatives (2): Foreign exchange contracts 32 — 32 — Liabilities: Derivatives: Foreign exchange contracts 18 — 18 — ______________________________________________ (1) Included within Fiduciary assets, Short-term investments or Cash and cash equivalents in the Condensed Consolidated Statements of Financial Position, depending on their nature and initial maturity. (2) See Note 12 "Derivatives and Hedging" for additional information regarding the Company's derivative and hedging activity. There were no transfers of assets or liabilities between fair value hierarchy levels in either the three months ended March 31, 2016 or 2015 . The Company recognized no realized or unrealized gains or losses in the Condensed Consolidated Statements of Income during either the three months ended March 31, 2016 or 2015 , related to assets and liabilities measured at fair value using unobservable inputs. The fair value of Long-term debt is classified as Level 2 of the fair value hierarchy. The following table discloses the Company's financial instruments where the carrying amounts and fair values differ (in millions): March 31, 2016 December 31, 2015 Carrying Value Fair Value Carrying Value Fair Value Long-term debt $ 5,902 $ 6,178 $ 5,138 $ 5,386

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Aon and its subsidiaries are subject to numerous claims, tax assessments, lawsuits and proceedings that arise in the ordinary course of business, which frequently include errors and omissions ("E&O") claims. The damages claimed in these matters are or may be substantial, including, in many instances, claims for punitive, treble or extraordinary damages. While Aon maintains meaningful E&O insurance and other insurance programs to provide protection against certain losses that arise in such matters, Aon has exhausted or materially depleted its coverage under some of the policies that protect the Company and, consequently, is self-insured or materially self-insured for some claims. Accruals for these exposures, and related insurance receivables, when applicable, are included in the Condensed Consolidated Statements of Financial Position and have been recognized in Other general expenses in the Condensed Consolidated Statements of Income to the extent that losses are deemed probable and are reasonably estimable. These amounts are adjusted from time to time as developments warrant. Matters that are not probable and estimable are not accrued for in the financial statements. We have included in the matters described below certain matters in which (1) loss is probable, (2) loss is reasonably possible; that is, more than remote but not probable, or (3) there exists the reasonable possibility of loss greater than the accrued amount. In addition, we may from time to time disclose matters for which the probability of loss could be remote but the claim amounts associated with such matters are potentially significant. The reasonably possible range of loss for the matters described below, in excess of amounts that are deemed probable and estimable and therefore already accrued, is estimated to be between $0 and $0.3 billion , exclusive of any insurance coverage. These estimates are based on currently available information. As available information changes, the matters for which Aon is able to estimate may change, and the estimates themselves may change. In addition, many estimates involve significant judgment and uncertainty. For example, at the time of making an estimate, Aon may only have limited information about the facts underlying the claim, and predictions and assumptions about future court rulings and outcomes may prove to be inaccurate. Although management at present believes that the ultimate outcome of all matters described below, individually or in the aggregate, will not have a material adverse effect on the consolidated financial position of Aon, legal proceedings are subject to inherent uncertainties and unfavorable rulings or other events. Unfavorable resolutions could include substantial monetary or punitive damages imposed on Aon or its subsidiaries. If unfavorable outcomes of these matters were to occur, future results of operations or cash flows for any particular quarterly or annual period could be materially adversely affected. Current Matters A retail insurance brokerage subsidiary of Aon was sued on September 14, 2010 in the Chancery Court for Davidson County, Tennessee, Twentieth Judicial District, at Nashville by a client, Opry Mills Mall Limited Partnership ("Opry Mills") that sustained flood damage to its property in May 2010. The lawsuit seeks $200 million in coverage from numerous insurers with whom this Aon subsidiary placed the client's property insurance coverage. The insurers contend that only $50 million in coverage (which has already been paid) is available for the loss because the flood event occurred on property in a high hazard flood zone. Opry Mills is seeking full coverage from the insurers for the loss and has sued this Aon subsidiary in the alternative for the same $150 million difference on various theories of professional liability if the court determines there is not full coverage. In addition, Opry Mills seeks prejudgment interest, attorneys' fees and enhanced damages which could substantially increase Aon's exposure. In March 2015, the trial court granted partial summary judgment in favor of plaintiffs and against the insurers, holding generally that the plaintiffs are entitled to $200 million in coverage under the language of the policies. In August 2015, a jury returned a verdict in favor of Opry Mills and against the insurers in the amount of $204 million . Aon understands that the insurers intend to appeal both of these trial court decisions. Aon believes it has meritorious defenses and intends to vigorously defend itself against these claims. A pensions consulting and administration subsidiary of Hewitt before its acquisition by Aon provided advisory services to the Trustees of the Philips UK pension fund and the relevant employer of fund beneficiaries. On January 2, 2014, Philips Pension Trustees Limited and Philips Electronics UK Limited (together, "Philips") sued Aon in the High Court, Chancery Division, London alleging negligence and breach of duty. The proceedings assert Philips' right to claim damages related to Philips' use of a credit default swap hedging strategy pursuant to the supply of the advisory services, which is said to have resulted in substantial damages to Philips. Philips sought approximately £189 million ( $267 million at March 31, 2016 exchange rates), plus interest and costs. In June 2015, the High Court ordered Philips to clarify several aspects of its claim. In its clarification, Philips increased the amount of its claim to £290 million ( $410 million at March 31, 2016 exchange rates), plus interest and costs. Aon believes that it has meritorious defenses and intends to vigorously defend itself against these allegations. On June 1, 2007, the International Road Transport Union ("IRU") sued Aon in the Geneva Tribunal of First Instance in Switzerland. IRU alleges, among other things, that, between 1995 and 2004, a business acquired by Aon and, later, an Aon subsidiary (1) accepted commissions for certain insurance placements that violated a fee agreement entered between the parties and (2) negligently failed to ask certain insurance carriers to contribute to the IRU's risk management costs. IRU sought damages of approximately CHF 46 million ( $47 million at March 31, 2016 exchange rates) and $3 million , plus legal fees and interest of approximately $30 million . On December 2, 2014, the Geneva Tribunal of First Instance entered a judgment that accepted some, and rejected other, of IRU's claims. The judgment awarded IRU CHF 16.8 million ( $17 million at March 31, 2016 exchange rates) and $3.1 million , plus interest and adverse costs. The entire amount of the judgment, including interest through December 31, 2014, totaled CHF 27.9 million ( $29 million at March 31, 2016 exchange rates) and $5 million . On January 26, 2015, in return for IRU agreeing not to appeal the bulk of its dismissed claims, the Aon subsidiary agreed not to appeal a part of the judgment and to pay IRU CHF 12.8 million ( $13 million at March 31, 2016 exchange rates) and $4.7 million without Aon admitting liability. The Aon subsidiary appealed those aspects of the judgment it retained the right to appeal. IRU did not appeal. The Aon subsidiary's maximum liability on appeal is limited to CHF 8.7 million ( $9 million at March 31, 2016 exchange rates) and $115,000 (plus interest and costs) beyond what the subsidiary has already paid. The appeal is now under submission. A pensions consulting and administration subsidiary of Aon provided advisory services to the Trustees of the Gleeds pension fund in the United Kingdom and, on occasion, to the relevant employer of the fund. In April 2014, the High Court, Chancery Division, London found that certain governing documents of the fund that sought to alter the fund's benefit structure and that had been drafted by Aon were procedurally defective and therefore invalid. No lawsuit naming Aon as a party has been filed, although a tolling agreement has been entered. The High Court decision says that the additional liabilities in the pension fund resulting from the alleged defect in governing documents amount to approximately £45 million ( $64 million at March 31, 2016 exchange rates). In December 2014, the Court of Appeal granted the employer leave to appeal the High Court decision. The Court of Appeal hearing was set for October 2015, but has been postponed to permit the parties to discuss possible settlement. Aon believes that it has meritorious defenses and intends to vigorously defend itself against this potential claim. On June 29, 2015, Lyttelton Port Company Limited ("LPC") sued Aon New Zealand (Aon) in the Christchurch Registry of the High Court of New Zealand. LPC alleges, among other things, that Aon was negligent and in breach of contract in arranging LPC’s property insurance program for the period covering June 30, 2010, to June 30, 2011. LPC contends that acts and omissions by Aon caused LPC to recover less than it otherwise would have from insurers for losses suffered in the 2010/2011 Canterbury Earthquakes. LPC claims damages of approximately NZD 184 million ( $123 million at March 31, 2016 exchange rates) plus interest and costs. Aon believes that it has meritorious defenses and intends to vigorously defend itself against these claims. In addition, from time to time, Aon's clients may bring claims and take legal action pertaining to the performance of fiduciary responsibilities. Whether client claims and legal action related to the Company's performance of fiduciary responsibilities are founded or unfounded, if such claims and legal actions are resolved in a manner unfavorable to the Company, they may adversely affect Aon's financial results and materially impair the market perception of the Company and that of its products and services. Guarantees and Indemnifications In connection with the redomicile of Aon's headquarters (the "Redomestication"), the Company on April 2, 2012 entered into various agreements pursuant to which it agreed to guarantee the obligations of its subsidiaries arising under issued and outstanding debt securities. Those agreements included the (1) Amended and Restated Indenture, dated as of April 2, 2012, among Aon Corporation, Aon plc, and The Bank of New York Mellon Trust Company, N.A., as trustee (the "Trustee") (amending and restating the Indenture, dated as of September 10, 2010, between Aon Corporation and the Trustee), (2) Amended and Restated Indenture, dated as of April 2, 2012, among Aon Corporation, Aon plc and the Trustee (amending and restating the Indenture, dated as of December 16, 2002, between Aon Corporation and the Trustee), (3) Amended and Restated Indenture, dated as of April 2, 2012, among Aon Corporation, Aon plc and the Trustee (amending and restating the Indenture, dated as of January 13, 1997, as supplemented by the First Supplemental Indenture, dated as of January 13, 1997), and (4) First Supplemental Indenture, dated as of April 2, 2012, among Aon Finance N.S. 1, ULC, as issuer, Aon Corporation, as guarantor, Aon plc, as guarantor, and Computershare Trust Company of Canada, as trustee. The Company provides a variety of guarantees and indemnifications to its customers and others. The maximum potential amount of future payments represents the notional amounts that could become payable under the guarantees and indemnifications if there were a total default by the guaranteed parties, without consideration of possible recoveries under recourse provisions or other methods. These amounts may bear no relationship to the expected future payments, if any, for these guarantees and indemnifications. Any anticipated amounts payable are included in the Company's Condensed Consolidated Financial Statements, and are recorded at fair value. The Company expects that, as prudent business interests dictate, additional guarantees and indemnifications may be issued from time to time. Letters of Credit The Company had total letters of credit ("LOCs") outstanding of approximately $82 million at March 31, 2016 , compared to $58 million at December 31, 2015 . These letters of credit cover the beneficiaries related to certain of Aon's U.S. and Canadian non-qualified pension plan schemes and secure deductible retentions for the Company's own workers compensation program. The Company has also issued LOCs to cover contingent payments for taxes and other business obligations to third parties, and other guarantees for miscellaneous purposes at its international subsidiaries. Commitments The Company has provided commitments to fund certain limited partnerships in which it has an interest in the event that the general partners request funding. Some of these commitments have specific expiration dates and the maximum potential funding under these commitments was $12 million at March 31, 2016 and December 31, 2015 . During the three months ended March 31, 2016 , the Company did not fund these commitments. Premium Payments The Company has certain contractual contingent guarantees for premium payments owed by clients to certain insurance companies. The maximum exposure with respect to such contractual contingent guarantees was approximately $75 million at March 31, 2016 compared to $104 million at December 31, 2015 .

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2016
Segment Reporting [Abstract]
Segment Information	Segment Information The Company has two reportable segments: Risk Solutions and HR Solutions. Unallocated income and expenses, when combined with the operating segments and after the elimination of intersegment revenues and expenses, equal the amounts in the Condensed Consolidated Financial Statements. Reportable operating segments have been determined using a management approach, which is consistent with the basis and manner in which Aon's chief operating decision-maker ("CODM") uses financial information for the purposes of allocating resources and evaluating performance. The CODM assesses performance based on operating income and generally accounts for inter-segment revenue as if the revenue were from third parties and at what management believes are current market prices. The Company does not present net assets by segment as this information is not reviewed by the CODM. Risk Solutions acts as an advisor and insurance and reinsurance broker, helping clients manage their risks, via consultation, as well as negotiation and placement of insurance risk with insurance carriers through Aon's global distribution network. HR Solutions partners with organizations to solve their most complex benefits, talent and related financial challenges, and improve business performance by designing, implementing, communicating and administering a wide range of human capital, retirement, investment management, health care, compensation and talent management strategies. Aon's total revenue is as follows (in millions): Three months ended March 31, 2016 2015 Risk Solutions $ 1,872 $ 1,895 HR Solutions 930 970 Intersegment eliminations (10 ) (18 ) Total revenue $ 2,792 $ 2,847 Commissions, fees and other revenues by product are as follows (in millions): Three months ended March 31, 2016 2015 Retail brokerage $ 1,495 $ 1,513 Reinsurance brokerage 372 377 Total Risk Solutions Segment 1,867 1,890 Consulting services 374 371 Outsourcing 560 604 Intrasegment (4 ) (5 ) Total HR Solutions Segment 930 970 Intersegment (10 ) (18 ) Total commissions, fees and other revenue $ 2,787 $ 2,842 Fiduciary investment income by segment is as follows (in millions): Three months ended March 31, 2016 2015 Risk Solutions $ 5 $ 5 HR Solutions — — Total fiduciary investment income $ 5 $ 5 A reconciliation of segment operating income before tax to income before income taxes is as follows (in millions): Three months ended March 31, 2016 2015 Risk Solutions $ 429 $ 412 HR Solutions 67 76 Segment income before income taxes 496 488 Unallocated expenses (46 ) (47 ) Interest income 2 3 Interest expense (69 ) (65 ) Other income 18 42 Income before income taxes $ 401 $ 421 Unallocated expenses include administrative or other costs not attributable to the operating segments, such as corporate governance costs. Interest income represents income earned primarily on operating cash balances and certain income producing securities. Interest expense represents the cost of debt obligations. Other income consists of equity earnings, realized gains or losses on the sale of investments, gains or losses on the disposal of businesses, gains or losses on derivatives, and gains or losses on foreign currency transactions.

