Arthur J. Gallagher & Co. (AJG) 10-K 13 Feb 17 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2016	Jan. 31, 2017	Jun. 30, 2016
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY
Trading Symbol	AJG
Entity Registrant Name	GALLAGHER ARTHUR J & CO
Entity Central Index Key	354,190
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		178,617,000
Entity Public Float			$ 7,533,668,000

Consolidated Statement of Earni

Consolidated Statement of Earnings - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Commissions	$ 2,439.1	$ 2,338.7	$ 2,083
Fees	1,492.8	1,432.3	1,258.3
Supplemental commissions	147	125.5	104
Contingent commissions	107.2	93.7	84.7
Investment income	53.3	54.2	41.3
Gains on books of business sales	6.6	6.7	7.3
Revenues from clean coal activities	1,350.1	1,310.8	1,029.5
Other net revenues	(1.3)	30.5	18.4
Total revenues	5,594.8	5,392.4	4,626.5
Compensation	2,538.9	2,428.9	2,167.6
Operating	797.7	840.7	743.1
Cost of revenues from clean coal activities	1,408.6	1,351.5	1,058.9
Interest	109.8	103	89
Depreciation	103.6	93.9	69.4
Amortization	247.2	240.3	189.5
Change in estimated acquisition earnout payables	32.1	40.6	17.5
Total expenses	5,237.9	5,098.9	4,335
Earnings before income taxes	356.9	293.5	291.5
Benefit for income taxes	(88.1)	(95.6)	(36)
Net earnings	445	389.1	327.5
Net earnings attributable to noncontrolling interests	30.6	32.3	24.1
Net earnings attributable to controlling interests	$ 414.4	$ 356.8	$ 303.4
Basic net earnings per share:	$ 2.33	$ 2.07	$ 1.98
Diluted net earnings per share:	2.32	2.06	1.97
Dividends declared per common share	$ 1.52	$ 1.48	$ 1.44

Consolidated Statement of Compr

Consolidated Statement of Comprehensive Earnings - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net earnings	$ 445	$ 389.1	$ 327.5
Change in pension liability, net of taxes	(4.4)	1.3	(18.6)
Foreign currency translation	(231.8)	(261.1)	(238.4)
Change in fair value of derivative instruments, net of taxes	(4.9)	(2.1)	(1)
Comprehensive earnings	203.9	127.2	69.5
Comprehensive earnings attributable to noncontrolling interests	35.1	25.9	31.5
Comprehensive earnings attributable to controlling interests	$ 168.8	$ 101.3	$ 38

Consolidated Balance Sheet

Consolidated Balance Sheet - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Cash and cash equivalents	$ 545.5	$ 480.4
Restricted cash	1,392.1	1,412.1
Premiums and fees receivable	1,844.8	1,734
Other current assets	633.7	587.2
Total current assets	4,416.1	4,213.7
Fixed assets - net	377.6	249
Deferred income taxes	796.5	643.5
Other noncurrent assets	504.3	442.6
Goodwill - net	3,767.8	3,662.9
Amortizable intangible assets - net	1,627.3	1,698.8
Total assets	11,489.6	10,910.5
Premiums payable to insurance and reinsurance companies	2,996.1	2,877.1
Accrued compensation and other accrued liabilities	772.1	812.7
Unearned fees	69	61.3
Other current liabilities	70.9	54
Premium financing borrowings	125.6	137
Corporate related borrowings - current	578	245
Total current liabilities	4,611.7	4,187.1
Corporate related borrowings - noncurrent	2,144.6	2,071.7
Other noncurrent liabilities	1,077.5	963.5
Total liabilities	7,833.8	7,222.3
Stockholders' equity:
Common stock - authorized 400.0 shares; issued and outstanding 178.3 shares in 2016 and 176.9 shares in 2015	178.3	176.9
Capital in excess of par value	3,265.5	3,209.4
Retained earnings	916.4	774.5
Accumulated other comprehensive loss	(763.6)	(522.5)
Stockholders' equity attributable to controlling interests	3,596.6	3,638.3
Stockholders' equity attributable to noncontrolling interests	59.2	49.9
Total stockholders' equity	3,655.8	3,688.2
Total liabilities and stockholders' equity	$ 11,489.6	$ 10,910.5

Consolidated Balance Sheet (Par

Consolidated Balance Sheet (Parenthetical) - shares	Dec. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Common stock - authorized shares	400,000,000	400,000,000
Common stock - issued shares	178,300,000	176,900,000
Common stock - outstanding shares	178,300,000	176,900,000

Consolidated Statement of Cash

Consolidated Statement of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net earnings	$ 445	$ 389.1	$ 327.5
Adjustments to reconcile net earnings to net cash provided by operating activities:
Net gain on investments and other	(6.5)	(6.6)	(23)
Depreciation and amortization	350.8	334.2	258.9
Change in estimated acquisition earnout payables	32.1	40.6	17.5
Amortization of deferred compensation and restricted stock	28.5	22.7	22.9
Stock-based and other noncash compensation expense	14.7	11.2	10.6
Effect of changes in foreign exchange rate	(3)	(0.2)	(0.5)
Net change in restricted cash	(50.3)	(45.6)	(62.1)
Net change in premiums receivable	(242.8)	(209.3)	95.3
Net change in premiums payable	352.9	406.6	60
Net change in other current assets	(55.2)	(34.7)	(150.5)
Net change in accrued compensation and other accrued liabilities	69.1	217.8	191.6
Net change in fees receivable/unearned fees	2.8	(49.6)	(26)
Net change in income taxes payable	(10.8)	(18.5)	4.9
Net change in deferred income taxes	(158)	(161.2)	(126.1)
Net change in other noncurrent assets and liabilities	(34.5)	(89.5)	(22.9)
Unrealized foreign currency remeasurement loss	(112.7)	(154.4)	(141.5)
Net cash provided by operating activities	622.1	652.6	436.6
Cash flows from investing activities:
Net additions to fixed assets	(217.8)	(99)	(81.5)
Cash paid for acquisitions, net of cash acquired	(327.3)	(342.3)	(1,918.3)
Net proceeds from sales of operations/books of business	7.8	9.2	8.2
Net funding of investment transactions	(31.9)	(29.5)	(20.1)
Net cash used by investing activities	(569.2)	(461.6)	(2,011.7)
Cash flows from financing activities:
Proceeds from issuance of common stock	45.6	203.3	997
Tax impact from issuance of common stock	6.5	5.3	6.9
Repurchases of common stock	(101)
Payments to noncontrolling interests	(41.8)	(39.9)	(34.3)
Dividends paid	(272.2)	(257.5)	(223.1)
Net borrowings on premium financing debt facility	(12.2)	23.9	7.5
Borrowings on line of credit facilities	2,740	849	1,109.9
Repayments on line of credit facilities	(2,657)	(794)	(1,500.4)
Borrowings of corporate related long-term debt	376		1,300
Repayments of corporate related long-term debt	(50)		(100)
Net cash provided (used) by financing activities	33.9	(9.9)	1,563.5
Effect of changes in foreign exchange rates on cash and cash equivalents	(21.7)	(15.1)	27.9
Net increase in cash and cash equivalents	65.1	166	16.3
Cash and cash equivalents at beginning of year	480.4	314.4	298.1
Cash and cash equivalents at end of year	545.5	480.4	314.4
Supplemental disclosures of cash flow information:
Interest paid	112.8	103.9	82.5
Income taxes paid	$ 66.1	$ 78.3	$ 72.9

Consolidated Statement of Stock

Consolidated Statement of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Capital in Excess of Par Value [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Earnings (Loss) [Member]	Noncontrolling Interests [Member]
Beginning Balance at Dec. 31, 2013	$ 2,114.8	$ 133.6	$ 1,358.1	$ 596.4	$ (2.6)	$ 29.3
Beginning Balance (in shares) at Dec. 31, 2013		133.6
Net earnings	327.5			303.4		24.1
Net purchase of subsidiary shares from noncontrolling interests	49.3					49.3
Dividends paid to noncontrolling interests	(34.4)					(34.4)
Net change in pension asset/liability, net of taxes	(18.6)				(18.6)
Foreign currency translation	(231)				(238.4)	7.4
Change in fair value of derivative instruments, net of taxes	(1)				(1)
Compensation expense related to stock option plan grants	9.5		9.5
Tax impact from issuance of common stock	6.9		6.9
Common stock issued in:
Purchase transactions	299.3	$ 6.5	292.8
Purchase transactions (in shares)		6.5
Stock option plans	$ 44.2	$ 1.6	42.6
Stock option plans (in shares)	1.6	1.6
Employee stock purchase plan	$ 12.4	$ 0.3	12.1
Employee stock purchase plan (in shares)		0.3
Deferred compensation and restricted stock	8.5	$ 0.1	8.4
Deferred compensation and restricted stock (in shares)		0.1
Stock issuance under dribble-out program	29	$ 0.6	28.4
Stock issuance under dribble-out program (in shares)		0.6
Stock issuance from public offering	911.4	$ 21.9	889.5
Stock issuance from public offering (in shares)		21.9
Other compensation expense	1.1		1.1
Cash dividends declared on common stock	(223.8)			(223.8)
Ending Balance at Dec. 31, 2014	3,305.1	$ 164.6	2,649.4	676	(260.6)	75.7
Ending Balance (in shares) at Dec. 31, 2014		164.6
Net earnings	389.1			356.8		32.3
Net purchase of subsidiary shares from noncontrolling interests	(15)					(15)
Dividends paid to noncontrolling interests	(36.7)					(36.7)
Net change in pension asset/liability, net of taxes	1.3				1.3
Foreign currency translation	(267.5)				(261.1)	(6.4)
Change in fair value of derivative instruments, net of taxes	(2.1)				(2.1)
Compensation expense related to stock option plan grants	11.2		11.2
Tax impact from issuance of common stock	5.3		5.3
Common stock issued in:
Purchase transactions	346.2	$ 7.3	338.9
Purchase transactions (in shares)		7.3
Stock option plans	$ 40.4	$ 1.4	39
Stock option plans (in shares)	1.4	1.4
Employee stock purchase plan	$ 13.8	$ 0.3	13.5
Employee stock purchase plan (in shares)		0.3
Deferred compensation and restricted stock	6.2	$ 0.2	6
Deferred compensation and restricted stock (in shares)		0.2
Stock issuance under dribble-out program	149.2	$ 3.1	146.1
Stock issuance under dribble-out program (in shares)		3.1
Cash dividends declared on common stock	(258.3)			(258.3)
Ending Balance at Dec. 31, 2015	3,688.2	$ 176.9	3,209.4	774.5	(522.5)	49.9
Ending Balance (in shares) at Dec. 31, 2015		176.9
Net earnings	445			414.4		30.6
Net purchase of subsidiary shares from noncontrolling interests	8.3					8.3
Dividends paid to noncontrolling interests	(34.1)					(34.1)
Net change in pension asset/liability, net of taxes	(4.4)				(4.4)
Foreign currency translation	(227.3)				(231.8)	4.5
Change in fair value of derivative instruments, net of taxes	(4.9)				(4.9)
Compensation expense related to stock option plan grants	14.7		14.7
Tax impact from issuance of common stock	6.5		6.5
Common stock issued in:
Purchase transactions	91.6	$ 2	89.6
Purchase transactions (in shares)		2
Stock option plans	$ 29.7	$ 1.1	28.6
Stock option plans (in shares)	1.1	1.1
Employee stock purchase plan	$ 15.9	$ 0.4	15.5
Employee stock purchase plan (in shares)		0.4
Deferred compensation and restricted stock	0.1	$ 0.2	(0.1)
Deferred compensation and restricted stock (in shares)		0.2
Common stock repurchases	(101)	$ (2.3)	(98.7)
Common stock repurchases (in shares)		(2.3)
Cash dividends declared on common stock	(272.5)			(272.5)
Ending Balance at Dec. 31, 2016	$ 3,655.8	$ 178.3	$ 3,265.5	$ 916.4	$ (763.6)	$ 59.2
Ending Balance (in shares) at Dec. 31, 2016		178.3