Guarantee of Registered Securit

Guarantee of Registered Securities	3 Months Ended
	Mar. 31, 2016
Guarantee of Registered Securities [Abstract]
Guarantee of Registered Securities	Guarantee of Registered Securities As described in Note 14, in connection with the Redomestication, Aon plc entered into various agreements pursuant to which it agreed to guarantee the obligations of Aon Corporation arising under issued and outstanding debt securities, including the 3.125% Notes due May 2016, the 5.00% Notes due September 2020, the 8.205% Notes due January 2027 and the 6.25% Notes due September 2040. Aon Corporation is a 100% indirectly owned subsidiary of Aon plc. All guarantees of Aon plc are full and unconditional. There are no other subsidiaries of Aon plc that are guarantors of the debt. In addition, Aon Corporation entered into an agreement pursuant to which it agreed to guarantee the obligations of Aon plc arising under the 4.250% Notes due 2042 exchanged for Aon Corporation's outstanding 8.205% Notes due January 2027 and also agreed to guarantee the obligations of Aon plc arising under the 2.8% Notes due 2021, the 4.45% Notes due 2043, the 4.00% Notes due November 2023, the 2.875% Notes due May 2026, the 3.50% Notes due June 2024, the 4.60% Notes due June 2044, the 4.75% Notes due May 2045, and the 3.875% Notes due December 2025. In each case, the guarantee of Aon Corporation is full and unconditional. There are no subsidiaries of Aon plc, other than Aon Corporation, that are guarantors of the 4.250% Notes due 2042, the 4.45% Notes due 2043, the 4.00% Notes due 2023, the 2.875% Notes due 2026, the 3.50% Notes due 2024, the 4.60% Notes due 2044, or the 4.75% Notes due 2045. As a result of the existence of these guarantees, the Company is required by Rule 3-10 of Regulation S-X to present the financial information set forth in this footnote. The following tables set forth condensed consolidating statements of income for the three months ended March 31, 2016 and 2015 , condensed consolidating statements of comprehensive income for the three months ended March 31, 2016 and 2015 , condensed consolidating statements of financial position as of March 31, 2016 and December 31, 2015 , and condensed consolidating statements of cash flows for the three months ended March 31, 2016 and 2015 in accordance with Rule 3-10 of Regulation S-X. The condensed consolidating financial information includes the accounts of Aon plc, the accounts of Aon Corporation, and the combined accounts of the non-guarantor subsidiaries. The condensed consolidating financial statements are presented in all periods as a merger under common control, with Aon plc presented as the parent company in all periods prior and subsequent to the Redomestication. The principal consolidating adjustments are to eliminate the investment in subsidiaries and intercompany balances and transactions. In January 2015, Aon plc transferred its ownership of all of its directly held subsidiaries to Aon Global Holdings Limited, an intermediate holding company. The financial results of Aon Global Holdings Limited are included in the Other Non-Guarantor Subsidiaries column of the Condensed Consolidating Financial Statements. The Company has reflected the transfer of Aon Corporation from Aon plc to Aon Global Holdings Limited below for all periods presented. Condensed Consolidating Statement of Income Three months ended March 31, 2016 Other Aon Aon Non-Guarantor Consolidating (millions) plc Corporation Subsidiaries Adjustments Consolidated Revenue Commissions, fees and other $ — $ — $ 2,787 $ — $ 2,787 Fiduciary investment income — — 5 — 5 Total revenue — — 2,792 — 2,792 Expenses Compensation and benefits 43 3 1,603 — 1,649 Other general expenses 7 2 684 — 693 Total operating expenses 50 5 2,287 — 2,342 Operating (loss) income (50 ) (5 ) 505 — 450 Interest income (7 ) 5 4 — 2 Interest expense (38 ) (28 ) (3 ) — (69 ) Intercompany interest income (expense) 4 (133 ) 129 — — Intercompany other (expense) income (54 ) 1 53 — — Other income — (5 ) 23 — 18 (Loss) income before taxes (145 ) (165 ) 711 — 401 Income tax (benefit) expense (26 ) (62 ) 162 — 74 (Loss) income before equity in earnings of subsidiaries (119 ) (103 ) 549 — 327 Equity in earnings of subsidiaries, net of tax 434 367 264 (1,065 ) — Net income 315 264 813 (1,065 ) 327 Less: Net income attributable to noncontrolling interests — — 12 — 12 Net income attributable to Aon shareholders $ 315 $ 264 $ 801 $ (1,065 ) $ 315 Condensed Consolidating Statement of Income Three months ended March 31, 2015 Other Aon Aon Non-Guarantor Consolidating (millions) plc Corporation Subsidiaries Adjustments Consolidated Revenue Commissions, fees and other $ — $ — $ 2,842 $ — $ 2,842 Fiduciary investment income — — 5 — 5 Total revenue — — 2,847 — 2,847 Expenses Compensation and benefits 52 11 1,620 — 1,683 Other general expenses 13 2 708 — 723 Total operating expenses 65 13 2,328 — 2,406 Operating (loss) income (65 ) (13 ) 519 — 441 Interest income (5 ) 3 5 — 3 Interest expense (25 ) (34 ) (6 ) — (65 ) Intercompany interest income (expense) 119 (105 ) (14 ) — — Intercompany other (expense) income (50 ) (8 ) 58 — — Other income 2 8 32 — 42 Income (loss) before taxes (24 ) (149 ) 594 — 421 Income tax expense (benefit) (5 ) (50 ) 135 — 80 Income (loss) before equity in earnings of subsidiaries (19 ) (99 ) 459 — 341 Equity in earnings of subsidiaries, net of tax 347 403 304 (1,054 ) — Net income 328 304 763 (1,054 ) 341 Less: Net income attributable to noncontrolling interests — — 13 — 13 Net income attributable to Aon shareholders $ 328 $ 304 $ 750 $ (1,054 ) $ 328 Condensed Consolidating Statement of Comprehensive Income Three months ended March 31, 2016 Other Aon Aon Non-Guarantor Consolidating (millions) plc Corporation Subsidiaries Adjustments Consolidated Net income $ 315 $ 264 $ 813 $ (1,065 ) $ 327 Less: Net income attributable to noncontrolling interests — — 12 — 12 Net income attributable to Aon shareholders $ 315 $ 264 $ 801 $ (1,065 ) $ 315 Other comprehensive (loss) income, net of tax: Change in fair value of financial instruments — (2 ) (5 ) — (7 ) Foreign currency translation adjustments — 11 (90 ) — (79 ) Post-retirement benefit obligation — 13 (214 ) — (201 ) Total other comprehensive loss — 22 (309 ) — (287 ) Equity in other comprehensive loss of subsidiaries, net of tax (287 ) (314 ) (292 ) 893 — Less: Other comprehensive income attributable to noncontrolling interests — — — — — Total other comprehensive loss attributable to Aon shareholders (287 ) (292 ) (601 ) 893 (287 ) Comprehensive income attributable to Aon shareholders $ 28 $ (28 ) $ 200 $ (172 ) $ 28 Condensed Consolidating Statement of Comprehensive Income Three months ended March 31, 2015 Other Aon Aon Non-Guarantor Consolidating (millions) plc Corporation Subsidiaries Adjustments Consolidated Net income $ 328 $ 304 $ 763 $ (1,054 ) $ 341 Less: Net income attributable to noncontrolling interests — — 13 — 13 Net income attributable to Aon shareholders $ 328 $ 304 $ 750 $ (1,054 ) $ 328 Other comprehensive income (loss), net of tax: Change in fair value of financial instruments — (1 ) 6 — 5 Foreign currency translation adjustments — (23 ) (299 ) — (322 ) Post-retirement benefit obligation — 8 15 — 23 Total other comprehensive (loss) income — (16 ) (278 ) — (294 ) Equity in other comprehensive income of subsidiaries, net of tax (293 ) (267 ) (283 ) 843 — Less: Other comprehensive income attributable to noncontrolling interests — — (1 ) — (1 ) Total other comprehensive income attributable to Aon shareholders (293 ) (283 ) (560 ) 843 (293 ) Comprehensive income attributable to Aon Shareholders $ 35 $ 21 $ 190 $ (211 ) $ 35 Condensed Consolidating Statement of Financial Position As of March 31, 2016 Other Aon Aon Non-Guarantor Consolidating (millions) plc Corporation Subsidiaries Adjustments Consolidated ASSETS Cash and cash equivalents $ — $ 1,537 $ 1,457 $ (2,529 ) $ 465 Short-term investments — 453 134 — 587 Receivables, net 2 — 2,589 — 2,591 Fiduciary assets — — 9,776 — 9,776 Intercompany receivables 43 3,786 8,759 (12,588 ) — Other current assets — 206 418 (2 ) 622 Total Current Assets 45 5,982 23,133 (15,119 ) 14,041 Goodwill — — 8,411 — 8,411 Intangible assets, net — — 2,108 — 2,108 Fixed assets, net — — 766 — 766 Non-current deferred tax assets 154 556 137 (676 ) 171 Intercompany receivables 379 537 8,716 (9,632 ) — Prepaid pension — 6 731 — 737 Other non-current assets — 114 465 — 579 Investment in subsidiary 11,949 16,643 239 (28,831 ) — TOTAL ASSETS $ 12,527 $ 23,838 $ 44,706 $ (54,258 ) $ 26,813 LIABILITIES AND EQUITY Accounts payable and accrued liabilities $ 2,624 $ 22 $ 1,303 $ (2,529 ) $ 1,420 Short-term debt and current portion of long-term debt 184 500 11 — 695 Fiduciary liabilities — — 9,776 — 9,776 Intercompany payables 141 11,365 1,082 (12,588 ) — Other current liabilities 85 60 759 (2 ) 902 Total Current Liabilities 3,034 11,947 12,931 (15,119 ) 12,793 Long-term debt 4,206 1,413 283 — 5,902 Non-current deferred tax liabilities — — 853 (676 ) 177 Pension, other post-retirement and other post-employment liabilities — 1,295 461 — 1,756 Intercompany payables — 8,881 751 (9,632 ) — Other non-current liabilities 6 63 769 — 838 TOTAL LIABILITIES 7,246 23,599 16,048 (25,427 ) 21,466 TOTAL AON SHAREHOLDERS' EQUITY 5,281 239 28,592 (28,831 ) 5,281 Noncontrolling interests — — 66 — 66 TOTAL EQUITY 5,281 239 28,658 (28,831 ) 5,347 TOTAL LIABILITIES AND EQUITY $ 12,527 $ 23,838 $ 44,706 $ (54,258 ) $ 26,813 Condensed Consolidating Statement of Financial Position As of December 31, 2015 Other Aon Aon Non-Guarantor Consolidating (millions) plc Corporation Subsidiaries Adjustments Consolidated ASSETS Cash and cash equivalents $ — $ 2,083 $ 1,242 $ (2,941 ) $ 384 Short-term investments — 209 147 — 356 Receivables, net 1 — 2,733 — 2,734 Fiduciary assets — — 9,932 — 9,932 Intercompany receivables 432 1,950 7,957 (10,339 ) — Other current assets — 217 347 (2 ) 562 Total Current Assets 433 4,459 22,358 (13,282 ) 13,968 Goodwill — — 8,448 — 8,448 Intangible assets, net — — 2,180 — 2,180 Fixed assets, net — — 765 — 765 Intercompany receivables 375 526 8,633 (9,534 ) — Non-current deferred tax assets 154 558 107 (678 ) 141 Prepaid pension — 6 1,027 — 1,033 Other non-current assets — 119 557 (84 ) 592 Investment in subsidiary 11,804 16,534 369 (28,707 ) — TOTAL ASSETS $ 12,766 $ 22,202 $ 44,444 $ (52,285 ) $ 27,127 LIABILITIES AND EQUITY Accounts payable and accrued liabilities $ 2,988 $ 45 $ 1,680 $ (2,941 ) $ 1,772 Short-term debt and current portion of long-term debt — 550 12 — 562 Fiduciary liabilities — — 9,932 — 9,932 Intercompany payables 167 9,518 654 (10,339 ) — Other current liabilities 47 56 720 (3 ) 820 Total Current Liabilities 3,202 10,169 12,998 (13,283 ) 13,086 Long-term debt 3,451 1,412 275 — 5,138 Non-current deferred tax liabilities — — 854 (678 ) 176 Pension, other post-retirement and other post-employment liabilities — 1,313 482 — 1,795 Intercompany payables — 8,799 735 (9,534 ) — Other non-current liabilities 7 140 705 (83 ) 769 TOTAL LIABILITIES 6,660 21,833 16,049 (23,578 ) 20,964 TOTAL AON SHAREHOLDERS' EQUITY 6,106 369 28,338 (28,707 ) 6,106 Noncontrolling interests — — 57 — 57 TOTAL EQUITY 6,106 369 28,395 (28,707 ) 6,163 TOTAL LIABILITIES AND EQUITY $ 12,766 $ 22,202 $ 44,444 $ (52,285 ) $ 27,127 Condensed Consolidating Statement of Cash Flows Three months ended March 31, 2016 Aon Aon Other Non-Guarantor Consolidating (millions) plc Corporation Subsidiaries Adjustments Consolidated CASH FLOWS FROM OPERATING ACTIVITIES CASH PROVIDED BY (USED FOR) OPERATING ACTIVITIES $ (47 ) $ (37 ) $ 357 $ — $ 273 CASH FLOWS FROM INVESTING ACTIVITIES Proceeds from investments — 9 4 — 13 Purchases of investments — (5 ) (9 ) — (14 ) Net (purchases) sales of short-term investments - non-fiduciary — (244 ) 17 — (227 ) Acquisition of businesses, net of cash acquired — — (16 ) — (16 ) Proceeds from sale of businesses — — 97 — 97 Capital expenditures — — (52 ) — (52 ) CASH PROVIDED BY (USED FOR) INVESTING ACTIVITIES — (240 ) 41 — (199 ) CASH FLOWS FROM FINANCING ACTIVITIES Share repurchase (685 ) — — — (685 ) Advances from (to) affiliates (46 ) (219 ) (147 ) 412 — Issuance of shares for employee benefit plans (64 ) — (1 ) — (65 ) Issuance of debt 996 50 (1 ) — 1,045 Repayment of debt (72 ) (100 ) (3 ) — (175 ) Cash dividends to shareholders (82 ) — — — (82 ) Noncontrolling interests and other financing activities — — (42 ) — (42 ) CASH (USED FOR) PROVIDED BY FINANCING ACTIVITIES 47 (269 ) (194 ) 412 (4 ) EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS — — 11 — 11 NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS — (546 ) 215 412 81 CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR — 2,083 1,242 (2,941 ) 384 CASH AND CASH EQUIVALENTS AT END OF PERIOD $ — $ 1,537 $ 1,457 $ (2,529 ) $ 465 Condensed Consolidating Statement of Cash Flows Three months ended March 31, 2015 Other Aon Aon Non-Guarantor Consolidating (millions) plc Corporation Subsidiaries Adjustments Consolidated CASH FLOWS FROM OPERATING ACTIVITIES CASH PROVIDED BY (USED FOR) OPERATING ACTIVITIES $ 164 $ (188 ) $ 322 $ — $ 298 CASH FLOWS FROM INVESTING ACTIVITIES Proceeds from investments — — 3 — 3 Purchases of investments — (1 ) — — (1 ) Net (purchases) sales of short-term investments - non-fiduciary — (1 ) 43 — 42 Acquisition of businesses, net of cash acquired — — (21 ) — (21 ) Proceeds from sale of businesses — — 41 — 41 Capital expenditures — — (62 ) — (62 ) CASH PROVIDED BY INVESTING ACTIVITIES — (2 ) 4 — 2 CASH FLOWS FROM FINANCING ACTIVITIES Share repurchase (250 ) — — — (250 ) Advances from (to) affiliates 157 (385 ) (984 ) 1,212 — Issuance of shares for employee benefit plans (114 ) — — — (114 ) Issuance of debt 114 756 — — 870 Repayment of debt — (678 ) (8 ) — (686 ) Cash dividends to shareholders (71 ) — — — (71 ) Noncontrolling interests and other financing activities — — (6 ) — (6 ) CASH (USED FOR) PROVIDED BY FINANCING ACTIVITIES (164 ) (307 ) (998 ) 1,212 (257 ) EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS — — (39 ) — (39 ) NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS — (497 ) (711 ) 1,212 4 CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR — 2,727 1,361 (3,714 ) 374 CASH AND CASH EQUIVALENTS AT END OF PERIOD $ — $ 2,230 $ 650 $ (2,502 ) $ 378

Other Financial Data (Tables)

Other Financial Data (Tables)	3 Months Ended
	Mar. 31, 2016
Other Financial Data [Abstract]
Schedule of Other Income (Expense)	Other income consists of the following (in millions): Three months ended March 31, 2016 2015 Foreign currency remeasurement (loss) gain (17 ) 24 Gain on disposal of business 35 19 Equity earnings 2 2 Income (loss) on financial instruments (2 ) (3 ) Total $ 18 $ 42
Schedule of Allowance for Doubtful Accounts	An analysis of the allowance for doubtful accounts is as follows (in millions): Three months ended March 31, 2016 2015 Balance at beginning of period $ 58 $ 74 Provision charged to Other general expenses 6 8 Accounts written off, net of recoveries (2 ) (9 ) Foreign currency translation — (3 ) Balance at end of period $ 62 $ 70
Schedule of Other Current Assets	The components of Other current assets are as follows (in millions): March 31, 2016 December 31, 2015 Taxes receivable $ 122 $ 94 Deferred tax assets 232 232 Prepaid expenses 168 130 Deferred project costs 92 92 Other 8 14 Total $ 622 $ 562
Schedule of Other Non-current Assets	The components of Other non-current assets are as follows (in millions): March 31, 2016 December 31, 2015 Deferred project costs $ 205 $ 210 Investments 131 135 Taxes receivable 81 82 Other 162 165 Total $ 579 $ 592
Schedule of Other Current Liabilities	The components of Other current liabilities are as follows (in millions): March 31, 2016 December 31, 2015 Deferred revenue $ 438 $ 394 Taxes payable 61 94 Deferred tax liabilities 1 1 Other 402 331 Total $ 902 $ 820
Schedule of Other Non-current Liabilities	The components of Other non-current liabilities are as follows (in millions): March 31, 2016 December 31, 2015 Taxes payable 251 223 Deferred revenue 165 159 Leases 168 166 Compensation and benefits 56 59 Other 198 162 Total $ 838 $ 769

Acquisitions and Dispositions25

Acquisitions and Dispositions of Businesses (Tables)	3 Months Ended
	Mar. 31, 2016
Business Combinations [Abstract]
Consideration transferred and preliminary value of intangible assets	The number of acquisitions completed within each reportable segment is as follows: Three months ended March 31, 2016 2015 Risk Solutions — 1 HR Solutions 2 1 Total 2 2
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The following table includes the aggregate consideration transferred and the preliminary value of intangible assets recorded as a result of the Company's acquisitions (in millions): Three months ended March 31, 2016 2015 Consideration $ 21 $ 21 Intangible assets: Goodwill $ 7 $ 16 Other intangible assets 8 1 Total $ 15 $ 17
Disposal Groups, Including Discontinued Operations	The number of dispositions completed within each reportable segment is as follows: Three months ended March 31, 2015 2014 Risk Solutions 1 1 HR Solutions 1 1 Total 2 2

Goodwill and Other Intangible26

Goodwill and Other Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of changes in the net carrying amount of goodwill by operating segment	The changes in the net carrying amount of goodwill by reportable segment for the three months ended March 31, 2016 are as follows (in millions): Risk Solutions HR Solutions Total Balance as of January 1, 2016 $ 5,593 $ 2,855 $ 8,448 Goodwill related to current year acquisitions — 7 7 Goodwill related to disposals (4 ) (26 ) (30 ) Goodwill related to prior year acquisitions 2 — 2 Foreign currency translation (11 ) (5 ) (16 ) Balance as of March 31, 2016 $ 5,580 $ 2,831 $ 8,411
Schedule of other intangible assets by asset class	Other intangible assets by asset class are as follows (in millions): March 31, 2016 December 31, 2015 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Intangible assets with indefinite lives: Tradenames $ 1,019 $ — $ 1,019 $ 1,019 $ — $ 1,019 Intangible assets with finite lives: Customer related and contract based 2,871 1,851 1,020 2,886 1,809 1,077 Technology and other 535 466 69 541 457 84 Total $ 4,425 $ 2,317 $ 2,108 $ 4,446 $ 2,266 $ 2,180
Schedule of estimated future amortization expense on intangible assets	The estimated future amortization for finite lived intangible assets as of March 31, 2016 is as follows (in millions): Risk Solutions HR Solutions Total Remainder of 2016 $ 72 $ 128 $ 200 2017 88 137 225 2018 77 91 168 2019 67 73 140 2020 59 60 119 Thereafter 123 114 237 Total $ 486 $ 603 $ 1,089

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2016
Equity [Abstract]
Schedule of components of weighted average number of shares	Weighted average shares outstanding are as follows (in millions): Three months ended March 31, 2016 2015 Shares for basic earnings per share 271.7 284.2 Common stock equivalents 2.0 2.9 Shares for diluted earnings per share 273.7 287.1
Components of Accumulated other comprehensive loss, net of related tax	Changes in Accumulated other comprehensive loss by component, net of related tax, are as follows (in millions): Change in Fair Value of Financial Instruments (1) Foreign Currency Translation Adjustments Post-Retirement Benefit Obligation (2) Total Balance at December 31, 2015 $ (25 ) $ (771 ) $ (2,627 ) $ (3,423 ) Other comprehensive (loss) income before reclassifications, net (7 ) (79 ) (219 ) (305 ) Amounts reclassified from accumulated other comprehensive loss: Amounts reclassified from accumulated other comprehensive loss (1 ) — 26 25 Tax benefit 1 — (8 ) (7 ) Amounts reclassified from accumulated other comprehensive loss, net — — 18 18 Net current period other comprehensive (loss) income (7 ) (79 ) (201 ) (287 ) Balance at March 31, 2016 $ (32 ) $ (850 ) $ (2,828 ) $ (3,710 ) ______________________________________________ (1) Reclassifications from this category included in Accumulated other comprehensive loss are recorded in Other income . (2) Reclassifications from this category included in Accumulated other comprehensive loss are recorded in Compensation and benefits

Employee Benefits (Tables)

Employee Benefits (Tables)	3 Months Ended
	Mar. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Components of net periodic benefit cost for the pension plans	The following table provides the components of the net periodic (benefit) cost recognized in the Condensed Consolidated Statements of Income in Compensation and benefits for Aon's material U.K., U.S., and other significant international pension plans located in the Netherlands and Canada (in millions): Three months ended March 31, U.K. U.S. Other 2016 2015 2016 2015 2016 2015 Service cost $ — $ — $ — $ 1 $ — $ — Interest cost 43 49 28 33 7 8 Expected return on plan assets, net of administration expenses (64 ) (75 ) (39 ) (39 ) (12 ) (12 ) Amortization of prior-service cost 1 — — — — — Amortization of net actuarial loss 8 10 13 14 3 3 Net periodic (benefit) cost (12 ) (16 ) 2 9 (2 ) (1 ) Curtailment gain and other — — — (1 ) — — Total net periodic (benefit) cost $ (12 ) $ (16 ) $ 2 $ 8 $ (2 ) $ (1 )

Share-Based Compensation Plans

Share-Based Compensation Plans (Tables)	3 Months Ended
	Mar. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-based compensation expense recognized in continuing operations	The following table summarizes share-based compensation expense recognized in the Condensed Consolidated Statements of Income in Compensation and benefits (in millions): Three months ended March 31, 2016 2015 Restricted share units ("RSUs") $ 61 $ 65 Performance share awards ("PSAs") 20 21 Share options — — Employee share purchase plans 4 4 Total share-based compensation expense $ 85 $ 90
Restricted share unit activity	A summary of the status of the Company's RSUs is as follows (shares in thousands): Three months ended March 31, 2016 2015 Shares Fair Value (1) Shares Fair Value (1) Non-vested at beginning of period 7,169 $ 77 8,381 $ 63 Granted 849 99 957 97 Vested (1,379 ) 73 (1,714 ) 59 Forfeited (94 ) 78 (49 ) 64 Non-vested at end of period 6,545 81 7,575 69 ______________________________________________ (1) Represents per share weighted average fair value of award at date of grant.
Performance-based plans	Information as of March 31, 2016 regarding the Company's target PSAs granted and shares that would be issued at current performance levels for PSAs granted during the three months ended March 31, 2016 and the years ended December 31, 2015 and 2014 , respectively, is as follows (shares in thousands, dollars in millions, except fair value): 2016 2015 2014 Target PSAs granted during period 773 993 816 Weighted average fair value per share at date of grant $ 101 $ 96 $ 81 Number of shares that would be issued based on current performance levels 773 970 1,570 Unamortized expense, based on current performance levels $ 78 $ 57 $ 33
Share options and related information	A summary of the status of the Company's share options and related information is as follows (shares in thousands): Three months ended March 31, 2016 2015 Shares Weighted- Average Exercise Price Shares Weighted- Average Exercise Price Beginning outstanding 837 $ 40 2,300 $ 32 Granted — — — — Exercised (138 ) 38 (1,293 ) 26 Forfeited and expired (4 ) 41 (9 ) 36 Outstanding at end of period 695 40 998 39 Exercisable at end of period 695 40 998 39
Other information related to the company's share options	Other information related to the Company's share options is as follows (in millions): Three months ended March 31, 2016 2015 Aggregate intrinsic value of stock options exercised $ 8 $ 94 Cash received from the exercise of stock options 5 34 Tax benefit realized from the exercise of stock options 2 34