Consolidated Statement of Stoc8

Consolidated Statement of Stockholders' Equity (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Stockholders' Equity [Abstract]
Tax effect on net change in pension asset/liability	$ (2.9)	$ 0.9	$ (12.4)
Net change in fair value of derivative instruments, tax	$ (3.2)	$ (1.4)	$ (0.7)

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	1. Summary of Significant Accounting Policies Nature of Operations - Basis of Presentation - In the preparation of our consolidated financial statements as of December 31, 2016, management evaluated all material subsequent events or transactions that occurred after the balance sheet date through the date on which the financial statements were issued for potential recognition in our consolidated financial statements and/or disclosure in the notes thereto. Use of Estimates Revenue Recognition We recognize commission revenues at the later of the billing or the effective date of the related insurance policies, net of an allowance for estimated policy cancellations. We recognize commission revenues related to installment premiums as the installments are billed. We recognize supplemental commission revenues using internal data and information received from insurance carriers that allows us to reasonably estimate the supplemental commissions earned in the period. A supplemental commission is a commission paid by an insurance carrier that is above the base commission paid, is determined by the insurance carrier, and is established annually in advance of the contractual period based on historical performance criteria. We recognize contingent commissions and commissions on premiums directly billed by insurance carriers as revenue when we have obtained the data necessary to reasonably determine such amounts. Typically, we cannot reasonably determine these types of commission revenues until we have received the cash or the related policy detail or other carrier specific information from the insurance carrier. A contingent commission is a commission paid by an insurance carrier based on the overall profit and/or volume of the business placed with that insurance carrier during a particular calendar year and is determined after the contractual period. Commissions on premiums billed directly by insurance carriers to the insureds generally relate to a large number of property/casualty insurance policy transactions, each with small premiums, and comprise a substantial portion of the revenues generated by our employee benefit brokerage operations. Under these direct bill arrangements, the insurance carrier controls the entire billing and policy issuance process. We record the income effects of subsequent premium adjustments when the adjustments become known. Fee revenues generated from the brokerage segment primarily relate to fees negotiated in lieu of commissions that we recognize in the same manner as commission revenues. Fee revenues generated from the risk management segment relate to third party claims administration, loss control and other risk management consulting services, which we provide over a period of time, typically one year. We recognize these fee revenues ratably as the services are rendered, and record the income effects of subsequent fee adjustments when the adjustments become known. We deduct brokerage expense from gross revenues in our determination of our total revenues. Brokerage expense represents commissions paid to sub-brokers Premiums and fees receivable in the accompanying consolidated balance sheet are net of allowances for estimated policy cancellations and doubtful accounts. The allowance for estimated policy cancellations was $7.1 million and $7.4 million at December 31, 2016 and 2015, respectively, which represents a reserve for future reversals in commission and fee revenues related to the potential cancellation of client insurance policies that were in force as of each year end. The allowance for doubtful accounts was $12.8 million and $13.3 million at December 31, 2016 and 2015, respectively. We establish the allowance for estimated policy cancellations through a charge to revenues and the allowance for doubtful accounts through a charge to operating expenses. Both of these allowances are based on estimates and assumptions using historical data to project future experience. Such estimates and assumptions could change in the future as more information becomes known which could impact the amounts reported and disclosed herein. We periodically review the adequacy of these allowances and make adjustments as necessary. Investment income primarily includes interest and dividend income (including interest income from our premium financing operations), which is accrued as it is earned. Gains on books of business sales represent one-time Claims Handling Obligations run-off Earnings per Share Cash and Cash Equivalents Restricted Cash Related to our third party administration business and in certain of our brokerage operations, we are responsible for client claim funds that we hold in a fiduciary capacity. We do not earn any interest income on the funds held. These client funds have been included in restricted cash, along with a corresponding liability in premiums payable to insurance and reinsurance companies in the accompanying consolidated balance sheet. Derivative Instruments Premium Financing Fixed Assets Useful Life Office equipment Three to ten years Furniture and fixtures Three to ten years Computer equipment Three to five years Building Fifteen to forty years Software Three to five years Refined fuel plants Ten years Leasehold improvements Shorter of the lease term or useful life of the asset Intangible Assets non-compete non-compete non-compete non-compete We review all of our intangible assets for impairment periodically (at least annually for goodwill) and whenever events or changes in business circumstances indicate that the carrying value of the assets may not be recoverable. We perform such impairment reviews at the division (i.e., reporting unit) level with respect to goodwill and at the business unit level for amortizable intangible assets. In reviewing intangible assets, if the fair value were less than the carrying amount of the respective (or underlying) asset, an indicator of impairment would exist and further analysis would be required to determine whether or not a loss would need to be charged against current period earnings as a component of amortization expense. Based on the results of impairment reviews in 2016, 2015 and 2014, we wrote off $1.8 million, $11.5 million and $1.8 million, respectively, of amortizable intangible assets primarily related to prior year acquisitions of our brokerage segment, which is included in amortization expense in the accompanying consolidated statement of earnings. The determinations of impairment indicators and fair value are based on estimates and assumptions related to the amount and timing of future cash flows and future interest rates. Such estimates and assumptions could change in the future as more information becomes known which could impact the amounts reported and disclosed herein. Income Taxes two-step Uncertain tax positions are measured based upon the facts and circumstances that exist at each reporting period and involve significant management judgment. Subsequent changes in judgment based upon new information may lead to changes in recognition, derecognition and measurement. Adjustments may result, for example, upon resolution of an issue with the taxing authorities, or expiration of a statute of limitations barring an assessment for an issue. We recognize interest and penalties, if any, related to unrecognized tax benefits in our provision for income taxes. Tax law requires certain items to be included in our tax returns at different times than such items are reflected in the financial statements. As a result, the annual tax expense reflected in our consolidated statements of earnings is different than that reported in our tax returns. Some of these differences are permanent, such as expenses that are not deductible in our tax returns, and some differences are temporary and reverse over time, such as depreciation expense and amortization expense deductible for income tax purposes. Temporary differences create deferred tax assets and liabilities. Deferred tax liabilities generally represent tax expense recognized in the financial statements for which a tax payment has been deferred, or expense which has been deducted in the tax return but has not yet been recognized in the financial statements. Deferred tax assets generally represent items that can be used as a tax deduction or credit in tax returns in future years for which a benefit has already been recorded in the financial statements. We establish or adjust valuation allowances for deferred tax assets when we estimate that it is more likely than not that future taxable income will be insufficient to fully use a deduction or credit in a specific jurisdiction. In assessing the need for the recognition of a valuation allowance for deferred tax assets, we consider whether it is more likely than not that some portion, or all, of the deferred tax assets will not be realized and adjust the valuation allowance accordingly. We evaluate all significant available positive and negative evidence as part of our analysis. Negative evidence includes the existence of losses in recent years. Positive evidence includes the forecast of future taxable income by jurisdiction, tax-planning Fair Value of Financial Instruments The classification of a financial instrument within the valuation hierarchy is based upon the transparency of inputs to the valuation of an asset or liability on the measurement date. The three levels of the hierarchy in order of priority of inputs to the valuation technique are defined as follows: • Level 1 - Valuations are based on unadjusted quoted prices in active markets for identical financial instruments; • Level 2 - Valuations are based on quoted market prices, other than quoted prices included in Level 1, in markets that are not active or on inputs that are observable either directly or indirectly for the full term of the financial instrument; and • Level 3 - Valuations are based on pricing or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement of the financial instrument. Such inputs may reflect management’s own assumptions about the assumptions a market participant would use in pricing the financial instrument. The level in the fair value hierarchy within which the fair value measurement is classified is determined based on the lowest level input that is significant to the fair value measure in its entirety. The carrying amounts of financial assets and liabilities reported in the accompanying consolidated balance sheet for cash and cash equivalents, restricted cash, premiums and fees receivable, premiums payable to insurance carriers, accrued salaries and bonuses, accounts payable and other accrued liabilities, unearned fees and income taxes payable, at December 31, 2016 and 2015, approximate fair value because of the short-term duration of these instruments. See Note 3 to our consolidated financial statements for the fair values related to the establishment of intangible assets and the establishment and adjustment of earnout payables. See Note 7 to our consolidated financial statements for the fair values related to borrowings outstanding at December 31, 2016 and 2015 under our debt agreements. See Note 12 to our consolidated financial statements for the fair values related to investments at December 31, 2016 and 2015 under our defined benefit pension plan. Litigation - Retention bonus arrangements Stock-Based Compensation - paid-in Cash-settled share-based payments to employees include awards under our Performance Unit Program and stock appreciation rights. The fair value of the amount payable to employees in respect of cash-settled share-based payments is recognized as compensation expense, with a corresponding increase in liabilities, over the vesting period. The liability is remeasured at each reporting date and at settlement date. Any changes in fair value of the liability are recognized as compensation expense. We recognize share-based compensation expense over the requisite service period for awards expected to ultimately vest. Forfeitures are estimated on the date of grant and revised if actual or expected forfeiture activity differs from original estimates. Employee Stock Purchase Plan Defined Benefit Pension and Other Postretirement Plans