Derivatives and Hedging (Tables

Derivatives and Hedging (Tables)	3 Months Ended
	Mar. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Notional and fair values of derivative instruments	The notional and fair values of derivative instruments are as follows (in millions): Notional Amount Derivative Assets (1) Derivative Liabilities (2) March 31, December 31, March 31, December 31, March 31, December 31, Foreign exchange contracts: Accounted for as hedges $ 804 $ 778 $ 23 $ 32 $ 17 $ 18 Not accounted for as hedges (3) 192 280 — — — — Total $ 996 $ 1,058 $ 23 $ 32 $ 17 $ 18 ______________________________________________ (1) Included within Other current assets ( $9 million at March 31, 2016 and $15 million at December 31, 2015 ) or Other non-current assets ( $14 million at March 31, 2016 and $17 million at December 31, 2015 ). (2) Included within Other current liabilities ( $12 million at March 31, 2016 and $13 million at December 31, 2015 ) or Other non-current liabilities ( $5 million at March 31, 2016 and $5 million at December 31, 2015 ). (3) These contracts typically are for 30 day durations and executed close to the last day of the most recent reporting month, thereby resulting in nominal fair values at the balance sheet date. Offsetting of financial assets and derivatives assets are as follows (in millions): Gross Amounts of Recognized Assets Gross Amounts Offset in the Statement of Financial Position Net Amounts of Assets Presented in the Statement of Financial Position (1) Derivatives accounted for as hedges: March 31, December 31, March 31, December 31, March 31, December 31, Foreign exchange contracts $ 23 $ 32 $ (8 ) $ (13 ) $ 15 $ 19 ______________________________________________ (1) Included within Other current assets ( $3 million at March 31, 2016 and $6 million at December 31, 2015 ) or Other non-current assets ( $12 million at March 31, 2016 and $13 million at December 31, 2015 ). Offsetting of financial liabilities and derivative liabilities are as follows (in millions): Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Statement of Financial Position Net Amounts of Liabilities Presented in the Statement of Financial Position (1) Derivatives accounted for as hedges: March 31, December 31, March 31, December 31, March 31, December 31, Foreign exchange contracts $ 17 $ 18 $ (7 ) $ (13 ) $ 10 $ 5 ______________________________________________ (1) Included within Other current liabilities ( $7 million at March 31, 2016 and $4 million at December 31, 2015 ) or Other non-current liabilities ( $3 million at March 31, 2016 and $1 million at December 31, 2015 )
Derivative gains (losses)	The amounts of derivative gains (losses) recognized in the Condensed Consolidated Financial Statements for the three months ended March 31, 2016 and 2015 are as follows (in millions): Cash Flow Hedge - Foreign Exchange Contracts Location of future reclassification from Accumulated Other Comprehensive Loss Gain (Loss) Recognized in Accumulated Other Comprehensive Loss: Three months ended March 31, Compensation and Benefits Other General Expenses Interest Expense Other Income (Expense) Total 2016 $ (2 ) $ (3 ) $ — $ (5 ) $ (10 ) 2015 5 (2 ) — (4 ) (1 ) Cash Flow Hedge - Foreign Exchange Contracts Gain (Loss) Reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion): Three months ended March 31, Compensation and Benefits Other General Expenses Interest Expense Other Income Total 2016 $ 1 $ — $ — $ (1 ) $ — 2015 — — (2 ) (8 ) (10 )

Fair Value Measurements and F31

Fair Value Measurements and Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2016
Fair Value Disclosures [Abstract]
Schedule of assets and liabilities that are measured at fair value on a recurring basis	The following tables present the categorization of the Company's assets and liabilities that are measured at fair value on a recurring basis at March 31, 2016 and December 31, 2015 (in millions): Fair Value Measurements Using Balance at March 31, 2016 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds (1) $ 1,618 $ 1,618 $ — $ — Other investments: Corporate bonds — — — — Government bonds 1 — 1 — Equity investments 10 6 4 — Derivatives (2): Foreign exchange contracts 23 — 23 — Liabilities: Derivatives: Foreign exchange contracts 17 — 17 — ______________________________________________ (1) Included within Fiduciary assets, Short-term investments or Cash and cash equivalents in the Condensed Consolidated Statements of Financial Position, depending on their nature and initial maturity. (2) See Note 12 "Derivatives and Hedging" for additional information regarding the Company's derivative and hedging activity. Fair Value Measurements Using Balance at December 31, 2015 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds (1) $ 1,396 $ 1,396 $ — $ — Other investments: Corporate bonds — — — — Government bonds 1 — 1 — Equity investments 10 6 4 — Derivatives (2): Foreign exchange contracts 32 — 32 — Liabilities: Derivatives: Foreign exchange contracts 18 — 18 — ______________________________________________ (1) Included within Fiduciary assets, Short-term investments or Cash and cash equivalents in the Condensed Consolidated Statements of Financial Position, depending on their nature and initial maturity. (2) See Note 12 "Derivatives and Hedging" for additional information regarding the Company's derivative and hedging activity.
Schedule of financial instruments where the carrying amounts and fair values differ	The fair value of Long-term debt is classified as Level 2 of the fair value hierarchy. The following table discloses the Company's financial instruments where the carrying amounts and fair values differ (in millions): March 31, 2016 December 31, 2015 Carrying Value Fair Value Carrying Value Fair Value Long-term debt $ 5,902 $ 6,178 $ 5,138 $ 5,386

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2016
Segment Reporting [Abstract]
Schedule of total revenue by business segments	Aon's total revenue is as follows (in millions): Three months ended March 31, 2016 2015 Risk Solutions $ 1,872 $ 1,895 HR Solutions 930 970 Intersegment eliminations (10 ) (18 ) Total revenue $ 2,792 $ 2,847
Schedule of commissions, fees and other revenues by products	Commissions, fees and other revenues by product are as follows (in millions): Three months ended March 31, 2016 2015 Retail brokerage $ 1,495 $ 1,513 Reinsurance brokerage 372 377 Total Risk Solutions Segment 1,867 1,890 Consulting services 374 371 Outsourcing 560 604 Intrasegment (4 ) (5 ) Total HR Solutions Segment 930 970 Intersegment (10 ) (18 ) Total commissions, fees and other revenue $ 2,787 $ 2,842
Schedule of fiduciary investment income by business segments	Fiduciary investment income by segment is as follows (in millions): Three months ended March 31, 2016 2015 Risk Solutions $ 5 $ 5 HR Solutions — — Total fiduciary investment income $ 5 $ 5
Schedule of reconciliation of segment income before tax to income from continuing operations before income taxes	A reconciliation of segment operating income before tax to income before income taxes is as follows (in millions): Three months ended March 31, 2016 2015 Risk Solutions $ 429 $ 412 HR Solutions 67 76 Segment income before income taxes 496 488 Unallocated expenses (46 ) (47 ) Interest income 2 3 Interest expense (69 ) (65 ) Other income 18 42 Income before income taxes $ 401 $ 421

Guarantee of Registered Secur33

Guarantee of Registered Securities (Tables)	3 Months Ended
	Mar. 31, 2016
Guarantee of Registered Securities [Abstract]
Condensed Consolidating Statements of Income	Condensed Consolidating Statement of Income Three months ended March 31, 2016 Other Aon Aon Non-Guarantor Consolidating (millions) plc Corporation Subsidiaries Adjustments Consolidated Revenue Commissions, fees and other $ — $ — $ 2,787 $ — $ 2,787 Fiduciary investment income — — 5 — 5 Total revenue — — 2,792 — 2,792 Expenses Compensation and benefits 43 3 1,603 — 1,649 Other general expenses 7 2 684 — 693 Total operating expenses 50 5 2,287 — 2,342 Operating (loss) income (50 ) (5 ) 505 — 450 Interest income (7 ) 5 4 — 2 Interest expense (38 ) (28 ) (3 ) — (69 ) Intercompany interest income (expense) 4 (133 ) 129 — — Intercompany other (expense) income (54 ) 1 53 — — Other income — (5 ) 23 — 18 (Loss) income before taxes (145 ) (165 ) 711 — 401 Income tax (benefit) expense (26 ) (62 ) 162 — 74 (Loss) income before equity in earnings of subsidiaries (119 ) (103 ) 549 — 327 Equity in earnings of subsidiaries, net of tax 434 367 264 (1,065 ) — Net income 315 264 813 (1,065 ) 327 Less: Net income attributable to noncontrolling interests — — 12 — 12 Net income attributable to Aon shareholders $ 315 $ 264 $ 801 $ (1,065 ) $ 315 Condensed Consolidating Statement of Income Three months ended March 31, 2015 Other Aon Aon Non-Guarantor Consolidating (millions) plc Corporation Subsidiaries Adjustments Consolidated Revenue Commissions, fees and other $ — $ — $ 2,842 $ — $ 2,842 Fiduciary investment income — — 5 — 5 Total revenue — — 2,847 — 2,847 Expenses Compensation and benefits 52 11 1,620 — 1,683 Other general expenses 13 2 708 — 723 Total operating expenses 65 13 2,328 — 2,406 Operating (loss) income (65 ) (13 ) 519 — 441 Interest income (5 ) 3 5 — 3 Interest expense (25 ) (34 ) (6 ) — (65 ) Intercompany interest income (expense) 119 (105 ) (14 ) — — Intercompany other (expense) income (50 ) (8 ) 58 — — Other income 2 8 32 — 42 Income (loss) before taxes (24 ) (149 ) 594 — 421 Income tax expense (benefit) (5 ) (50 ) 135 — 80 Income (loss) before equity in earnings of subsidiaries (19 ) (99 ) 459 — 341 Equity in earnings of subsidiaries, net of tax 347 403 304 (1,054 ) — Net income 328 304 763 (1,054 ) 341 Less: Net income attributable to noncontrolling interests — — 13 — 13 Net income attributable to Aon shareholders $ 328 $ 304 $ 750 $ (1,054 ) $ 328
Condensed Consolidating Statements of Comprehensive Income	Condensed Consolidating Statement of Comprehensive Income Three months ended March 31, 2016 Other Aon Aon Non-Guarantor Consolidating (millions) plc Corporation Subsidiaries Adjustments Consolidated Net income $ 315 $ 264 $ 813 $ (1,065 ) $ 327 Less: Net income attributable to noncontrolling interests — — 12 — 12 Net income attributable to Aon shareholders $ 315 $ 264 $ 801 $ (1,065 ) $ 315 Other comprehensive (loss) income, net of tax: Change in fair value of financial instruments — (2 ) (5 ) — (7 ) Foreign currency translation adjustments — 11 (90 ) — (79 ) Post-retirement benefit obligation — 13 (214 ) — (201 ) Total other comprehensive loss — 22 (309 ) — (287 ) Equity in other comprehensive loss of subsidiaries, net of tax (287 ) (314 ) (292 ) 893 — Less: Other comprehensive income attributable to noncontrolling interests — — — — — Total other comprehensive loss attributable to Aon shareholders (287 ) (292 ) (601 ) 893 (287 ) Comprehensive income attributable to Aon shareholders $ 28 $ (28 ) $ 200 $ (172 ) $ 28 Condensed Consolidating Statement of Comprehensive Income Three months ended March 31, 2015 Other Aon Aon Non-Guarantor Consolidating (millions) plc Corporation Subsidiaries Adjustments Consolidated Net income $ 328 $ 304 $ 763 $ (1,054 ) $ 341 Less: Net income attributable to noncontrolling interests — — 13 — 13 Net income attributable to Aon shareholders $ 328 $ 304 $ 750 $ (1,054 ) $ 328 Other comprehensive income (loss), net of tax: Change in fair value of financial instruments — (1 ) 6 — 5 Foreign currency translation adjustments — (23 ) (299 ) — (322 ) Post-retirement benefit obligation — 8 15 — 23 Total other comprehensive (loss) income — (16 ) (278 ) — (294 ) Equity in other comprehensive income of subsidiaries, net of tax (293 ) (267 ) (283 ) 843 — Less: Other comprehensive income attributable to noncontrolling interests — — (1 ) — (1 ) Total other comprehensive income attributable to Aon shareholders (293 ) (283 ) (560 ) 843 (293 ) Comprehensive income attributable to Aon Shareholders $ 35 $ 21 $ 190 $ (211 ) $ 35
Condensed Consolidating Statements of Financial Position	Condensed Consolidating Statement of Financial Position As of March 31, 2016 Other Aon Aon Non-Guarantor Consolidating (millions) plc Corporation Subsidiaries Adjustments Consolidated ASSETS Cash and cash equivalents $ — $ 1,537 $ 1,457 $ (2,529 ) $ 465 Short-term investments — 453 134 — 587 Receivables, net 2 — 2,589 — 2,591 Fiduciary assets — — 9,776 — 9,776 Intercompany receivables 43 3,786 8,759 (12,588 ) — Other current assets — 206 418 (2 ) 622 Total Current Assets 45 5,982 23,133 (15,119 ) 14,041 Goodwill — — 8,411 — 8,411 Intangible assets, net — — 2,108 — 2,108 Fixed assets, net — — 766 — 766 Non-current deferred tax assets 154 556 137 (676 ) 171 Intercompany receivables 379 537 8,716 (9,632 ) — Prepaid pension — 6 731 — 737 Other non-current assets — 114 465 — 579 Investment in subsidiary 11,949 16,643 239 (28,831 ) — TOTAL ASSETS $ 12,527 $ 23,838 $ 44,706 $ (54,258 ) $ 26,813 LIABILITIES AND EQUITY Accounts payable and accrued liabilities $ 2,624 $ 22 $ 1,303 $ (2,529 ) $ 1,420 Short-term debt and current portion of long-term debt 184 500 11 — 695 Fiduciary liabilities — — 9,776 — 9,776 Intercompany payables 141 11,365 1,082 (12,588 ) — Other current liabilities 85 60 759 (2 ) 902 Total Current Liabilities 3,034 11,947 12,931 (15,119 ) 12,793 Long-term debt 4,206 1,413 283 — 5,902 Non-current deferred tax liabilities — — 853 (676 ) 177 Pension, other post-retirement and other post-employment liabilities — 1,295 461 — 1,756 Intercompany payables — 8,881 751 (9,632 ) — Other non-current liabilities 6 63 769 — 838 TOTAL LIABILITIES 7,246 23,599 16,048 (25,427 ) 21,466 TOTAL AON SHAREHOLDERS' EQUITY 5,281 239 28,592 (28,831 ) 5,281 Noncontrolling interests — — 66 — 66 TOTAL EQUITY 5,281 239 28,658 (28,831 ) 5,347 TOTAL LIABILITIES AND EQUITY $ 12,527 $ 23,838 $ 44,706 $ (54,258 ) $ 26,813 Condensed Consolidating Statement of Financial Position As of December 31, 2015 Other Aon Aon Non-Guarantor Consolidating (millions) plc Corporation Subsidiaries Adjustments Consolidated ASSETS Cash and cash equivalents $ — $ 2,083 $ 1,242 $ (2,941 ) $ 384 Short-term investments — 209 147 — 356 Receivables, net 1 — 2,733 — 2,734 Fiduciary assets — — 9,932 — 9,932 Intercompany receivables 432 1,950 7,957 (10,339 ) — Other current assets — 217 347 (2 ) 562 Total Current Assets 433 4,459 22,358 (13,282 ) 13,968 Goodwill — — 8,448 — 8,448 Intangible assets, net — — 2,180 — 2,180 Fixed assets, net — — 765 — 765 Intercompany receivables 375 526 8,633 (9,534 ) — Non-current deferred tax assets 154 558 107 (678 ) 141 Prepaid pension — 6 1,027 — 1,033 Other non-current assets — 119 557 (84 ) 592 Investment in subsidiary 11,804 16,534 369 (28,707 ) — TOTAL ASSETS $ 12,766 $ 22,202 $ 44,444 $ (52,285 ) $ 27,127 LIABILITIES AND EQUITY Accounts payable and accrued liabilities $ 2,988 $ 45 $ 1,680 $ (2,941 ) $ 1,772 Short-term debt and current portion of long-term debt — 550 12 — 562 Fiduciary liabilities — — 9,932 — 9,932 Intercompany payables 167 9,518 654 (10,339 ) — Other current liabilities 47 56 720 (3 ) 820 Total Current Liabilities 3,202 10,169 12,998 (13,283 ) 13,086 Long-term debt 3,451 1,412 275 — 5,138 Non-current deferred tax liabilities — — 854 (678 ) 176 Pension, other post-retirement and other post-employment liabilities — 1,313 482 — 1,795 Intercompany payables — 8,799 735 (9,534 ) — Other non-current liabilities 7 140 705 (83 ) 769 TOTAL LIABILITIES 6,660 21,833 16,049 (23,578 ) 20,964 TOTAL AON SHAREHOLDERS' EQUITY 6,106 369 28,338 (28,707 ) 6,106 Noncontrolling interests — — 57 — 57 TOTAL EQUITY 6,106 369 28,395 (28,707 ) 6,163 TOTAL LIABILITIES AND EQUITY $ 12,766 $ 22,202 $ 44,444 $ (52,285 ) $ 27,127
Condensed Consolidating Statements of Cash Flows	Condensed Consolidating Statement of Cash Flows Three months ended March 31, 2016 Aon Aon Other Non-Guarantor Consolidating (millions) plc Corporation Subsidiaries Adjustments Consolidated CASH FLOWS FROM OPERATING ACTIVITIES CASH PROVIDED BY (USED FOR) OPERATING ACTIVITIES $ (47 ) $ (37 ) $ 357 $ — $ 273 CASH FLOWS FROM INVESTING ACTIVITIES Proceeds from investments — 9 4 — 13 Purchases of investments — (5 ) (9 ) — (14 ) Net (purchases) sales of short-term investments - non-fiduciary — (244 ) 17 — (227 ) Acquisition of businesses, net of cash acquired — — (16 ) — (16 ) Proceeds from sale of businesses — — 97 — 97 Capital expenditures — — (52 ) — (52 ) CASH PROVIDED BY (USED FOR) INVESTING ACTIVITIES — (240 ) 41 — (199 ) CASH FLOWS FROM FINANCING ACTIVITIES Share repurchase (685 ) — — — (685 ) Advances from (to) affiliates (46 ) (219 ) (147 ) 412 — Issuance of shares for employee benefit plans (64 ) — (1 ) — (65 ) Issuance of debt 996 50 (1 ) — 1,045 Repayment of debt (72 ) (100 ) (3 ) — (175 ) Cash dividends to shareholders (82 ) — — — (82 ) Noncontrolling interests and other financing activities — — (42 ) — (42 ) CASH (USED FOR) PROVIDED BY FINANCING ACTIVITIES 47 (269 ) (194 ) 412 (4 ) EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS — — 11 — 11 NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS — (546 ) 215 412 81 CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR — 2,083 1,242 (2,941 ) 384 CASH AND CASH EQUIVALENTS AT END OF PERIOD $ — $ 1,537 $ 1,457 $ (2,529 ) $ 465 Condensed Consolidating Statement of Cash Flows Three months ended March 31, 2015 Other Aon Aon Non-Guarantor Consolidating (millions) plc Corporation Subsidiaries Adjustments Consolidated CASH FLOWS FROM OPERATING ACTIVITIES CASH PROVIDED BY (USED FOR) OPERATING ACTIVITIES $ 164 $ (188 ) $ 322 $ — $ 298 CASH FLOWS FROM INVESTING ACTIVITIES Proceeds from investments — — 3 — 3 Purchases of investments — (1 ) — — (1 ) Net (purchases) sales of short-term investments - non-fiduciary — (1 ) 43 — 42 Acquisition of businesses, net of cash acquired — — (21 ) — (21 ) Proceeds from sale of businesses — — 41 — 41 Capital expenditures — — (62 ) — (62 ) CASH PROVIDED BY INVESTING ACTIVITIES — (2 ) 4 — 2 CASH FLOWS FROM FINANCING ACTIVITIES Share repurchase (250 ) — — — (250 ) Advances from (to) affiliates 157 (385 ) (984 ) 1,212 — Issuance of shares for employee benefit plans (114 ) — — — (114 ) Issuance of debt 114 756 — — 870 Repayment of debt — (678 ) (8 ) — (686 ) Cash dividends to shareholders (71 ) — — — (71 ) Noncontrolling interests and other financing activities — — (6 ) — (6 ) CASH (USED FOR) PROVIDED BY FINANCING ACTIVITIES (164 ) (307 ) (998 ) 1,212 (257 ) EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS — — (39 ) — (39 ) NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS — (497 ) (711 ) 1,212 4 CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR — 2,727 1,361 (3,714 ) 374 CASH AND CASH EQUIVALENTS AT END OF PERIOD $ — $ 2,230 $ 650 $ (2,502 ) $ 378