Effect of New Accounting Pronou

Effect of New Accounting Pronouncements	12 Months Ended
	Dec. 31, 2016
Accounting Changes and Error Corrections [Abstract]
Effect of New Accounting Pronouncements	2. Effect of New Accounting Pronouncements Leases In February 2016, the Financial Accounting Standards Board (which we refer to as the FASB) issued Accounting Standards Update (which we refer to as ASU) 2016-02, right-of-use We anticipate this guidance will have a material impact on our consolidated financial statements. While we are continuing to assess all potential impacts of the new guidance, we currently believe the most significant impact relates to our real estate operating leases and the related recognition of right-of-use Stock Compensation In March 2016, the FASB issued ASU No. 2016-09, Improvements Cash Receipts and Cash Payments In August 2016, the FASB issued ASU No. 2016-15, (ASU 2016-15). ASU 2016-15 Consolidations In October 2016, the FASB issued ASU No. 2016-17, 2015-02, Income Taxes In October 2016, the FASB issued ASU No. 2016-16, Restricted Cash In November 2016, the FASB issued Accounting Standards Update 2016-18, Consolidations In February 2015, the FASB issued ASU No. 2015-02, re-evaluation Debt Issuance Costs In April 2015, the FASB issued ASU No. 2015-03, non-current - Intangibles - Goodwill and Other In April 2015, the FASB issued ASU No. 2015-05, Other—Internal-Use (Subtopic 350-40): internal-use Business Combinations In September 2015, the FASB issued ASU No. 2015-16, Income Taxes In November 2015, the FASB issued ASU No. 2015-17, ASU 2015-17 ASU 2015-17 Revenue Recognition In 2014, the FASB issued ASU No. 2014-09, pre-2018 A preliminary assessment to determine the impacts of the new accounting standard has been performed. We are currently implementing new accounting and operational processes which will be impacted by the new guidance, but we are unable to provide information on quantitative impacts at this time. We anticipate this standard will have a material impact on individual lines in our consolidated financial statements, but we do not expect it will have as material an impact on our results of operations on an annual basis. The primary impacts of the new standard to our product and service lines are anticipated to be as follows: Brokerage segment Revenue Expense Risk management segment We are currently assessing the timing and measurement of revenue recognition under the new guidance for our risk management segment, specifically third party administration contracts among others, and anticipate that more revenue will be initially deferred and recognized over a longer future period of time than under our current accounting policies. Corporate segment We expect that the timing related to recognition of revenue in our corporate segment will remain substantially unchanged.

Business Combinations

Business Combinations	12 Months Ended
	Dec. 31, 2016
Business Combinations [Abstract]
Business Combinations	3. Business Combinations During 2016, we acquired substantially all of the net assets of the following firms in exchange for our common stock and/or cash. These acquisitions have been accounted for using the acquisition method for recording business combinations (in millions except share data): Name and Effective Date of Acquisition Common Common Cash Accrued Escrow Recorded Total Maximum (000s ) Bomford, Couch & Wilson, Inc. February 1, 2016 — $ — $ 0.9 $ — $ — $ 1.4 $ 2.3 $ 2.1 White & Company Insurance, Inc. February 1, 2016 494 17.4 — — 1.9 — 19.3 — Joseph Distel & Company, Inc. March 1, 2016 — — 1.3 — 0.2 — 1.5 — Vincent L. Braband Insurance, Inc. March 1, 2016 — — 3.0 — 0.3 0.4 3.7 1.1 Kane’s Insurance Management Operations (KIM) March 31, 2016 — — 30.8 — — — 30.8 — Capitol Benefits Group, Inc. April 1, 2016 — — 3.3 — 0.1 0.4 3.8 2.8 Charles Allen Agency, Inc. April 1, 2016 — — 2.8 — 0.2 0.2 3.2 0.7 Hagan Newkirk Financial Services, Inc. April 1, 2016 — — 4.3 — 0.1 0.9 5.3 3.1 Insurance Plans Agency, Inc. April 1, 2016 51 2.3 — — 0.1 0.2 2.6 1.5 KDC Associates, LLC (KDC) April 1, 2016 — — 20.7 — 1.8 3.9 26.4 7.5 Hogan Insurance Services, Inc. May 1, 2016 172 7.4 — — 0.8 1.1 9.3 2.0 (000s) McNeary, Inc. (MNI) May 1, 2016 572 $ 22.0 $ — $ — $ 5.0 $ 0.4 $ 27.4 $ 5.5 Ashmore & Associates Insurance Agency, LLC May 1, 2016 — — 7.7 — 0.4 0.6 8.7 1.7 KRW Insurance Agency, Inc. June 1, 2016 139 5.9 — — 0.7 1.0 7.6 1.6 Buchholz Planning Corporation June 1, 2016 — — 3.9 — 0.1 2.5 6.5 6.0 Blue Horizon Insurance Services, Inc. July 1, 2016 — — 3.4 — 0.4 0.5 4.3 1.0 Brim AB (BRM) July 1, 2016 — — 23.5 6.5 — — 30.0 — Gabor Insurance Services, Inc. July 1, 2016 — — 14.1 — 0.5 — 14.6 — Victory Insurance Agency, Inc. (VIA) July 1, 2016 422 20.9 — 2.3 — 2.6 25.8 4.5 Orb Financial Services Limited August 1, 2016 — — 3.1 — 0.4 2.0 5.5 2.7 Altman & Cronin Benefit Consultants, LLC (ACB) November 1, 2016 — — 31.4 — 2.5 6.6 40.5 19.3 Regency Insurance Group, Inc. (RIG) November 1, 2016 — — 19.2 — 1.0 — 20.2 — Argentis (ARG) November 1, 2016 — — 15.1 0.2 2.2 5.0 22.5 14.5 Group Insurance Associates, Inc. December 1, 2016 — — 9.2 — 0.3 3.0 12.5 6.5 MW Bagnall Company December 1, 2016 — — 5.3 — 0.2 1.1 6.6 5.4 National Ethics Association December 1, 2016 — — 15.6 — 1.7 — 17.3 — Eleven other acquisitions completed in 2016 — — 29.4 0.1 1.3 10.7 41.5 18.0 1,850 $ 75.9 $ 248.0 $ 9.1 $ 22.2 $ 44.5 $ 399.7 $ 107.5 Common shares issued in connection with acquisitions are valued at closing market prices as of the effective date of the applicable acquisition. We record escrow deposits that are returned to us as a result of adjustments to net assets acquired as reductions of goodwill when the escrows are settled. The maximum potential earnout payables disclosed in the foregoing table represent the maximum amount of additional consideration that could be paid pursuant to the terms of the purchase agreement for the applicable acquisition. The amounts recorded as earnout payables, which are primarily based upon the estimated future operating results of the acquired entities over a two- The fair value of these earnout obligations is based on the present value of the expected future payments to be made to the sellers of the acquired entities in accordance with the provisions outlined in the respective purchase agreements, which is a Level 3 fair value measurement. In determining fair value, we estimated the acquired entity’s future performance using financial projections developed by management for the acquired entity and market participant assumptions that were derived for revenue growth and/or profitability. Revenue growth rates generally ranged from 3.5% to 16.0% for our 2016 acquisitions. We estimated future payments using the earnout formula and performance targets specified in each purchase agreement and these financial projections. We then discounted these payments to present value using a risk-adjusted rate that takes into consideration market-based rates of return that reflect the ability of the acquired entity to achieve the targets. These discount rates generally ranged from 8.0% to 9.5% for our 2016 acquisitions. Changes in financial projections, market participant assumptions for revenue growth and/or profitability, or the risk-adjusted discount rate, would result in a change in the fair value of recorded earnout obligations. During 2016, 2015 and 2014, we recognized $16.9 million, $16.2 million and $14.5 million, respectively, of expense in our consolidated statement of earnings related to the accretion of the discount recorded for earnout obligations in connection with our acquisitions. In addition, during 2016, 2015 and 2014, we recognized $15.2 million, $24.4 million and $3.0 million of expense, respectively, related to net adjustments in the estimated fair value of the liability for earnout obligations in connection with revised projections of future performance for 101, 105 and 67 acquisitions, respectively. The aggregate amount of maximum earnout obligations related to acquisitions made in 2013 and subsequent years was $527.2 million as of December 31, 2016, of which $242.3 million was recorded in the consolidated balance sheet as of that date based on the estimated fair value of the expected future payments to be made. The aggregate amount of maximum earnout obligations related to acquisitions made in 2012 and subsequent years was $565.4 million as of December 31, 2015, of which $229.7 million was recorded in the consolidated balance sheet as of that date based on the estimated fair value of the expected future payments to be made. The following is a summary of the estimated fair values of the net assets acquired at the date of each acquisition made in 2016 (in millions): KIM KDC MNI BRM VIA ACB RIG ARG Twenty-nine Total Cash $ 2.2 $ 0.3 $ 3.0 $ 0.5 $ 0.2 $ — $ 0.6 $ 1.4 $ 5.1 $ 13.3 Other current assets 1.8 9.3 1.7 36.0 2.1 1.3 0.6 0.4 14.0 67.2 Fixed assets 0.4 0.1 0.1 0.6 0.1 — — — 2.3 3.6 Noncurrent assets 1.2 — — — — — — 0.3 — 1.5 Goodwill 9.2 12.1 19.5 19.7 18.5 19.9 10.5 12.1 103.9 225.4 Expiration lists 20.0 13.8 13.8 14.6 11.3 18.9 9.3 24.1 92.3 218.1 Non-compete — 0.1 0.1 0.6 0.4 0.4 0.2 — 1.0 2.8 Trade names — — 0.1 0.3 — — — — — 0.4 Total assets acquired 34.8 35.7 38.3 72.3 32.6 40.5 21.2 38.3 218.6 532.3 Current liabilities 3.9 8.9 2.2 33.2 2.2 — 1.0 0.8 14.8 67.0 Noncurrent liabilities 0.1 0.4 8.7 9.1 4.6 — — 15.0 27.7 65.6 Total liabilities assumed 4.0 9.3 10.9 42.3 6.8 — 1.0 15.8 42.5 132.6 Total net assets acquired $ 30.8 $ 26.4 $ 27.4 $ 30.0 $ 25.8 $ 40.5 $ 20.2 $ 22.5 $ 176.1 $ 399.7 Among other things, these acquisitions allow us to expand into desirable geographic locations, further extend our presence in the retail and wholesale insurance brokerage services and risk management industries and increase the volume of general services currently provided. The excess of the purchase price over the estimated fair value of the tangible net assets acquired at the acquisition date was allocated to goodwill, expiration lists, non-compete Provisional estimates of fair value are established at the time of the acquisition and are subsequently reviewed within the first year of operations subsequent to the acquisition date to determine the necessity for adjustments. The fair value of the tangible assets and liabilities for each applicable acquisition at the acquisition date approximated their carrying values. The fair value of expiration lists was established using the excess earnings method, which is an income approach based on estimated financial projections developed by management for each acquired entity using market participant assumptions. Revenue growth and attrition rates generally ranged from 1.0% to 3.0% and 2.5% to 12.5% for our 2016 acquisitions, respectively, for which a valuation was performed. We estimate the fair value as the present value of the benefits anticipated from ownership of the subject customer list in excess of returns required on the investment in contributory assets necessary to realize those benefits. The rate used to discount the net benefits was based on a risk-adjusted rate that takes into consideration market-based rates of return and reflects the risk of the asset relative to the acquired business. These discount rates generally ranged from 12.0% to 19.0% for our 2016 acquisitions, for which a valuation was performed. The fair value of non-compete non-compete Of the $218.1 million of expiration lists, $2.8 million of non-compete Our consolidated financial statements for the year ended December 31, 2016 include the operations of the acquired entities from their respective acquisition dates. The following is a summary of the unaudited pro forma historical results, as if these entities had been acquired at January 1, 2015 (in millions, except per share data): Year Ended December 31, 2016 2015 Total revenues $ 5,663.7 $ 5,528.6 Net earnings attributable to controlling interests 420.6 361.9 Basic earnings per share 2.36 2.08 Diluted earnings per share 2.35 2.07 The unaudited pro forma results above have been prepared for comparative purposes only and do not purport to be indicative of the results of operations which actually would have resulted had these acquisitions occurred at January 1, 2015, nor are they necessarily indicative of future operating results. Annualized revenues of entities acquired in 2016 totaled approximately $137.9 million. Total revenues and net earnings recorded in our consolidated statement of earnings for 2016 related to the 2016 acquisitions in the aggregate were $73.3 million and $4.2 million, respectively.