Basis of Presentation (Details)

Basis of Presentation (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Summary of Reclassification From Prior Period [Line Items]
Prepaid pension	$ 737		$ 1,033
Reclassification adjustment, amount transferred from operating activities to issuance of shares for employee benefit plans in financing activities	128	$ 162
Reclassification adjustment, amount transferred from account payable and accrued liabilities in operating activities to financing activities		118
Reclassification Adjustment, amount transferred from other assets and liabilities in operating activities to financing activities		44
Noncontrolling interests and other financing activities	$ (42)	(6)
Scenario, Previously Reported [Member]
Summary of Reclassification From Prior Period [Line Items]
Noncontrolling interests and other financing activities		(5)
Dividends paid to noncontrolling interests		$ (1)
Accounting Standard Update 2015-03 [Member] | Other Current Assets [Member]
Summary of Reclassification From Prior Period [Line Items]
Deferred Finance Costs, Net			4
Accounting Standard Update 2015-03 [Member] | Other Noncurrent Assets [Member]
Summary of Reclassification From Prior Period [Line Items]
Deferred Finance Costs, Net			$ 33

Cash and Cash Equivalents and35

Cash and Cash Equivalents and Short-term Investments (Details) £ in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2016GBP (£)	Mar. 31, 2016USD ($)	Dec. 31, 2015GBP (£)	Dec. 31, 2015USD ($)
Cash, Cash Equivalents, and Short-term Investments [Abstract]
Short-term investment, minimum maturity period (in excess of)	3 months
Short-term investment, maximum maturity period (less than)	1 year
Cash and cash equivalents and Short-term investments		$ 1,052		$ 740
Restricted cash		95		105
Operating funds in U.K.	£ 43.3	$ 61.2	£ 43.3	$ 64.6

Other Financial Data - Schedule

Other Financial Data - Schedule of Other Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Other (Expense) Income
Foreign currency remeasurement (loss) gain	$ (17)	$ 24
Gain on disposal of business	35	19
Equity earnings	2	2
Income (loss) on financial instruments	(2)	(3)
Total	$ 18	$ 42

Other Financial Data - Schedu37

Other Financial Data - Schedule of Allowance for Doubtful Accounts (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of period	$ 58	$ 74
Provision charged to Other general expenses	6	8
Accounts written off, net of recoveries	(2)	(9)
Foreign currency translation	0	(3)
Balance at end of period	$ 62	$ 70

Other Financial Data - Schedu38

Other Financial Data - Schedule of Other Current Assets (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Other Financial Data [Abstract]
Taxes receivable	$ 122	$ 94
Deferred tax assets	232	232
Prepaid expenses	168	130
Deferred project costs	92	92
Other	8	14
Total	$ 622	$ 562

Other Financial Data - Schedu39

Other Financial Data - Schedule of Other Non-current Assets (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Other Financial Data [Abstract]
Deferred project costs	$ 205	$ 210
Investments	131	135
Taxes receivable	81	82
Other	162	165
Total	$ 579	$ 592

Other Financial Data - Schedu40

Other Financial Data - Schedule of Other Current Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Other Financial Data [Abstract]
Deferred revenue	$ 438	$ 394
Taxes payable	61	94
Deferred tax liabilities	1	1
Other	402	331
Total	$ 902	$ 820

Other Financial Data - Schedu41

Other Financial Data - Schedule of Other Non-current Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Other Financial Data [Abstract]
Taxes payable	$ 251	$ 223
Deferred revenue	165	159
Leases	168	166
Compensation and benefits	56	59
Other	198	162
Total	$ 838	$ 769

Acquisitions and Dispositions42

Acquisitions and Dispositions of Businesses - Acquisitions (Details) $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)acquisition	Mar. 31, 2015USD ($)acquisition	Dec. 31, 2015USD ($)
Business Acquisition
Number of business acquired under business combination | acquisition	2	2
Intangible assets:
Goodwill	$ 8,411		$ 8,448
Business Acquisition 1 [Member]
Business Acquisition
Consideration	21	$ 21
Intangible assets:
Goodwill	7	16
Other intangible assets	8	1
Total	$ 15	$ 17
Risk Solutions [Member]
Business Acquisition
Number of business acquired under business combination | acquisition	0	1
Intangible assets:
Goodwill	$ 5,580		5,593
HR Solutions [Member]
Business Acquisition
Number of business acquired under business combination | acquisition	2	1
Intangible assets:
Goodwill	$ 2,831		$ 2,855

Acquisitions and Dispositions43

Acquisitions and Dispositions of Businesses - Dispositions (Details) $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)disposal	Mar. 31, 2015USD ($)disposal
Dispositions
Gain on disposal of business | $	$ 35	$ 19
Disposal Group, Not Discontinued Operations [Member]
Dispositions
Number of dispositions	2	2
Gain on disposal of business | $	$ 35	$ (19)
Disposal Group, Not Discontinued Operations [Member] | Risk Solutions [Member]
Dispositions
Number of dispositions	1	1
Disposal Group, Not Discontinued Operations [Member] | HR Solutions [Member]
Dispositions
Number of dispositions	1	1

Goodwill and Other Intangible44

Goodwill and Other Intangible Assets (Details) $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)
Changes in the net carrying amount of goodwill by operating segment (in millions)
Beginning balance	$ 8,448
Goodwill related to current year acquisitions	7
Goodwill related to disposals	(30)
Goodwill related to prior year acquisitions	2
Foreign currency translation	(16)
Ending balance	8,411
Risk Solutions [Member]
Changes in the net carrying amount of goodwill by operating segment (in millions)
Beginning balance	5,593
Goodwill related to current year acquisitions	0
Goodwill related to disposals	(4)
Goodwill related to prior year acquisitions	2
Foreign currency translation	(11)
Ending balance	5,580
HR Solutions [Member]
Changes in the net carrying amount of goodwill by operating segment (in millions)
Beginning balance	2,855
Goodwill related to current year acquisitions	7
Goodwill related to disposals	(26)
Goodwill related to prior year acquisitions	0
Foreign currency translation	(5)
Ending balance	$ 2,831

Goodwill and Other Intangible45

Goodwill and Other Intangible Assets (Details 2) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Intangible assets with indefinite lives
Tradenames	$ 1,019		$ 1,019
Intangible assets with finite lives
Intangible assets with finite lives, Gross Carrying Amount	4,425		4,446
Intangible assets with finite lives, Accumulated Amortization	2,317		2,266
Intangible assets, Net Carrying Amount	2,108		2,180
Amortization expense on intangible assets	67	$ 80
Estimated amortization for intangible assets
Remainder of 2016	200
2,017	225
2,018	168
2,019	140
2,020	119
Thereafter	237
Total	1,089
Risk Solutions [Member]
Estimated amortization for intangible assets
Remainder of 2016	72
2,017	88
2,018	77
2,019	67
2,020	59
Thereafter	123
Total	486
HR Solutions [Member]
Estimated amortization for intangible assets
Remainder of 2016	128
2,017	137
2,018	91
2,019	73
2,020	60
Thereafter	114
Total	603
Customer related and contract based [Member]
Intangible assets with finite lives
Intangible assets with finite lives, Gross Carrying Amount	2,871		2,886
Intangible assets with finite lives, Accumulated Amortization	1,851		1,809
Intangible assets, Net Carrying Amount	1,020		1,077
Technology and other [Member]
Intangible assets with finite lives
Intangible assets with finite lives, Gross Carrying Amount	535		541
Intangible assets with finite lives, Accumulated Amortization	466		457
Intangible assets, Net Carrying Amount	$ 69		$ 84

Debt (Details)

Debt (Details)	Feb. 02, 2016USD ($)	Mar. 31, 2016USD ($)	Mar. 31, 2016EUR (€)	Mar. 31, 2016USD ($)	Mar. 01, 2016USD ($)	Dec. 31, 2015USD ($)credit_facility	Feb. 02, 2015USD ($)
Debt Instrument [Line Items]
Number of credit facilities | credit_facility						2
Commercial paper [Member]
Debt Instrument [Line Items]
Total debt				$ 184,000,000		$ 50,000,000
Weighted average commercial paper outstanding		$ 177,000,000
Weighted-average interest rates (as a percent)		0.11%
3.875% due in December 2025 [Member] | Notes Payable, Other Payables [Member]
Debt Instrument [Line Items]
Face amount of debt					$ 750,000,000
Debt interest rate percentage (as a percent)			3.875%	3.875%	3.875%
Credit Facility Expiring March 2017 [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity						$ 400,000,000
Foreign Line of Credit [Member] | 2020 Facility [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity							$ 900,000,000
Foreign Line of Credit [Member] | 2021 Facility [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 900,000,000
Extended term (in years)	1 year
Commercial paper [Member] | US Commercial Paper Program [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				$ 900,000,000
Commercial paper [Member] | European Multi Currency Paper Program [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity | €			€ 300,000,000