Other Current Assets

Other Current Assets	12 Months Ended
	Dec. 31, 2016
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Other Current Assets	4. Other Current Assets Major classes of other current assets consist of the following (in millions): December 31, 2016 2015 Premium finance advances and loans $ 241.2 $ 220.2 Accrued supplemental, direct bill and other receivables 177.2 181.1 Refined coal production related receivables 136.9 108.1 Prepaid expenses 78.4 77.8 Total other current assets $ 633.7 $ 587.2 The premium finance loans represent short-term loans which we make to many of our brokerage related clients and other non-brokerage

Fixed Assets

Fixed Assets	12 Months Ended
	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Fixed Assets	5. Fixed Assets Major classes of fixed assets consist of the following (in millions): December 31, 2016 2015 Office equipment $ 22.5 $ 21.1 Furniture and fixtures 96.7 92.7 Leasehold improvements 107.8 106.1 Computer equipment 131.4 143.4 Land and buildings - corporate headquarters 141.7 — Software 268.4 228.3 Other 10.0 10.0 Work in process - includes $30.0 million related to our corporate headquarters in 2015 10.6 46.3 789.1 647.9 Accumulated depreciation (411.5 ) (398.9 ) Net fixed assets $ 377.6 $ 249.0 The amounts in work in process in the table above primarily are for capitalized expenditures incurred related to IT development projects in 2016 and 2015. Also included in work in process in 2015 are capitalized expenditures incurred related to our new corporate headquarters building. In fourth quarter 2016, we reclassified work in process type assets related to our new corporate headquarters and other projects of $46.3 million, included in Other noncurrent assets, to Fixed assets in our consolidated balance sheet as of December 31, 2015.

Intangible Assets

Intangible Assets	12 Months Ended
	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets	6. Intangible Assets The carrying amount of goodwill at December 31, 2016 and 2015 allocated by domestic and foreign operations is as follows (in millions): Brokerage Risk Services Corporate Total At December 31, 2016 United States $ 2,115.0 $ 23.5 $ — $ 2,138.5 United Kingdom 662.2 4.3 — 666.5 Canada 292.2 — — 292.2 Australia 382.7 — — 382.7 New Zealand 205.0 0.3 — 205.3 Other foreign 79.8 — 2.8 82.6 Total goodwill - net $ 3,736.9 $ 28.1 $ 2.8 $ 3,767.8 At December 31, 2015 United States $ 1,946.9 $ 23.5 $ — $ 1,970.4 United Kingdom 779.3 3.5 — 782.8 Canada 282.6 — — 282.6 Australia 380.1 — — 380.1 New Zealand 204.2 0.3 — 204.5 Other foreign 42.5 — — 42.5 Total goodwill - net $ 3,635.6 $ 27.3 $ — $ 3,662.9 The changes in the carrying amount of goodwill for 2016 and 2015 are as follows (in millions): Brokerage Risk Services Corporate Total Balance as of January 1, 2015 $ 3,427.5 $ 22.1 $ — $ 3,449.6 Goodwill acquired during the year 352.6 2.0 — 354.6 Goodwill related to transfers of operations between segments (3.4 ) 3.4 — — Goodwill adjustments related to appraisals and other acquisition adjustments 25.3 — — 25.3 Foreign currency translation adjustments during the year (166.4 ) (0.2 ) — (166.6 ) Balance as of December 31, 2015 3,635.6 27.3 — 3,662.9 Goodwill acquired during the year 222.6 — 2.8 225.4 Goodwill adjustments related to appraisals and other acquisition adjustments 1.8 1.6 — 3.4 Foreign currency translation adjustments during the year (123.1 ) (0.8 ) — (123.9 ) Balance as of December 31, 2016 $ 3,736.9 $ 28.1 $ 2.8 $ 3,767.8 Major classes of amortizable intangible assets consist of the following (in millions): December 31, 2016 2015 Expiration lists $ 2,757.6 $ 2,613.3 Accumulated amortization - expiration lists (1,143.0 ) (934.7 ) 1,614.6 1,678.6 Non-compete 49.3 43.7 Accumulated amortization - non-compete (42.1 ) (34.8 ) 7.2 8.9 Trade names 24.0 25.7 Accumulated amortization - trade names (18.5 ) (14.4 ) 5.5 11.3 Net amortizable assets $ 1,627.3 $ 1,698.8 Estimated aggregate amortization expense for each of the next five years is as follows (in millions): 2017 $ 239.6 2018 226.8 2019 213.1 2020 197.0 2021 174.5 Total $ 1,051.0