Income Taxes (Details)

Income Taxes (Details)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Effective income tax rate	18.40%	19.10%

Shareholders' Equity (Details)

Shareholders' Equity (Details) - USD ($)	1 Months Ended	3 Months Ended		40 Months Ended	41 Months Ended
	Apr. 29, 2016	Mar. 31, 2016	Mar. 31, 2015	Aug. 31, 2015	Sep. 30, 2015	Nov. 30, 2014	Apr. 30, 2012
Common Stock Programs
Shares purchased (in shares)					85,700,000
Total cost of shares purchased		$ 750,000,000			$ 6,700,000,000
Weighted average shares outstanding
Shares for basic earnings per share (in shares)		271,700,000	284,200,000
Common stock equivalents (in shares)		2,000,000	2,900,000
Shares for diluted earnings per share (in shares)		273,700,000	287,100,000
Number of shares excluded from the calculation of diluted earnings per share		500,000	0
Decrease on prepaid pension		$ 267,000,000
Share Repurchase Program of 2014 [Member]
Common Stock Programs
Share repurchase authorization limit (up to)						$ 5,000,000,000
Share repurchase, remaining authorization limit		$ 3,300,000,000
2012 - Share Repurchase Program [Member]
Common Stock Programs
Share repurchase authorization limit (up to)							$ 5,000,000,000
Shares purchased (in shares)		7,700,000	2,500,000
Average price per share of stock repurchased		$ 97.92	$ 100.15
Total cost of shares purchased		$ 750,000,000	$ 250,000,000	$ 5,000,000,000
Subsequent Event [Member] | 2012 - Share Repurchase Program [Member]
Common Stock Programs
Shares purchased (in shares)	600,000
Average price per share of stock repurchased	$ 103.58
Total cost of shares purchased	$ 65,000,000

Shareholders' Equity (Details 2

Shareholders' Equity (Details 2) $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)
Changes in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ (3,423)
Other comprehensive (loss) income before reclassifications, net	(305)
Amounts reclassified from accumulated other comprehensive loss:
Amounts reclassified from accumulated other comprehensive loss	25
Tax benefit	(7)
Amounts reclassified from accumulated other comprehensive loss, net	18
Net current period other comprehensive (loss) income	(287)
Ending balance	(3,710)
Change in Fair Value of Financial Instruments [Member]
Changes in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(25)
Other comprehensive (loss) income before reclassifications, net	(7)
Amounts reclassified from accumulated other comprehensive loss:
Amounts reclassified from accumulated other comprehensive loss	(1)
Tax benefit	1
Amounts reclassified from accumulated other comprehensive loss, net	0
Net current period other comprehensive (loss) income	(7)
Ending balance	(32)
Foreign Currency Translation Adjustments [Member]
Changes in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(771)
Other comprehensive (loss) income before reclassifications, net	(79)
Amounts reclassified from accumulated other comprehensive loss:
Amounts reclassified from accumulated other comprehensive loss	0
Tax benefit	0
Amounts reclassified from accumulated other comprehensive loss, net	0
Net current period other comprehensive (loss) income	(79)
Ending balance	(850)
Post-Retirement Benefit Obligation [Member]
Changes in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(2,627)
Other comprehensive (loss) income before reclassifications, net	(219)
Amounts reclassified from accumulated other comprehensive loss:
Amounts reclassified from accumulated other comprehensive loss	26
Tax benefit	(8)
Amounts reclassified from accumulated other comprehensive loss, net	18
Net current period other comprehensive (loss) income	(201)
Ending balance	$ (2,828)

Employee Benefits (Details)

Employee Benefits (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
U.K. [Member]
Defined Benefit Plan Disclosure
Service cost	$ 0	$ 0
Interest cost	43	49
Expected return on plan assets, net of administration expenses	(64)	(75)
Amortization of prior-service cost	1	0
Amortization of net actuarial loss	8	10
Net periodic (benefit) cost	(12)	(16)
Curtailment gain and other	0	0
Total net periodic (benefit) cost	(12)	(16)
Estimate of contributions to defined benefit pension plans for the current fiscal year	79
Contributions made to defined benefit pension plans	17	19
U.S. [Member]
Defined Benefit Plan Disclosure
Service cost	0	1
Interest cost	28	33
Expected return on plan assets, net of administration expenses	(39)	(39)
Amortization of prior-service cost	0	0
Amortization of net actuarial loss	13	14
Net periodic (benefit) cost	2	9
Curtailment gain and other	0	(1)
Total net periodic (benefit) cost	2	8
Estimate of contributions to defined benefit pension plans for the current fiscal year	54
Contributions made to defined benefit pension plans	13	34
Other [Member]
Defined Benefit Plan Disclosure
Service cost	0	0
Interest cost	7	8
Expected return on plan assets, net of administration expenses	(12)	(12)
Amortization of prior-service cost	0	0
Amortization of net actuarial loss	3	3
Net periodic (benefit) cost	(2)	(1)
Curtailment gain and other	0	0
Total net periodic (benefit) cost	(2)	(1)
Estimate of contributions to defined benefit pension plans for the current fiscal year	17
Contributions made to defined benefit pension plans	$ 7	$ 4

Share-Based Compensation Plan51

Share-Based Compensation Plans - Share-based compensation expenses recognized (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 85	$ 90
Restricted share units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	61	65
Performance share awards (“PSAs”) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	20	21
Share options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	0	0
Employee share purchase plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 4	$ 4

Share-Based Compensation Plan52

Share-Based Compensation Plans - Restricted share unit activity (Details) - Restricted share units (RSUs) [Member] - $ / shares shares in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Non-vested share awards (in shares)
Non-vested at beginning of period (in shares)	7,169	8,381
Granted (in shares)	849	957
Vested (in shares)	(1,379)	(1,714)
Forfeited (in shares)	(94)	(49)
Non-vested at end of period (in shares)	6,545	7,575
Weighted Average Fair value
Non-vested at beginning of period (in dollars per share)	$ 77	$ 63
Granted (in dollars per share)	99	97
Vested (in dollars per share)	73	59
Forfeited (in dollars per share)	78	64
Non-vested at end of period (in dollars per share)	$ 81	$ 69

Share-Based Compensation Plan53

Share-Based Compensation Plans - Performance Share Awards Narrative (Details) - Performance Shares [Member]	3 Months Ended
	Mar. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting conditions period (in years)	3 years
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued, percent	0.00%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued, percent	200.00%

Share-Based Compensation Plan54

Share-Based Compensation Plans - Schedule of Performance-based plans (Details) - Performance Shares [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target PSAs granted during period (in shares)	773	993	816
Weighted average fair value per share at date of grant (in dollars per share)	$ 101	$ 96	$ 81
Number of shares that would be issued based on current performance levels (in shares)	773	970	1,570
Unamortized expense, based on current performance levels	$ 78			$ 57	$ 33

Share-Based Compensation Plan55

Share-Based Compensation Plans - Share options activity (Details) - Share options [Member] - $ / shares shares in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Share Options
Beginning outstanding (in shares)	837	2,300
Granted (in shares)	0	0
Exercised (in shares)	(138)	(1,293)
Forfeited and expired (in shares)	(4)	(9)
Outstanding at end of period (in shares)	695	998
Exercisable at end of period (in shares)	695	998
Weighted-Average Exercise Price
Beginning outstanding (in dollars per share)	$ 40	$ 32
Granted (in dollars per share)	0	0
Exercised (in dollars per share)	38	26
Forfeited and expired (in dollars per share)	41	36
Outstanding at end of period (in dollars per share)	40	39
Exercisable at end of period (in dollars per share)	$ 40	$ 39

Share-Based Compensation Plan56

Share-Based Compensation Plans - Stock Option Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Closing share price (in dollars per share)	$ 104.45
Aggregate intrinsic value of options outstanding	$ 44
Unamortized deferred compensation expense	$ 393
Remaining weighted-average amortization period (in years)	2 years
Share options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average remaining contractual life (in years)	2 years 3 months 18 days	2 years 8 months 12 days

Share-Based Compensation Plan57

Share-Based Compensation Plans - Other information related to the company's share options (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Aggregate intrinsic value of stock options exercised	$ 8	$ 94
Cash received from the exercise of stock options	5	34
Tax benefit realized from the exercise of stock options	$ 2	$ 34

Derivatives and Hedging - Forei

Derivatives and Hedging - Foreign Exchange Risk Management Narrative (Details)	3 Months Ended
	Mar. 31, 2016
Cash Flow Hedging [Member]
Derivative [Line Items]
Foreign currency exposures, maximum average hedging period (less than)	2 years
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Foreign currency exposures, maximum hedging period (up to)	1 year

Derivatives and Hedging - Inter

Derivatives and Hedging - Interest Rate Management Risk Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Derivative [Line Items]
Estimated pretax losses currently included within Accumulated Other Comprehensive Loss that will be reclassified to earnings in next twelve months	$ 15
Not Designated as Hedging Instrument [Member] | Foreign exchange contracts [Member]
Derivative [Line Items]
Derivative gain	$ 1	$ 7

Derivatives and Hedging - Notio

Derivatives and Hedging - Notional and fair values of derivative instruments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Derivatives, Fair Value
Notional Amount	$ 996	$ 1,058
Derivative Assets	23	32
Derivative Liabilities	$ 17	18
Term of derivative contract	30 days
Other Current Assets [Member]
Derivatives, Fair Value
Derivative Assets	$ 9	15
Net Amounts of Assets Presented in the Statement of Financial Position	3	6
Other Noncurrent Assets [Member]
Derivatives, Fair Value
Derivative Assets	14	17
Net Amounts of Assets Presented in the Statement of Financial Position	12	13
Other Current Liabilities [Member]
Derivatives, Fair Value
Derivative Liabilities	12	13
Net Amounts of Liabilities Presented in the Statement of Financial Position	7	4
Other Noncurrent Liabilities [Member]
Derivatives, Fair Value
Derivative Liabilities	5	5
Net Amounts of Liabilities Presented in the Statement of Financial Position	3	1
Derivatives accounted for as hedges [Member] | Foreign exchange contracts [Member]
Derivatives, Fair Value
Notional Amount	804	778
Derivative Assets	23	32
Derivative Liabilities	17	18
Gross Amounts Offset in the Statement of Financial Position	(8)	(13)
Net Amounts of Assets Presented in the Statement of Financial Position	15	19
Gross Amounts Offset in the Statement of Financial Position	(7)	(13)
Net Amounts of Liabilities Presented in the Statement of Financial Position	10	5
Not Designated as Hedging Instrument [Member] | Foreign exchange contracts [Member]
Derivatives, Fair Value
Notional Amount	192	280
Derivative Assets	0	0
Derivative Liabilities	$ 0	$ 0

Derivatives and Hedging - Sched

Derivatives and Hedging - Schedule of amounts of derivative gains (losses) recognized in the Consolidated Financial Statements (Details) - Cash Flow Hedging [Member] - Foreign exchange contracts [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Derivative [Line Items]
Gain (Loss) recognized in accumulated other comprehensive income	$ (10)	$ (1)
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	0	(10)
Compensation and Benefits [Member]
Derivative [Line Items]
Gain (Loss) recognized in accumulated other comprehensive income	(2)	5
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	1	0
Other General Expenses [Member]
Derivative [Line Items]
Gain (Loss) recognized in accumulated other comprehensive income	(3)	(2)
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	0	0
Interest Expense [Member]
Derivative [Line Items]
Gain (Loss) recognized in accumulated other comprehensive income	0	0
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	0	(2)
Other Income (Expense) [Member]
Derivative [Line Items]
Gain (Loss) recognized in accumulated other comprehensive income	(5)	(4)
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	$ (1)	$ (8)

Fair Value Measurements and F62

Fair Value Measurements and Financial Instruments - Schedule of assets and liabilities that are measured at fair value on a recurring basis (Details) - Recurring [Member] - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Money market funds and highly liquid debt securities
Assets:
Money market funds and highly liquid debt securities	$ 1,618	$ 1,396
Corporate bonds [Member]
Assets:
Other investments	0	0
Government bonds [Member]
Assets:
Other investments	1	1
Equity investments [Member]
Assets:
Other investments	10	10
Foreign exchange contracts [Member]
Assets:
Derivatives	23	32
Liabilities:
Derivatives	17	18
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Money market funds and highly liquid debt securities
Assets:
Money market funds and highly liquid debt securities	1,618	1,396
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate bonds [Member]
Assets:
Other investments	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Government bonds [Member]
Assets:
Other investments	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Equity investments [Member]
Assets:
Other investments	6	6
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Foreign exchange contracts [Member]
Assets:
Derivatives	0	0
Liabilities:
Derivatives	0	0
Significant Other Observable Inputs (Level 2) [Member] | Money market funds and highly liquid debt securities
Assets:
Money market funds and highly liquid debt securities	0	0
Significant Other Observable Inputs (Level 2) [Member] | Corporate bonds [Member]
Assets:
Other investments	0	0
Significant Other Observable Inputs (Level 2) [Member] | Government bonds [Member]
Assets:
Other investments	1	1
Significant Other Observable Inputs (Level 2) [Member] | Equity investments [Member]
Assets:
Other investments	4	4
Significant Other Observable Inputs (Level 2) [Member] | Foreign exchange contracts [Member]
Assets:
Derivatives	23	32
Liabilities:
Derivatives	17	18
Significant Unobservable Inputs (Level 3) [Member] | Money market funds and highly liquid debt securities
Assets:
Money market funds and highly liquid debt securities	0	0
Significant Unobservable Inputs (Level 3) [Member] | Corporate bonds [Member]
Assets:
Other investments	0	0
Significant Unobservable Inputs (Level 3) [Member] | Government bonds [Member]
Assets:
Other investments	0	0
Significant Unobservable Inputs (Level 3) [Member] | Equity investments [Member]
Assets:
Other investments	0	0
Significant Unobservable Inputs (Level 3) [Member] | Foreign exchange contracts [Member]
Assets:
Derivatives	0	0
Liabilities:
Derivatives	$ 0	$ 0