Credit and Other Debt Agreement

Credit and Other Debt Agreements	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Credit and Other Debt Agreements	7. Credit and Other Debt Agreements The following is a summary of our corporate and other debt (in millions): 2016 2015 Note Purchase Agreements: Semi-annual payments of interest, fixed rate of 6.44%, balloon due 2017 $ 300.0 $ 300.0 Semi-annual payments of interest, fixed rate of 5.85%, $50 million due in 2018 and 2019 100.0 150.0 Semi-annual payments of interest, fixed rate of 2.80%, balloon due 2018 50.0 50.0 Semi-annual payments of interest, fixed rate of 3.20%, balloon due 2019 50.0 50.0 Semi-annual payments of interest, fixed rate of 3.99%, balloon due 2020 50.0 50.0 Semi-annual payments of interest, fixed rate of 3.48%, balloon due 2020 50.0 50.0 Semi-annual payments of interest, fixed rate of 5.18%, balloon due 2021 75.0 75.0 Semi-annual payments of interest, fixed rate of 3.69%, balloon due 2022 200.0 200.0 Semi-annual payments of interest, fixed rate of 5.49%, balloon due 2023 50.0 50.0 Semi-annual payments of interest, fixed rate of 4.13%, balloon due 2023 200.0 200.0 Semi-annual payments of interest, fixed rate of 4.58%, balloon due 2024 325.0 325.0 Semi-annual payments of interest, fixed rate of 4.31%, balloon due 2025 200.0 200.0 Semi-annual payments of interest, fixed rate of 4.73%, balloon due 2026 175.0 175.0 Semi-annual payments of interest, fixed rate of 4.36%, balloon due 2026 150.0 150.0 Semi-annual payments of interest, fixed rate of 4.40%, balloon due 2026 175.0 — Semi-annual payments of interest, fixed rate of 3.46%, balloon due 2027 100.0 — Semi-annual payments of interest, fixed rate of 4.55%, balloon due 2028 75.0 — Semi-annual payments of interest, fixed rate of 4.98%, balloon due 2029 100.0 100.0 Semi-annual payments of interest, fixed rate of 4.70%, balloon due 2031 25.0 — Total Note Purchase Agreements 2,450.0 2,125.0 Credit Agreement: Periodic payments of interest and principal, prime or LIBOR plus up to 1.45%, was to expires September 19, 2018, replaced with amended and restated facility on April 8, 2016 (see below) 278.0 195.0 Premium Financing Debt Facility - expires May 18, 2017: Periodic payments of interest and principal, Interbank rates plus 1.05% for Facility B; plus 0.55% for Facilities C and D Facility B AUD denominated tranche 100.7 101.2 NZD denominated tranche 9.0 8.5 Facility C and D AUD denominated tranche 5.6 17.2 NZD denominated tranche 10.3 10.1 Total Premium Financing Debt Facility 125.6 137.0 Total corporate and other debt 2,853.6 2,457.0 Less unamortized debt acquisition costs on Note Purchase Agreements (5.4 ) (3.3 ) Net total corporate and other debt $ 2,848.2 $ 2,453.7 Note Purchase Agreements - We are a party to a note purchase agreement dated November 30, 2009, with certain accredited institutional investors, pursuant to which we issued and sold $150.0 million in aggregate principal amount of our 5.85% Senior Notes, Series C, due in three equal installments on November 30, 2016, November 30, 2018 and November 30, 2019, in a private placement. These notes require semi-annual payments of interest that are due in May and November of each year. On November 30, 2016, we funded the $50.0 million 2016 maturity of our Series C note. We are a party to a note purchase agreement dated February 10, 2011, with certain accredited institutional investors, pursuant to which we issued and sold $75.0 million in aggregate principal amount of our 5.18% Senior Notes, Series D, due February 10, 2021 and $50.0 million in aggregate principal amount of our 5.49% Senior Notes, Series E, due February 10, 2023, in a private placement. These notes require semi-annual payments of interest that are due in February and August of each year. We are a party to a note purchase agreement dated July 10, 2012, with certain accredited institutional investors, pursuant to which we issued and sold $50.0 million in aggregate principal amount of our 3.99% Senior Notes, Series F, due July 10, 2020, in a private placement. These notes require semi-annual payments of interest that are due in January and July of each year. We are a party to a note purchase agreement dated June 14, 2013, with certain accredited institutional investors, pursuant to which we issued and sold $200.0 million in aggregate principal amount of our 3.69% Senior Notes, Series G, due June 14, 2022, in a private placement. These notes require semi-annual payments of interest that are due in June and December of each year. We are a party to a note purchase agreement dated December 20, 2013, with certain accredited investors, pursuant to which we issued and sold $325.0 million in aggregate principle amount of our 4.58% Senior Notes, Series H, due February 27, 2024, $175.0 million in aggregate principle amount of our 4.73% Senior Notes, Series I, due February 27, 2026 and $100.0 million in aggregate principle amount of our 4.98% Senior Notes, Series J, due February 27, 2029. These notes will require semi-annual payments of interest that due in February and August of each year. The funding of this note purchase agreement occurred on February 27, 2014. We incurred approximately $1.4 million of debt acquisition costs that was capitalized and will be amortized on a pro rata basis over the life of the debt. We are a party to a note purchase agreement dated June 24, 2014, with certain accredited institutional investors, pursuant to which we issued and sold $50.0 million in aggregate principal amount of our 2.80% Senior Notes, Series K, due June 24, 2018, $50.0 million in aggregate principal amount of our 3.20% Senior Notes, Series L, due June 24, 2019, $50.0 million in aggregate principal amount of our 3.48% Senior Notes, Series M, due June 24, 2020, $200.0 million in aggregate principal amount of our 4.13% Senior Notes, Series N, due June 24, 2023, $200.0 million in aggregate principal amount of our 4.31% Senior Notes, Series O, due June 24, 2025 and $150.0 million in aggregate principal amount of our 4.36% Senior Notes, Series P, due June 24, 2026. These notes require semi-annual payments of interest that are due in June and December of each year. We incurred approximately $2.6 million of debt acquisition costs that was capitalized and will be amortized on a pro rata basis over the life of the debt. We are a party to a note purchase agreement dated June 2, 2016, with certain accredited institutional investors, pursuant to which we issued and sold $175.0 million in aggregate principal amount of our 4.40% Senior Notes, Series Q, due June 2, 2026, $75.0 million in aggregate principal amount of our 4.55% Senior Notes, Series R, due June 2, 2028 and $25.0 million in aggregate principal amount of our 4.70% Senior Notes, Series S, due June 2, 2031. These notes require semi-annual payments of interest that are due in June and December of each year. We incurred approximately $1.2 million of debt acquisition costs that was capitalized and will be amortized on a pro rata basis over the life of the debt. In addition, we realized a cash gain of approximately $1.0 million on the hedging transaction that will be recognized on a pro rata basis as a reduction in our reported interest expense over the ten year life of the debt. We are a party to a note purchase agreement dated December 1, 2016, with certain accredited institutional investors, pursuant to which we issued and sold $100.0 million in aggregate principal amount of our 3.46% Senior Notes, Series T, due December 1, 2027, in a private placement. These notes require semi-annual payments of interest that are due in June and December of each year. Under the terms of the note purchase agreements described above, we may redeem the notes at any time, in whole or in part, at 100% of the principal amount of such notes being redeemed, together with accrued and unpaid interest and a “make-whole amount”. The “make-whole amount” is derived from a net present value computation of the remaining scheduled payments of principal and interest using a discount rate based on the U.S. Treasury yield plus 0.5% and is designed to compensate the purchasers of the notes for their investment risk in the event prevailing interest rates at the time of prepayment are less favorable than the interest rates under the notes. We do not currently intend to prepay any of the notes. The note purchase agreements described above contain customary provisions for transactions of this type, including representations and warranties regarding us and our subsidiaries and various financial covenants, including covenants that require us to maintain specified financial ratios. We were in compliance with these covenants as of December 31, 2016. The note purchase agreements also provide customary events of default, generally with corresponding grace periods, including, without limitation, payment defaults with respect to the notes, covenant defaults, cross-defaults to other agreements evidencing our or our subsidiaries’ indebtedness, certain judgments against us or our subsidiaries and events of bankruptcy involving us or our material subsidiaries. The notes issued under the note purchase agreement are senior unsecured obligations of ours and rank equal in right of payment with our Credit Agreement discussed below. Credit Agreement The Credit Agreement provides that we may elect that each borrowing in U.S. dollars be either base rate loans or eurocurrency loans, each as defined in the Credit Agreement. However, the Credit Agreement provides that all loans denominated in currencies other than U.S. dollars will be eurocurrency loans. Interest rates on base rate loans and outstanding drawings on letters of credit in U.S. dollars under the Credit Agreement will be based on the base rate, as defined in the Credit Agreement, plus a margin of 0.00% to 0.45%, depending on the financial leverage ratio we maintain. Interest rates on eurocurrency loans or outstanding drawings on letters of credit in currencies other than U.S. dollars under the Credit Agreement will be based on adjusted LIBOR, as defined in the Credit Agreement, plus a margin of 0.85% to 1.45%, depending on the financial leverage ratio we maintain. Interest rates on swing loans will be based, at our election, on either the base rate or an alternate rate that may be quoted by the lead lender. The annual facility fee related to the Credit Agreement is 0.15% and 0.30% of the revolving credit commitment, depending on the financial leverage ratio we maintain. In connection with entering into the Credit Agreement, we incurred approximately $2.0 million of debt acquisition costs that were capitalized and will be amortized on a pro rata basis over the term of the Credit Agreement. The terms of the Credit Agreement include various financial covenants, including covenants that require us to maintain specified financial ratios. We were in compliance with these covenants as of December 31, 2016. The Credit Agreement also includes customary provisions for transactions of this type, including events of default, with corresponding grace periods and cross-defaults At December 31, 2016, $21.1 million of letters of credit (for which we had $12.3 million of liabilities recorded at December 31, 2016) were outstanding under the Credit Agreement. See Note 15 to our consolidated financial statements for a discussion of the letters of credit. There were $278.0 million of borrowings outstanding under the Credit Agreement at December 31, 2016. Accordingly, at December 31, 2016, $500.9 million remained available for potential borrowings, of which $53.9 million was available for additional letters of credit. Premium Financing Debt Facility - The interest rates on Facility B are Interbank rates, which vary by tranche, duration and currency, plus a margin of 1.05%. The interest rates on Facilities C and D are 30 day Interbank rates, plus a margin of 0.55%. The annual fee for Facility B is 0.4725% of the undrawn commitments for the two tranches of the facility. The annual fee for Facilities C and D is 0.50% of the total commitments of the facilities. The terms of our Premium Financing Debt Facility include various financial covenants, including covenants that require us to maintain specified financial ratios. We were in compliance with these covenants as of December 31, 2016. The Premium Financing Debt Facility also includes customary provisions for transactions of this type, including events of default, with corresponding grace periods and cross-defaults to other agreements evidencing our indebtedness. Facilities B, C and D are secured by the premium finance receivables of the Australian and New Zealand premium finance subsidiaries. At December 31, 2016, AU$139.0 million and NZ$13.0 million of borrowings were outstanding under Facility B, AU$7.7 million of borrowings were outstanding under Facility C and NZ$14.9 million of borrowings were outstanding under Facility D. Accordingly, as of December 31, 2016, AU$11.0 million and NZ$22.0 million remained available for potential borrowing under Facility B, and AU$17.3 million and NZ$0.1 million under Facilities C and D, respectively. See Note 15 to these consolidated financial statements for additional discussion on our contractual obligations and commitments as of December 31, 2016. The aggregate estimated fair value of the $2,450.0 million in debt under the note purchase agreements at December 31, 2016 was $2,545.0 million due to the long-term duration and fixed interest rates associated with these debt obligations. No active or observable market exists for our private long-term debt. Therefore, the estimated fair value of this debt is based on discounted future cash flows, which is a Level 3 fair value measurement, using current interest rates available for debt with similar terms and remaining maturities. The estimated fair value of this debt is based on the income valuation approach, which is a valuation technique that converts future amounts (for example, cash flows or income and expenses) to a single current (that is, discounted) amount. The fair value measurement is determined on the basis of the value indicated by current market expectations about those future amounts. Because our debt issuances generate a measurable income stream for each lender, the income approach was deemed to be an appropriate methodology for valuing the private placement long-term debt. The methodology used calculated the original deal spread at the time of each debt issuance, which was equal to the difference between the yield of each issuance (the coupon rate) and the equivalent benchmark treasury yield at that time. The market spread as of the valuation date was calculated, which is equal to the difference between an index for investment grade insurers and the equivalent benchmark treasury yield today. An implied premium or discount to the par value of each debt issuance based on the difference between the origination deal spread and market as of the valuation date was then calculated. The index we relied on to represent investment graded insurers was the Bloomberg Valuation Services (BVAL) U.S. Insurers BBB index. This index is comprised primarily of insurance brokerage firms and was representative of the industry in which we operate. For the purposes of our analysis, the average BBB rate was assumed to be the appropriate borrowing rate for us based on our current estimated credit rating. The estimated fair value of the $278.0 million of borrowings outstanding under our Credit Agreement approximate their carrying value due to their short-term duration and variable interest rates. The estimated fair value of the $125.6 million of borrowings outstanding under our Premium Financing Debt Facility approximates their carrying value due to their short-term duration and variable interest rates.

Earnings per Share

Earnings per Share	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Earnings per Share	8. Earnings per Share The following table sets forth the computation of basic and diluted net earnings per share (in millions, except per share data): Year Ended December 31, 2016 2015 2014 Net earnings attributable to controlling interests $ 414.4 $ 356.8 $ 303.4 Weighted average number of common shares outstanding 177.6 172.2 152.9 Dilutive effect of stock options using the treasury stock method 0.8 1.0 1.4 Weighted average number of common and common equivalent shares outstanding 178.4 173.2 154.3 Basic net earnings per share $ 2.33 $ 2.07 $ 1.98 Diluted net earnings per share $ 2.32 $ 2.06 $ 1.97 Options to purchase 5.9 million, 3.5 million and 1.6 million shares of our common stock were outstanding at December 31, 2016, 2015 and 2014, respectively, but were not included in the computation of the dilutive effect of stock options for the year then ended. These stock options were excluded from the computation because the options’ exercise prices were greater than the average market price of our common shares during the respective period and, therefore, would be anti-dilutive to earnings per share under the treasury stock method.

Stock Option Plans

Stock Option Plans	12 Months Ended
	Dec. 31, 2016
Text Block [Abstract]
Stock Option Plans	9. Stock Option Plans On May 13, 2014, our stockholders approved the Arthur J. Gallagher 2014 Long-Term Incentive Plan (which we refer to as the LTIP), which replaced our previous stockholder-approved Arthur J. Gallagher & Co. 2011 Long-Term Incentive Plan (which we refer to as the 2011 LTIP). The LTIP term began May 13, 2014 and terminates on the date of the annual meeting of stockholders in 2021, unless terminated earlier by our board of directors. All of our officers, employees and non-employee non-qualified Shares of our common stock available for issuance under the LTIP include authorized and unissued shares of common stock or authorized and issued shares of common stock reacquired and held as treasury shares or otherwise, or a combination thereof. The number of available shares will be reduced by the aggregate number of shares that become subject to outstanding awards granted under the LTIP. To the extent that shares subject to an outstanding award granted under either the LTIP or the 2011 LTIP are not issued or delivered by reason of the expiration, termination, cancellation or forfeiture of such award or by reason of the settlement of such award in cash, then such shares will again be available for grant under the LTIP. Shares withheld to satisfy tax withholding requirements upon the vesting of awards other than stock options and stock appreciation rights will also be available for grant under the LTIP. Shares that are subject to a stock appreciation right and were not issued upon the net settlement or net exercise of such stock appreciation right, shares that are used to pay the exercise price of an option, delivered to or withheld by us to pay withholding taxes related to stock options or stock appreciation rights, and shares that are purchased on the open market with the proceeds of an option exercise, may not again be made available for issuance. The maximum number of shares available under the LTIP for restricted stock, restricted stock unit awards and performance unit awards settled with stock (i.e., all awards other than stock options and stock appreciation rights) is 1.0 million as of December 31, 2016. To the extent necessary to be qualified performance-based compensation under Section 162(m) of the Internal Revenue Code (which we refer to as the IRC); (i) the maximum number of shares with respect to which options or stock appreciation rights or a combination thereof that may be granted during any fiscal year to any person is 200,000; (ii) the maximum number of shares with respect to which performance-based restricted stock or restricted stock units that may be granted during any fiscal year to any person is 100,000; and (iii) the maximum amount that may be payable with respect to cash-settled performance units granted during any fiscal year to any person is $5.0 million; and (iv) the maximum number of shares with respect to which stock-settled performance units may be granted during any fiscal year to any person is 100,000. The LTIP provides for the grant of stock options, which may be either tax-qualified non-qualified non-qualified tax-qualified non-qualified tax-qualified Upon exercise, the option exercise price may be paid in cash, by the delivery of previously owned shares of our common stock, through a net-exercise non-transferable. On March 17, 2016, the compensation committee granted 2,576,000 options to our officers and key employees that become exercisable at the rate of 34%, 33% and 33% on the anniversary date of the grant in 2019, 2020 and 2021, respectively. On March 11, 2015, the compensation committee granted 1,941,000 options to our officers and key employees that become exercisable at the rate of 34%, 33% and 33% on the anniversary date of the grant in 2018, 2019 and 2020, respectively. On March 12, 2014, the compensation committee granted 1,923,000 options to our officers and key employees that become exercisable at the rate of 34%, 33% and 33% on the anniversary date of the grant in 2017, 2018 and 2019, respectively. The 2016, 2015 and 2014 options expire seven years from the date of grant, or earlier in the event of termination of the employee. For certain of our executive officers age 55 or older, stock options awarded in 2016, 2015, 2014 and 2013 are no longer subject to forfeiture upon such officers’ departure from the company after two years from the date of grant. Our stock option plans provide for the immediate vesting of all outstanding stock option grants in the event of a change in control of our company, as defined in the applicable plan documents. During 2016, 2015 and 2014, we recognized $14.7 million, $11.2 million and $9.5 million, respectively, of compensation expense related to our stock option grants. For purposes of expense recognition in 2016, 2015 and 2014, the estimated fair values of the stock option grants are amortized to expense over the options’ vesting period. We estimated the fair value of stock options at the date of grant using the Black-Scholes option pricing model with the following weighted average assumptions: Year Ended December 31, 2016 2015 2014 Expected dividend yield 3.0 % 3.0 % 3.0 % Expected risk-free interest rate 1.6 % 1.8 % 1.8 % Volatility 27.7 % 28.2 % 28.9 % Expected life (in years) 5.5 5.5 5.5 Option valuation models require the input of highly subjective assumptions including the expected stock price volatility. The Black-Scholes option pricing model was developed for use in estimating the fair value of traded options which have no vesting restrictions and are fully transferable. Because our employee and director stock options have characteristics significantly different from those of traded options, and because changes in the selective input assumptions can materially affect the fair value estimate, in management’s opinion, the existing models do not necessarily provide a reliable single measure of the fair value of our employee and non-employee The following is a summary of our stock option activity and related information for 2016, 2015 and 2014 (in millions, except exercise price and year data): Shares Weighted Weighted (in years) Aggregate Year Ended December 31, 2016 Beginning balance 8.8 $ 39.25 Granted 2.6 43.72 Exercised (1.1 ) 29.50 Forfeited or canceled — — Ending balance 10.3 $ 41.40 4.15 $ 108.8 Exercisable at end of year 2.2 $ 32.37 1.73 $ 43.7 Ending vested and expected to vest 10.1 $ 41.34 4.12 $ 107.5 Year Ended December 31, 2015 Beginning balance 8.4 $ 35.49 Granted 1.9 46.19 Exercised (1.4 ) 27.59 Forfeited or canceled (0.1 ) 27.59 Ending balance 8.8 $ 39.25 4.16 $ 36.7 Exercisable at end of year 2.1 $ 28.54 1.92 $ 25.9 Ending vested and expected to vest 8.7 $ 39.15 4.13 $ 36.6 Year Ended December 31, 2014 Beginning balance 8.3 $ 31.35 Granted 1.9 46.86 Exercised (1.6 ) 28.80 Forfeited or canceled (0.2 ) 28.36 Ending balance 8.4 $ 35.49 3.96 $ 97.2 Exercisable at end of year 2.6 $ 26.91 1.87 $ 52.8 Ending vested and expected to vest 8.3 $ 35.38 3.93 $ 96.6 Options with respect to 4.4 million shares (less any shares of restricted stock issued under the LTIP—see Note 11 to our consolidated financial statements) were available for grant under the LTIP at December 31, 2016. The total intrinsic value of options exercised during 2016, 2015 and 2014 amounted to $19.3 million, $27.0 million and $30.5 million, respectively. At December 31, 2016, we had approximately $41.4 million of total unrecognized compensation cost related to nonvested options. We expect to recognize that cost over a weighted average period of approximately four years. Other information regarding stock options outstanding and exercisable at December 31, 2016 is summarized as follows (in millions, except exercise price and year data): Options Outstanding Options Exercisable Range of Exercise Prices Number Weighted (in years) Weighted Number Weighted $ 23.76 - $ 35.71 2.3 1.52 $ 31.54 1.8 $ 30.65 35.95 - 39.17 1.5 3.20 39.15 0.4 39.12 43.71 - 43.71 2.6 6.21 43.71 — — 46.17 - 49.55 3.9 4.70 46.53 — — $ 23.76 - $ 49.55 10.3 4.15 $ 41.40 2.2 $ 32.37

Deferred Compensation

Deferred Compensation	12 Months Ended
	Dec. 31, 2016
Compensation Related Costs [Abstract]
Deferred Compensation	10. Deferred Compensation We have a Deferred Equity Participation Plan, (which we refer to as the DEPP), which is a non-qualified one-year one-year sub-plans sub-plans) Our common stock that is purchased by the rabbi trust as a contribution under DEPP is valued at historical cost, which equals its fair market value at the date of grant or date of purchase. When common stock is issued, we record an unearned deferred compensation obligation as a reduction of capital in excess of par value in the accompanying consolidated balance sheet, which is amortized to compensation expense ratably over the vesting period of the participants. Future changes in the fair market value of our common stock owed to the participants do not have any impact on the amounts recorded in our consolidated financial statements. In the first quarter of each of 2016, 2015 and 2014, the compensation committee approved $10.1 million, $8.9 million and $9.2 million, respectively, of awards in the aggregate to certain key executives under the DEPP that were contributed to the rabbi trust in the first quarters of 2016, 2015 and 2014. We contributed cash to the rabbi trust and instructed the trustee to acquire a specified number of shares of our common stock on the open market to fund these 2016, 2015 and 2014 awards. In the second quarter of 2013, we instructed the trustee for the DEPP to liquidate all investments held under the DEPP, other than our common stock, and use the proceeds to purchase additional shares of our common stock on the open market. As a result, the DEPP sold all of the funded cash award assets and purchased 1.2 million shares of our common stock at an aggregate cost of $52.4 million during the second quarter of 2013. During 2016, 2015 and 2014, we charged $7.5 million, $7.2 million and $7.4 million, respectively, to compensation expense related to these awards. In 2016, the compensation committee approved $13.6 million of awards under the sub-plans sub-plans At December 31, 2016 and 2015, we recorded $46.8 million (related to 2.4 million shares) and $33.5 million (related to 2.1 million shares), respectively, of unearned deferred compensation as an reduction of capital in excess of par value in the accompanying consolidated balance sheet. The total intrinsic value of our unvested equity based awards under the plan at December 31, 2016 and 2015 was $125.5 million and $85.2 million, respectively. During 2016, 2015 and 2014, cash and equity awards with an aggregate fair value of $7.6 million, $2.3 million and $18.8 million, respectively, were vested and distributed to employees under the DEPP. We have a Deferred Cash Participation Plan (which we refer to as the DCPP), which is a non-qualified