Fair Value Measurements and F63

Fair Value Measurements and Financial Instruments - Schedule of financial instruments where the carrying amounts and fair values differ (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Fair value of financial instrument
Carrying value of total debt	$ 5,902	$ 5,138
Fair value of total debt	$ 6,178	$ 5,386

Commitments and Contingencies (

Commitments and Contingencies (Details) £ in Millions, NZD in Millions

Mar. 31, 2016USD ($)

Jun. 29, 2015NZD

Jan. 26, 2015CHF (SFr)

Jan. 26, 2015USD ($)

Dec. 02, 2014CHF (SFr)

Dec. 02, 2014USD ($)

Jan. 02, 2014GBP (£)

Sep. 14, 2010USD ($)

Jun. 01, 2007CHF (SFr)

Jun. 01, 2007USD ($)

Aug. 31, 2015USD ($)

Jun. 30, 2015GBP (£)

Mar. 31, 2015USD ($)

Dec. 31, 2014CHF (SFr)

Dec. 31, 2014USD ($)

Mar. 31, 2016USD ($)

Dec. 31, 2015USD ($)

Apr. 30, 2014GBP (£)

Legal, Guarantees and Indemnifications

Range of possible loss, minimum

$ 0

$ 0

Range of possible loss, maximum

300,000,000

300,000,000

Letters of credit outstanding

82,000,000

82,000,000

$ 58,000,000

Maximum potential funding under commitments

75,000,000

75,000,000

104,000,000

Potential Claim for Pension Advisory Services [Member]

Legal, Guarantees and Indemnifications

Estimate of possible loss

64,000,000

64,000,000

£ 45

Commitments to fund certain limited partnerships or subsidiaries [Member]

Legal, Guarantees and Indemnifications

Maximum potential funding under commitments

12,000,000

12,000,000

$ 12,000,000

Opry Mills Mall Limited Partnership [Member]

Legal, Guarantees and Indemnifications

Damages sought

$ 200,000,000

Amount of coverage for damages contended by the insurers

50,000,000

Difference amount of damages sought by the client

$ 150,000,000

Damages awarded

$ 204,000,000

$ 200,000,000

Philips [Member]

Legal, Guarantees and Indemnifications

Damages sought

410,000,000

£ 189

£ 290

$ 267,000,000

International Road Transport Union [Member] | Litigation Award [Member]

Legal, Guarantees and Indemnifications

Damages sought

47,000,000

SFr 46,000,000

Damages awarded

29,000,000

SFr 27,900,000

Damages awarded excluding interest and costs

17,000,000

SFr 16,800,000

Case settlement amount

13,000,000

SFr 12,800,000

Settlement, maximum liability

9,000,000

SFr 8,700,000

International Road Transport Union [Member] | Litigation USD Denominated Award [Member]

Legal, Guarantees and Indemnifications

Damages sought

$ 3,000,000

Damages awarded

$ 5,000,000

Damages awarded excluding interest and costs

$ 3,100,000

Case settlement amount

$ 4,700,000

Settlement, maximum liability

$ 115,000

International Road Transport Union [Member] | Litigation Expenses and Interest [Member]

Legal, Guarantees and Indemnifications

Damages sought

$ 30,000,000

Pending Litigation [Member] | Lyttleton Port Company Limited [Member]

Legal, Guarantees and Indemnifications

Damages sought

$ 123,000,000

NZD 184

Segment Information (Details)

Segment Information (Details) $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)segment	Mar. 31, 2015USD ($)
Segment Reporting Information
Number of reportable segments | segment	2
Total revenue	$ 2,792	$ 2,847
Total commissions, fees and other revenue	2,787	2,842
Total fiduciary investment income	5	5
Operating income before income tax	450	441
Interest income	2	3
Interest expense	(69)	(65)
Other income	18	42
Income before income taxes	401	421
Risk and Insurance Brokerage Services [Member]
Segment Reporting Information
Total fiduciary investment income	5	5
Consulting [Member]
Segment Reporting Information
Total fiduciary investment income	0	0
Segment Reconciling Items [Member]
Segment Reporting Information
Operating income before income tax	(46)	(47)
Operating Segments [Member]
Segment Reporting Information
Operating income before income tax	496	488
Operating Segments [Member] | Risk and Insurance Brokerage Services [Member]
Segment Reporting Information
Total revenue	1,872	1,895
Total commissions, fees and other revenue	1,867	1,890
Operating income before income tax	429	412
Operating Segments [Member] | Consulting [Member]
Segment Reporting Information
Total revenue	930	970
Total commissions, fees and other revenue	930	970
Operating income before income tax	67	76
Intersegment elimination [Member]
Segment Reporting Information
Total revenue	(10)	(18)
Total commissions, fees and other revenue	(10)	(18)
Reinsurance Brokerage Revenues [Member] | Operating Segments [Member] | Risk and Insurance Brokerage Services [Member]
Segment Reporting Information
Total commissions, fees and other revenue	372	377
Retail Brokerage Revenues [Member] | Operating Segments [Member] | Risk and Insurance Brokerage Services [Member]
Segment Reporting Information
Total commissions, fees and other revenue	1,495	1,513
Intersubsegment Eliminations [Member] | Operating Segments [Member] | Consulting [Member]
Segment Reporting Information
Total commissions, fees and other revenue	(4)	(5)
Reportable Subsegments [Member] | Outsourcing Revenues [Member] | Operating Segments [Member] | Consulting [Member]
Segment Reporting Information
Total commissions, fees and other revenue	560	604
Reportable Subsegments [Member] | Consulting Services Revenues [Member] | Operating Segments [Member] | Consulting [Member]
Segment Reporting Information
Total commissions, fees and other revenue	$ 374	$ 371

Guarantee of Registered Secur66

Guarantee of Registered Securities (Narrative) (Details)	Mar. 31, 2016	Mar. 01, 2016
Aon plc [Member]
Condensed Financial Statements, Captions [Line Items]
Parent company's percentage ownership of guarantors	100.00%
3.125% Senior notes due 2016 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt interest rate percentage (as a percent)	3.125%
5.00% Senior notes due September 2020 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt interest rate percentage (as a percent)	5.00%
8.205% Junior subordinated deferrable interest debentures due January 2027 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt interest rate percentage (as a percent)	8.205%
6.25% Senior notes due September 2040 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt interest rate percentage (as a percent)	6.25%
4.250% Senior notes due 2042 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt interest rate percentage (as a percent)	4.25%
4.45% notes due 2043 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt interest rate percentage (as a percent)	4.45%
4.00% notes due 2023 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt interest rate percentage (as a percent)	4.00%
2.875% notes due 2026 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt interest rate percentage (as a percent)	2.875%
3.50% Notes due June 2024 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt interest rate percentage (as a percent)	3.50%
4.60% notes due May 2044 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt interest rate percentage (as a percent)	4.60%
4.75% Notes Due May 2045 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt interest rate percentage (as a percent)	4.75%
3.50% notes due 2024 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt interest rate percentage (as a percent)	3.50%
4.60% notes due 2044 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt interest rate percentage (as a percent)	4.60%
4.75% Notes Due 2045 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt interest rate percentage (as a percent)	4.75%
Two Point Eight Zero Percent Senior Notes Due Twenty Twenty One [Member] | Senior Notes [Member]
Condensed Financial Statements, Captions [Line Items]
Debt interest rate percentage (as a percent)	2.80%
3.875% due in December 2025 [Member] | Senior Notes [Member]
Condensed Financial Statements, Captions [Line Items]
Debt interest rate percentage (as a percent)	3.875%	3.875%

Guarantee of Registered Secur67

Guarantee of Registered Securities - Condensed Consolidating Statement of Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Revenue
Commissions, fees and other	$ 2,787	$ 2,842
Fiduciary investment income	5	5
Total revenue	2,792	2,847
Expenses
Compensation and benefits	1,649	1,683
Other general expenses	693	723
Total operating expenses	2,342	2,406
Operating income	450	441
Interest income	2	3
Interest expense	(69)	(65)
Intercompany interest income (expense)	0	0
Intercompany other (expense) income	0	0
Other income	18	42
Income before income taxes	401	421
Income tax (benefit) expense	74	80
(Loss) income before equity in earnings of subsidiaries	327	341
Equity in earnings of subsidiaries, net of tax	0	0
Net income	327	341
Less: Net income attributable to noncontrolling interests	12	13
Net income attributable to Aon shareholders	315	328
Aon plc [Member]
Revenue
Commissions, fees and other	0	0
Fiduciary investment income	0	0
Total revenue	0	0
Expenses
Compensation and benefits	43	52
Other general expenses	7	13
Total operating expenses	50	65
Operating income	(50)	(65)
Interest income	(7)	(5)
Interest expense	(38)	(25)
Intercompany interest income (expense)	4	119
Intercompany other (expense) income	(54)	(50)
Other income	0	2
Income before income taxes	(145)	(24)
Income tax (benefit) expense	(26)	(5)
(Loss) income before equity in earnings of subsidiaries	(119)	(19)
Equity in earnings of subsidiaries, net of tax	434	347
Net income	315	328
Less: Net income attributable to noncontrolling interests	0	0
Net income attributable to Aon shareholders	315	328
Aon Corporation [Member]
Revenue
Commissions, fees and other	0	0
Fiduciary investment income	0	0
Total revenue	0	0
Expenses
Compensation and benefits	3	11
Other general expenses	2	2
Total operating expenses	5	13
Operating income	(5)	(13)
Interest income	5	3
Interest expense	(28)	(34)
Intercompany interest income (expense)	(133)	(105)
Intercompany other (expense) income	1	(8)
Other income	(5)	8
Income before income taxes	(165)	(149)
Income tax (benefit) expense	(62)	(50)
(Loss) income before equity in earnings of subsidiaries	(103)	(99)
Equity in earnings of subsidiaries, net of tax	367	403
Net income	264	304
Less: Net income attributable to noncontrolling interests	0	0
Net income attributable to Aon shareholders	264	304
Other Non-Guarantor Subsidiaries [Member]
Revenue
Commissions, fees and other	2,787	2,842
Fiduciary investment income	5	5
Total revenue	2,792	2,847
Expenses
Compensation and benefits	1,603	1,620
Other general expenses	684	708
Total operating expenses	2,287	2,328
Operating income	505	519
Interest income	4	5
Interest expense	(3)	(6)
Intercompany interest income (expense)	129	(14)
Intercompany other (expense) income	53	58
Other income	23	32
Income before income taxes	711	594
Income tax (benefit) expense	162	135
(Loss) income before equity in earnings of subsidiaries	549	459
Equity in earnings of subsidiaries, net of tax	264	304
Net income	813	763
Less: Net income attributable to noncontrolling interests	12	13
Net income attributable to Aon shareholders	801	750
Consolidating Adjustments [Member]
Revenue
Commissions, fees and other	0	0
Fiduciary investment income	0	0
Total revenue	0	0
Expenses
Compensation and benefits	0	0
Other general expenses	0	0
Total operating expenses	0	0
Operating income	0	0
Interest income	0	0
Interest expense	0	0
Intercompany interest income (expense)	0	0
Intercompany other (expense) income	0	0
Other income	0	0
Income before income taxes	0	0
Income tax (benefit) expense	0	0
(Loss) income before equity in earnings of subsidiaries	0	0
Equity in earnings of subsidiaries, net of tax	(1,065)	(1,054)
Net income	(1,065)	(1,054)
Less: Net income attributable to noncontrolling interests	0	0
Net income attributable to Aon shareholders	$ (1,065)	$ (1,054)

Guarantee of Registered Secur68

Guarantee of Registered Securities - Condensed Consolidating Statement of Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Net income	$ 327	$ 341
Less: Net income attributable to noncontrolling interests	12	13
Net income attributable to Aon shareholders	315	328
Change in fair value of financial instruments	(7)	5
Foreign currency translation adjustments	(79)	(322)
Post-retirement benefit obligation	(201)	23
Total other comprehensive (loss)	(287)	(294)
Equity in other comprehensive loss of subsidiaries, net of tax	0	0
Less: Other comprehensive (loss) income attributable to noncontrolling interests	0	(1)
Total other comprehensive (loss) attributable to Aon shareholders	(287)	(293)
Comprehensive income attributable to Aon shareholders	28	35
Aon plc [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	315	328
Less: Net income attributable to noncontrolling interests	0	0
Net income attributable to Aon shareholders	315	328
Change in fair value of financial instruments	0	0
Foreign currency translation adjustments	0	0
Post-retirement benefit obligation	0	0
Total other comprehensive (loss)	0	0
Equity in other comprehensive loss of subsidiaries, net of tax	(287)	(293)
Less: Other comprehensive (loss) income attributable to noncontrolling interests	0	0
Total other comprehensive (loss) attributable to Aon shareholders	(287)	(293)
Comprehensive income attributable to Aon shareholders	28	35
Aon Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	264	304
Less: Net income attributable to noncontrolling interests	0	0
Net income attributable to Aon shareholders	264	304
Change in fair value of financial instruments	(2)	(1)
Foreign currency translation adjustments	11	(23)
Post-retirement benefit obligation	13	8
Total other comprehensive (loss)	22	(16)
Equity in other comprehensive loss of subsidiaries, net of tax	(314)	(267)
Less: Other comprehensive (loss) income attributable to noncontrolling interests	0	0
Total other comprehensive (loss) attributable to Aon shareholders	(292)	(283)
Comprehensive income attributable to Aon shareholders	(28)	21
Other Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	813	763
Less: Net income attributable to noncontrolling interests	12	13
Net income attributable to Aon shareholders	801	750
Change in fair value of financial instruments	(5)	6
Foreign currency translation adjustments	(90)	(299)
Post-retirement benefit obligation	(214)	15
Total other comprehensive (loss)	(309)	(278)
Equity in other comprehensive loss of subsidiaries, net of tax	(292)	(283)
Less: Other comprehensive (loss) income attributable to noncontrolling interests	0	(1)
Total other comprehensive (loss) attributable to Aon shareholders	(601)	(560)
Comprehensive income attributable to Aon shareholders	200	190
Consolidating Adjustments [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	(1,065)	(1,054)
Less: Net income attributable to noncontrolling interests	0	0
Net income attributable to Aon shareholders	(1,065)	(1,054)
Change in fair value of financial instruments	0	0
Foreign currency translation adjustments	0	0
Post-retirement benefit obligation	0	0
Total other comprehensive (loss)	0	0
Equity in other comprehensive loss of subsidiaries, net of tax	893	843
Less: Other comprehensive (loss) income attributable to noncontrolling interests	0	0
Total other comprehensive (loss) attributable to Aon shareholders	893	843
Comprehensive income attributable to Aon shareholders	$ (172)	$ (211)