Restricted Stock, Performance S

Restricted Stock, Performance Share and Cash Awards	12 Months Ended
	Dec. 31, 2016
Text Block [Abstract]
Restricted Stock, Performance Share and Cash Awards	11. Restricted Stock, Performance Share and Cash Awards Restricted Stock Awards As discussed in Note 9 to our consolidated financial statements, on May 13, 2014, our stockholders approved the LTIP, which replaced our previous stockholder-approved 2011 LTIP. The LTIP provides for the grant of a stock award either as restricted stock or as restricted stock units. In either case, the compensation committee may determine that the award will be subject to the attainment of performance measures over an established performance period. Stock awards and the related dividend equivalents are non-transferable The agreements awarding restricted stock units under the LTIP will specify whether such awards may be settled in shares of our common stock, cash or a combination of shares and cash and whether the holder will be entitled to receive dividend equivalents, on a current or deferred basis, with respect to such award. Prior to the settlement of a restricted stock unit, the holder of a restricted stock unit will have no rights as a stockholder of the company. The maximum number of shares available under the LTIP for restricted stock, restricted stock units and performance unit awards settled with stock (i.e., all awards other than stock options and stock appreciation rights) is 2.0 million. At December 31, 2016, 1.0 million shares were available for grant under the LTIP for such awards. Prior to May 12, 2009, we had a restricted stock plan for our directors, officers and certain other employees, which was superseded by the 2009 LTIP. Under the provisions of that plan, we were authorized to issue 4.0 million restricted shares or related stock units of our common stock. The compensation committee was responsible for the administration of the plan. Each award granted under the plan represented a right of the holder of the award to receive shares of our common stock, cash or a combination of shares and cash, subject to the holder’s continued employment with us for a period of time after the date the award is granted. The compensation committee determined each recipient of an award under the plan, the number of shares of common stock subject to such award and the period of continued employment required for the vesting of such award. In 2016, 2015 and 2014, we granted 479,167, 394,975 and 376,541 restricted stock units, respectively, to employees under the LTIP, with an aggregate fair value of $20.4 million, $16.7 million and $16.0 million, respectively, at the date of grant. The 2016, 2015 and 2014 restricted stock units vest as follows: 466,600 units granted in first quarter 2016, 362,600 units granted in first quarter 2015 and 323,550 units granted in first quarter 2014, vest in full based on continued employment through March 17, 2021, March 11, 2020 and March 12, 2018, respectively, while the other 2016, 2015 and 2014 restricted stock unit awards generally vest in full based on continued employment through the vesting period on the anniversary date of the grant. In the third quarter of 2014, we granted 33,741 restricted stock units to employees with an aggregate fair value of $1.5 million at the date of grant. These grants vest at the rate of 34%, 33% and 33% on the anniversary date of the grant in 2015, 2016 and 2017, respectively from the date of grant. For certain of our executive officers age 55 or older, restricted stock units awarded in 2016, 2015 and 2014 are no longer subject to forfeiture upon such officers’ departure from the company after two years from the date of grant. The vesting periods of the 2016, 2015 and 2014 restricted stock unit awards are as follows (in actual shares): Restricted Stock Units Granted Vesting Period 2016 2015 2014 One year 27,417 22,175 19,250 Three years — — 33,741 Four years — 9,200 323,550 Five years 451,750 363,600 — Total shares granted 479,167 394,975 376,541 We account for restricted stock unit awards at historical cost, which equals its fair market value at the date of grant, which is amortized to compensation expense ratably over the vesting period of the participants. Future changes in the fair value of our common stock that is owed to the participants do not have any impact on the amounts recorded in our consolidated financial statements. During 2016, 2015 and 2014, we charged $18.2 million, $14.4 million and $12.7 million, respectively, to compensation expense related to restricted stock awards granted in 2007 through 2016. The total intrinsic value of unvested restricted stock at December 31, 2016 and 2015 was $80.0 million and $56.1 million, respectively. During 2016 and 2015, equity awards (including accrued dividends) with an aggregate fair value of $14.2 million and $10.2 million were vested and distributed to employees under this plan. Performance Share Awards On March 17, 2016, March 11, 2015 and March 12, 2014, pursuant to the LTIP, the compensation committee approved 72,900, 53,900 and 48,850, respectively of provisional performance unit awards, with an aggregate fair value of $3.2 million, $2.5 million and $2.3 million, respectively, for future grants to our officers. Each performance unit award was equivalent to the value of one share of our common stock on the date such provisional award was approved. These awards are subject to a one-year two-year one-for-one Cash Awards On March 17, 2016, pursuant to our Performance Unit Program (which we refer to as the Program), the compensation committee approved provisional cash awards of $17.4 million in the aggregate for future grants to our officers and key employees that are denominated in units (397,000 units in the aggregate), each of which was equivalent to the value of one share of our common stock on the date the provisional award was approved. The Program consists of a one-year two-year On March 11, 2015, pursuant to the Program, the compensation committee approved the provisional cash awards of $14.6 million in the aggregate for future grants to our officers and key employees that are denominated in units (315,000 units in the aggregate), each of which was equivalent to the value of one share of our common stock on the date the provisional awards were approved. Terms of the 2015 provisional award were similar to the terms of the 2016 provisional awards. Based on our performance for 2015, we granted 294,000 units under the Program in first quarter 2016 that will fully vest on January 1, 2018. During 2016, we charged $6.6 million to compensation expense related to these awards. We did not recognize any compensation expense during 2015 related to the 2015 awards. On March 12, 2014, pursuant to the Program, the compensation committee approved the provisional cash awards of $10.8 million in the aggregate for future grants to our officers and key employees that are denominated in units (229,000 units in the aggregate), each of which was equivalent to the value of one share of our common stock on the date the provisional awards were approved. Terms of the 2014 provisional award were similar to the terms of the 2015 provisional awards. Based on our performance for 2014, we granted 220,000 units under the Program in first quarter 2015 that will fully vest on January 1, 2017. During 2016 and 2015, we charged $4.5 million and $4.9 million to compensation expense related to these awards. We did not recognize any compensation expense during 2014 related to the 2014 awards. On March 13, 2013, pursuant to the Program, the compensation committee approved the provisional cash awards of $10.5 million in the aggregate for future grants to our officers and key employees that are denominated in units (269,000 units in the aggregate), each of which was equivalent to the value of one share of our common stock on the date the provisional awards were approved. Terms of the 2013 provisional award were similar to the terms of the 2015 provisional awards. Based on our performance for 2013, we granted 263,000 units under the Program in the first quarter of 2014 that will fully vest on January 1, 2016. During 2015 and 2014, we charged $5.3 million and $5.9 million, respectively, to compensation expense related to the 2013 awards. We did not recognize any compensation expense during 2016 related to the 2013 awards. During 2016, cash awards related to the 2013 provisional awards with an aggregate fair value of $11.2 million (246,000 units in the aggregate) were vested and distributed to employees under the Program. During 2015, cash awards related to the 2012 provisional awards with an aggregate fair value of $15.8 million (342,000 units in the aggregate) were vested and distributed to employees under the Program. During 2014, cash awards related to the 2011 provisional awards with an aggregate fair value of $17.6 million (411,000 units in the aggregate) were vested and distributed to employees under the Program.

Retirement Plans

Retirement Plans	12 Months Ended
	Dec. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Retirement Plans	12. Retirement Plans We have a noncontributory defined benefit pension plan that, prior to July 1, 2005, covered substantially all of our domestic employees who had attained a specified age and one year of employment. Benefits under the plan were based on years of service and salary history. In 2005, we amended our defined benefit pension plan to freeze the accrual of future benefits for all U.S. employees, effective on July 1, 2005. Since the plan is frozen, there is no difference between the projected benefit obligation and accumulated benefit obligation at December 31, 2016 and 2015. In the table below, the service cost component represents plan administration costs that are incurred directly by the plan. A reconciliation of the beginning and ending balances of the pension benefit obligation and fair value of plan assets and the funded status of the plan is as follows (in millions): Year Ended December 31, 2016 2015 Change in pension benefit obligation: Benefit obligation at beginning of year $ 261.8 $ 272.0 Service cost 1.5 1.1 Interest cost 10.8 10.8 Net actuarial loss (gain) 1.8 (10.4 ) Benefits paid (14.6 ) (11.7 ) Benefit obligation at end of year $ 261.3 $ 261.8 Change in plan assets: Fair value of plan assets at beginning of year $ 207.5 $ 217.2 Actual return on plan assets 14.9 2.0 Contributions by the company — — Benefits paid (14.6 ) (11.7 ) Fair value of plan assets at end of year $ 207.8 $ 207.5 Funded status of the plan (underfunded) $ (53.5 ) $ (54.3 ) Amounts recognized in the consolidated balance sheet consist of: Noncurrent liabilities - accrued benefit liability $ (53.5 ) $ (54.3 ) Accumulated other comprehensive loss - net actuarial loss 67.9 71.8 Net amount included in retained earnings $ 14.4 $ 17.5 The components of the net periodic pension benefit cost for the plan and other changes in plan assets and obligations recognized in earnings and other comprehensive earnings consist of the following (in millions): Year Ended December 31, 2016 2015 2014 Net periodic pension cost: Service cost $ 1.5 $ 1.1 $ 0.7 Interest cost on benefit obligation 10.8 10.8 12.7 Expected return on plan assets (14.6 ) (15.3 ) (18.7 ) Amortization of net loss 5.3 6.2 2.3 Settlement — — 12.0 Net periodic benefit cost 3.0 2.8 9.0 Other changes in plan assets and obligations recognized in other comprehensive earnings: Net loss incurred 1.4 2.9 42.5 Settlement recognition — — (12.0 ) Amortization of net loss (5.3 ) (6.2 ) (2.3 ) Total recognized in other comprehensive loss (3.9 ) (3.3 ) 28.2 Total recognized in net periodic pension cost and other comprehensive loss $ (0.9 ) $ (0.5 ) $ 37.2 Estimated amortization for the following year: Amortization of net loss $ 5.5 $ 5.9 $ 6.0 The following weighted average assumptions were used at December 31 in determining the plan’s pension benefit obligation: December 31, 2016 2015 Discount rate 4.00 % 4.25 % Weighted average expected long-term rate of return on plan assets 7.25 % 7.25 % The following weighted average assumptions were used at January 1 in determining the plan’s net periodic pension benefit cost: Year Ended December 31, 2016 2015 2014 Discount rate 4.25 % 4.00 % 4.75 % Weighted average expected long-term rate of return on plan assets 7.25 % 7.25 % 7.50 % The following benefit payments are expected to be paid by the plan (in millions): 2017 $ 11.8 2018 12.3 2019 12.9 2020 13.4 2021 14.1 Years 2022 to 2026 77.5 The following is a summary of the plan’s weighted average asset allocations at December 31 by asset category: December 31, Asset Category 2016 2015 Equity securities 61.0 % 59.0 % Debt securities 33.0 % 33.0 % Real estate 6.0 % 8.0 % Total 100.0 % 100.0 % Plan assets are invested in various pooled separate accounts under annuity contracts managed by two life insurance carriers. The plan’s investment policy provides that investments will be allocated in a manner designed to provide a long-term investment return greater than the actuarial assumptions, maximize investment return commensurate with risk and to comply with the Employee Income Retirement Security Act of 1974, as amended (which we refer to as ERISA), by investing the funds in a manner consistent with ERISA’s fiduciary standards. The weighted average expected long-term rate of return on plan assets assumption was determined based on a review of the asset allocation strategy of the plan using expected ten-year ten-year The following is a summary of the plan’s assets carried at fair value as of December 31 by level within the fair value hierarchy (in millions): December 31, Fair Value Hierarchy 2016 2015 Level 1 $ — $ — Level 2 108.1 106.8 Level 3 99.7 100.7 Total fair value $ 207.8 $ 207.5 The plan’s Level 2 assets consist of ownership interests in various pooled separate accounts within a life insurance carrier’s group annuity contract. The fair value of the pooled separate accounts is determined based on the net asset value of the respective funds, which is obtained from the carrier and determined each business day with issuances and redemptions of units of the funds made based on the net asset value per unit as determined on the valuation date. We have not adjusted the net asset values provided by the carrier. There are no restrictions as to the plan’s ability to redeem its investment at the net asset value of the respective funds as of the reporting date. The plan’s Level 3 assets consist of pooled separate accounts within another life insurance carrier’s annuity contracts for which fair value has been determined by an independent valuation. Due to the nature of these annuity contracts, our management makes assumptions to determine how a market participant would price these Level 3 assets. In determining fair value, the future cash flows to be generated by the annuity contracts were estimated using the underlying benefit provisions specified in each contract, market participant assumptions and various actuarial and financial models. These cash flows were then discounted to present value using a risk-adjusted rate that takes into consideration market based rates of return and probability-weighted present values. The following is a reconciliation of the beginning and ending balances for the Level 3 assets of the plan measured at fair value (in millions): Year Ended December 31, 2016 2015 Fair value at January 1 $ 100.7 $ 101.1 Settlements (7.5 ) — Unrealized gains 6.5 (0.4 ) Fair value at December 31 $ 99.7 $ 100.7 We were not required under the Internal Revenue Code (which we refer to as IRC) to make any minimum contributions to the plan for each of the 2016, 2015 and 2014 plan years. This level of required funding is based on the plan being frozen and the aggregate amount of our historical funding. During 2016, 2015 and 2014 we did not make discretionary contributions to the plan. In August 2014, we decided to pursue a pension de-risking lump-sum non-cash We also have a qualified contributory savings and thrift (401(k)) plan covering the majority of our domestic employees. For eligible employees who have met the plan’s age and service requirements to receive matching contributions, we match 100% of pre-tax We also have a nonqualified deferred compensation plan, the Supplemental Savings and Thrift Plan, for certain employees who, due to Internal Revenue Service (which we refer to as the IRS) rules, cannot take full advantage of our matching contributions under the 401(k) plan. The plan permits these employees to annually elect to defer a portion of their compensation until their retirement or a future date. Our matching contributions to this plan (up to a maximum of the lesser of a participant’s elective deferral of base salary, annual bonus and commissions or 5.0% of eligible compensation, less matching amounts contributed under the 401(k) plan) are also at the discretion of our board of directors. We contributed $5.6 million, $4.7 million and $3.7 million to a rabbi trust maintained under the plan in 2016, 2015 and 2014, respectively. The fair value of the assets in the plan’s rabbi trust at December 31, 2016 and 2015, including employee contributions and investment earnings, was $263.3 million and $201.2 million, respectively, and has been included in other noncurrent assets and the corresponding liability has been included in other noncurrent liabilities in the accompanying consolidated balance sheet. We also have several foreign benefit plans, the largest of which is a defined contribution plan that provides for us to make contributions of 5.0% of eligible compensation. In addition, the plan allows for voluntary contributions by U.K. employees, which we match 100%, up to a maximum of an additional 5.0% of eligible compensation. Net expense for foreign retirement plans amounted to $30.6 million, $31.7 million and $29.7 million in 2016, 2015 and 2014, respectively. In 1992, we amended our health benefits plan to eliminate retiree coverage, except for retirees and those employees who had already attained a specified age and length of service at the time of the amendment. The retiree health plan is contributory, with contributions adjusted annually, and is funded on a pay-as-you-go