Guarantee of Registered Secur69

Guarantee of Registered Securities - Condensed Consolidating Statement of Financial Position (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
CURRENT ASSETS :
Cash and cash equivalents	$ 465	$ 384	$ 378	$ 374
Short-term investments	587	356
Receivables, net	2,591	2,734
Fiduciary assets	9,776	9,932
Intercompany receivables	0	0
Other current assets	622	562
Total Current Assets	14,041	13,968
Goodwill	8,411	8,448
Intangible assets, net	2,108	2,180
Fixed assets, net	766	765
Intercompany receivables	0	0
Non-current deferred tax assets	171	141
Prepaid pension	737	1,033
Other non-current assets	579	592
Investment in subsidiary	0	0
TOTAL ASSETS	26,813	27,127
CURRENT LIABILITIES
Accounts payable and accrued liabilities	9,776	9,932
Short-term debt and current portion of long-term debt	695	562
Accounts payable and accrued liabilities	1,420	1,772
Intercompany payables	0	0
Other current liabilities	902	820
Total Current Liabilities	12,793	13,086
Long-term debt	5,902	5,138
Non-current deferred tax liabilities	177	176
Pension, other post-retirement and post-employment liabilities	1,756	1,795
Intercompany payables	0	0
Other non-current liabilities	838	769
TOTAL LIABILITIES	21,466	20,964
TOTAL AON SHAREHOLDERS' EQUITY	5,281	6,106
Noncontrolling interests	66	57
TOTAL EQUITY	5,347	6,163
TOTAL LIABILITIES AND EQUITY	26,813	27,127
Aon plc [Member]
CURRENT ASSETS :
Cash and cash equivalents	0	0	0	0
Short-term investments	0	0
Receivables, net	2	1
Fiduciary assets	0	0
Intercompany receivables	43	432
Other current assets	0	0
Total Current Assets	45	433
Goodwill	0	0
Intangible assets, net	0	0
Fixed assets, net	0	0
Intercompany receivables	379	375
Non-current deferred tax assets	154	154
Prepaid pension	0	0
Other non-current assets	0	0
Investment in subsidiary	11,949	11,804
TOTAL ASSETS	12,527	12,766
CURRENT LIABILITIES
Accounts payable and accrued liabilities	0	0
Short-term debt and current portion of long-term debt	184	0
Accounts payable and accrued liabilities	2,624	2,988
Intercompany payables	141	167
Other current liabilities	85	47
Total Current Liabilities	3,034	3,202
Long-term debt	4,206	3,451
Non-current deferred tax liabilities	0	0
Pension, other post-retirement and post-employment liabilities	0	0
Intercompany payables	0	0
Other non-current liabilities	6	7
TOTAL LIABILITIES	7,246	6,660
TOTAL AON SHAREHOLDERS' EQUITY	5,281	6,106
Noncontrolling interests	0	0
TOTAL EQUITY	5,281	6,106
TOTAL LIABILITIES AND EQUITY	12,527	12,766
Aon Corporation [Member]
CURRENT ASSETS :
Cash and cash equivalents	1,537	2,083	2,230	2,727
Short-term investments	453	209
Receivables, net	0	0
Fiduciary assets	0	0
Intercompany receivables	3,786	1,950
Other current assets	206	217
Total Current Assets	5,982	4,459
Goodwill	0	0
Intangible assets, net	0	0
Fixed assets, net	0	0
Intercompany receivables	537	526
Non-current deferred tax assets	556	558
Prepaid pension	6	6
Other non-current assets	114	119
Investment in subsidiary	16,643	16,534
TOTAL ASSETS	23,838	22,202
CURRENT LIABILITIES
Accounts payable and accrued liabilities	0	0
Short-term debt and current portion of long-term debt	500	550
Accounts payable and accrued liabilities	22	45
Intercompany payables	11,365	9,518
Other current liabilities	60	56
Total Current Liabilities	11,947	10,169
Long-term debt	1,413	1,412
Non-current deferred tax liabilities	0	0
Pension, other post-retirement and post-employment liabilities	1,295	1,313
Intercompany payables	8,881	8,799
Other non-current liabilities	63	140
TOTAL LIABILITIES	23,599	21,833
TOTAL AON SHAREHOLDERS' EQUITY	239	369
Noncontrolling interests	0	0
TOTAL EQUITY	239	369
TOTAL LIABILITIES AND EQUITY	23,838	22,202
Other Non-Guarantor Subsidiaries [Member]
CURRENT ASSETS :
Cash and cash equivalents	1,457	1,242	650	1,361
Short-term investments	134	147
Receivables, net	2,589	2,733
Fiduciary assets	9,776	9,932
Intercompany receivables	8,759	7,957
Other current assets	418	347
Total Current Assets	23,133	22,358
Goodwill	8,411	8,448
Intangible assets, net	2,108	2,180
Fixed assets, net	766	765
Intercompany receivables	8,716	8,633
Non-current deferred tax assets	137	107
Prepaid pension	731	1,027
Other non-current assets	465	557
Investment in subsidiary	239	369
TOTAL ASSETS	44,706	44,444
CURRENT LIABILITIES
Accounts payable and accrued liabilities	9,776	9,932
Short-term debt and current portion of long-term debt	11	12
Accounts payable and accrued liabilities	1,303	1,680
Intercompany payables	1,082	654
Other current liabilities	759	720
Total Current Liabilities	12,931	12,998
Long-term debt	283	275
Non-current deferred tax liabilities	853	854
Pension, other post-retirement and post-employment liabilities	461	482
Intercompany payables	751	735
Other non-current liabilities	769	705
TOTAL LIABILITIES	16,048	16,049
TOTAL AON SHAREHOLDERS' EQUITY	28,592	28,338
Noncontrolling interests	66	57
TOTAL EQUITY	28,658	28,395
TOTAL LIABILITIES AND EQUITY	44,706	44,444
Consolidating Adjustments [Member]
CURRENT ASSETS :
Cash and cash equivalents	(2,529)	(2,941)	$ (2,502)	$ (3,714)
Short-term investments	0	0
Receivables, net	0	0
Fiduciary assets	0	0
Intercompany receivables	(12,588)	(10,339)
Other current assets	(2)	(2)
Total Current Assets	(15,119)	(13,282)
Goodwill	0	0
Intangible assets, net	0	0
Fixed assets, net	0	0
Intercompany receivables	(9,632)	(9,534)
Non-current deferred tax assets	(676)	(678)
Prepaid pension	0	0
Other non-current assets	0	(84)
Investment in subsidiary	(28,831)	(28,707)
TOTAL ASSETS	(54,258)	(52,285)
CURRENT LIABILITIES
Accounts payable and accrued liabilities	0	0
Short-term debt and current portion of long-term debt	0	0
Accounts payable and accrued liabilities	(2,529)	(2,941)
Intercompany payables	(12,588)	(10,339)
Other current liabilities	(2)	(3)
Total Current Liabilities	(15,119)	(13,283)
Long-term debt	0	0
Non-current deferred tax liabilities	(676)	(678)
Pension, other post-retirement and post-employment liabilities	0	0
Intercompany payables	(9,632)	(9,534)
Other non-current liabilities	0	(83)
TOTAL LIABILITIES	(25,427)	(23,578)
TOTAL AON SHAREHOLDERS' EQUITY	(28,831)	(28,707)
Noncontrolling interests	0	0
TOTAL EQUITY	(28,831)	(28,707)
TOTAL LIABILITIES AND EQUITY	$ (54,258)	$ (52,285)

Guarantee of Registered Secur70

Guarantee of Registered Securities - Condensed Consolidating Statement of Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES
CASH PROVIDED BY (USED FOR) OPERATING ACTIVITIES	$ 273	$ 298
CASH FLOWS FROM INVESTING ACTIVITIES
Proceeds from investments	13	3
Purchases of investments	(14)	(1)
Net sales of short-term investments - non-fiduciary	(227)	42
Acquisition of businesses, net of cash acquired	(16)	(21)
Proceeds from sale of businesses	97	41
Capital expenditures	(52)	(62)
CASH (USED FOR) PROVIDED BY INVESTING ACTIVITIES	(199)	2
CASH FLOWS FROM FINANCING ACTIVITIES
Share repurchase	(685)	(250)
Advances from (to) affiliates	0	0
Issuance of shares for employee benefit plans	(65)	(114)
Issuance of debt	1,045	870
Repayment of debt	(175)	(686)
Cash dividends to shareholders	(82)	(71)
Noncontrolling interests and other financing activities	(42)	(6)
CASH USED FOR FINANCING ACTIVITIES	(4)	(257)
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	11	(39)
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	81	4
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	384	374
CASH AND CASH EQUIVALENTS AT END OF PERIOD	465	378
Aon plc [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
CASH PROVIDED BY (USED FOR) OPERATING ACTIVITIES	(47)	164
CASH FLOWS FROM INVESTING ACTIVITIES
Proceeds from investments	0	0
Purchases of investments	0	0
Net sales of short-term investments - non-fiduciary	0	0
Acquisition of businesses, net of cash acquired	0	0
Proceeds from sale of businesses	0	0
Capital expenditures	0	0
CASH (USED FOR) PROVIDED BY INVESTING ACTIVITIES	0	0
CASH FLOWS FROM FINANCING ACTIVITIES
Share repurchase	(685)	(250)
Advances from (to) affiliates	(46)	157
Issuance of shares for employee benefit plans	(64)	(114)
Issuance of debt	996	114
Repayment of debt	(72)	0
Cash dividends to shareholders	(82)	(71)
Noncontrolling interests and other financing activities	0	0
CASH USED FOR FINANCING ACTIVITIES	47	(164)
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	0	0
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	0	0
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	0	0
CASH AND CASH EQUIVALENTS AT END OF PERIOD	0	0
Aon Corporation [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
CASH PROVIDED BY (USED FOR) OPERATING ACTIVITIES	(37)	(188)
CASH FLOWS FROM INVESTING ACTIVITIES
Proceeds from investments	9	0
Purchases of investments	(5)	(1)
Net sales of short-term investments - non-fiduciary	(244)	(1)
Acquisition of businesses, net of cash acquired	0	0
Proceeds from sale of businesses	0	0
Capital expenditures	0	0
CASH (USED FOR) PROVIDED BY INVESTING ACTIVITIES	(240)	(2)
CASH FLOWS FROM FINANCING ACTIVITIES
Share repurchase	0	0
Advances from (to) affiliates	(219)	(385)
Issuance of shares for employee benefit plans	0	0
Issuance of debt	50	756
Repayment of debt	(100)	(678)
Cash dividends to shareholders	0	0
Noncontrolling interests and other financing activities	0	0
CASH USED FOR FINANCING ACTIVITIES	(269)	(307)
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	0	0
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(546)	(497)
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	2,083	2,727
CASH AND CASH EQUIVALENTS AT END OF PERIOD	1,537	2,230
Other Non-Guarantor Subsidiaries [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
CASH PROVIDED BY (USED FOR) OPERATING ACTIVITIES	357	322
CASH FLOWS FROM INVESTING ACTIVITIES
Proceeds from investments	4	3
Purchases of investments	(9)	0
Net sales of short-term investments - non-fiduciary	17	43
Acquisition of businesses, net of cash acquired	(16)	(21)
Proceeds from sale of businesses	97	41
Capital expenditures	(52)	(62)
CASH (USED FOR) PROVIDED BY INVESTING ACTIVITIES	41	4
CASH FLOWS FROM FINANCING ACTIVITIES
Share repurchase	0	0
Advances from (to) affiliates	(147)	(984)
Issuance of shares for employee benefit plans	(1)	0
Issuance of debt	(1)	0
Repayment of debt	(3)	(8)
Cash dividends to shareholders	0	0
Noncontrolling interests and other financing activities	(42)	(6)
CASH USED FOR FINANCING ACTIVITIES	(194)	(998)
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	11	(39)
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	215	(711)
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	1,242	1,361
CASH AND CASH EQUIVALENTS AT END OF PERIOD	1,457	650
Consolidating Adjustments [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
CASH PROVIDED BY (USED FOR) OPERATING ACTIVITIES	0	0
CASH FLOWS FROM INVESTING ACTIVITIES
Proceeds from investments	0	0
Purchases of investments	0	0
Net sales of short-term investments - non-fiduciary	0	0
Acquisition of businesses, net of cash acquired	0	0
Proceeds from sale of businesses	0	0
Capital expenditures	0	0
CASH (USED FOR) PROVIDED BY INVESTING ACTIVITIES	0	0
CASH FLOWS FROM FINANCING ACTIVITIES
Share repurchase	0	0
Advances from (to) affiliates	412	1,212
Issuance of shares for employee benefit plans	0	0
Issuance of debt	0	0
Repayment of debt	0	0
Cash dividends to shareholders	0	0
Noncontrolling interests and other financing activities	0	0
CASH USED FOR FINANCING ACTIVITIES	412	1,212
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	0	0
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	412	1,212
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	(2,941)	(3,714)
CASH AND CASH EQUIVALENTS AT END OF PERIOD	$ (2,529)	$ (2,502)