Investments

Investments	12 Months Ended
	Dec. 31, 2016
Equity Method Investments and Joint Ventures [Abstract]
Investments	13. Investments The following is a summary of our investments and the related funding commitments (in millions): December 31, 2016 December 31, Funding 2015 Assets Commitments Assets Chem-Mod $ 4.0 $ — $ 4.0 Chem-Mod 2.0 — 2.0 C-Quest C-Quest — — — Clean-coal investments: Controlling interest in six limited liability companies that own fourteen 2009 Era Clean Coal Plants 14.3 — 13.9 Non-controlling 0.7 — 0.8 Controlling interest in seventeen limited liability companies that own nineteen 2011 Era Clean Coal Plants 69.0 2.7 60.3 Other investments 3.7 0.7 2.6 Total investments $ 93.7 $ 3.4 $ 83.6 Chem-Mod Chem-Mod. Chem-Mod Chem-Mod’s Chem-Mod™ Chem-Mod™ We believe that the application of The Chem-Mod™ Chem-Mod Chem-Mod Chem-Mod Chem-Mod’s Chem-Mod non-controlling Chem-Mod Chem-Mod Chem-Mod™ C-Quest C-Quest C-Quest) non-controlling C-Quest’s C-Quest C-Quest’s C-Quest C-Quest’s Clean Coal Investments - • We have investments in limited liability companies that own 34 refined coal production plants which produce refined coal using proprietary technologies owned by Chem-Mod. • As of December 31, 2016: • Thirty-one • The remaining three plants are in early stages of seeking and negotiating long-term production contracts. • We have a non-controlling • We and our co-investors on-going on-going Other Investments - non-controlling, low-income low-income

Derivatives and Hedging Activit

Derivatives and Hedging Activity	12 Months Ended
	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives and Hedging Activity	14. Derivatives and Hedging Activity We are exposed to market risks, including changes in foreign currency exchange rates and interest rates. To manage the risk related to these exposures, we enter into various derivative instruments that reduce these risks by creating offsetting exposures. We generally do not enter into derivative transactions for trading or speculative purposes. Foreign Exchange Risk Management We are 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. We use foreign exchange derivatives, typically forward contracts and options, 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. Interest Rate Risk Management We enter into various long term debt agreements. We use interest rate derivatives, typically swaps, to reduce its exposure to the effects of interest rate fluctuations on the forecasted interest rates for up to two years into the future. We has not received or pledged any collateral related to derivative arrangements at December 31, 2016. The notional and fair values of derivative instruments are as follows at December 31, 2016 and 2015 (in millions): Notional Amount Derivatives Assets (1) Derivative Liabilities (2) 2016 2015 2016 2015 2016 2015 Derivatives accounted for as hedges: Interest rate contracts $ 200.0 $ — $ 11.4 $ — $ — $ — Foreign exchange contracts (3) 4.1 93.7 2.1 — 17.5 1.7 Total $ 204.1 $ 93.7 $ 13.5 $ — $ 17.5 $ 1.7 (1) Included within other current assets $12.5 million and zero at December 31, 2016 and 2015, respectively and other non-current (2) Included within other current liabilities $11.8 million and $1.7 million at December 31, 2016 and 2015, respectively and other non-current (3) Included within foreign exchange contracts at December 31, 2016 were $78.3 million of call options offset with $78.3 million of put options and $61.6 million of buy forwards offset with $57.5 million of sell forwards. Included within foreign exchange contracts at December 31, 2015 were $137.6 million of buy forwards, partially offset by $43.9 million of sell forwards. The amounts of derivative gains (losses) recognized in accumulated other comprehensive loss were as follows (in millions): Commission Compensation Operating Interest Revenue Expense Expense Expense Total Year Ended December 31, 2016 Cash flow hedges: Interest rate contracts $ — $ — $ — $ 12.4 $ 12.4 Foreign exchange contracts (24.0 ) 0.1 — — (23.9 ) Total $ (24.0 ) $ 0.1 $ — $ 12.4 $ (11.5 ) Year Ended December 31, 2015 Cash flow hedges: Interest rate contracts $ — $ — $ — $ — $ — Foreign exchange contracts (3.3 ) 0.3 0.2 — (2.8 ) Total $ (3.3 ) $ 0.3 $ 0.2 $ — $ (2.8 ) Year Ended December 31, 2014 Cash flow hedges: Interest rate contracts $ — $ — $ — $ — $ — Foreign exchange contracts (2.5 ) 0.2 0.1 — (2.2 ) Total $ (2.5 ) $ 0.2 $ 0.1 $ — $ (2.2 ) The amounts of derivative gains (losses) reclassified from accumulated other comprehensive loss into income (effective portion) were as follows (in millions): Commission Compensation Operating Interest Revenue Expense Expense Expense Total Year Ended December 31, 2016 Cash flow hedges: Interest rate contracts $ — $ — $ — $ 0.1 $ 0.1 Foreign exchange contracts (9.1 ) 0.5 0.3 — (8.3 ) Total $ (9.1 ) $ 0.5 $ 0.3 $ 0.1 $ (8.2 ) Year Ended December 31, 2015 Cash flow hedges: Interest rate contracts $ — $ — $ — $ — $ — Foreign exchange contracts 0.7 — — — 0.7 Total $ 0.7 $ — $ — $ — $ 0.7 Year Ended December 31, 2014 Cash flow hedges: Interest rate contracts $ — $ — $ — $ — $ — Foreign exchange contracts 0.9 (0.7 ) (0.7 ) — (0.5 ) Total $ 0.9 $ (0.7 ) $ (0.7 ) $ — $ (0.5 ) We estimate that approximately $0.4 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 earnings on the ineffective portion of derivatives for 2016, 2015 and 2014 was $1.6 million, $0.7 million and zero, respectively.

Commitments, Contingencies and

Commitments, Contingencies and Off-Balance Sheet Arrangements	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments, Contingencies and Off-Balance Sheet Arrangements	15. Commitments, Contingencies and Off-Balance In connection with our investing and operating activities, we have entered into certain contractual obligations and commitments. See Notes 7 and 13 to our consolidated financial statements for additional discussion of these obligations and commitments. Our future minimum cash payments, including interest, associated with our contractual obligations pursuant to the note purchase agreements, Credit Agreement, Premium Financing Debt Facility, operating leases and purchase commitments at December 31, 2016 were as follows (in millions): Payments Due by Period Contractual Obligations 2017 2018 2019 2020 2021 Thereafter Total Note purchase agreements $ 300.0 $ 100.0 $ 100.0 $ 100.0 $ 75.0 $ 1,775.0 $ 2,450.0 Credit Agreement 278.0 — — — — — 278.0 Premium Financing Debt Facility 125.6 — — — — — 125.6 Interest on debt 113.5 93.3 89.0 84.4 79.5 280.5 740.2 Total debt obligations 817.1 193.3 189.0 184.4 154.5 2,055.5 3,593.8 Operating lease obligations 101.1 83.8 68.4 56.4 45.8 112.9 468.4 Less sublease arrangements (0.8 ) (0.4 ) (0.1 ) (0.1 ) — (0.1 ) (1.5 ) Outstanding purchase obligations 50.6 32.1 16.6 7.7 1.7 — 108.7 Total contractual obligations $ 968.0 $ 308.8 $ 273.9 $ 248.4 $ 202.0 $ 2,168.3 $ 4,169.4 The amounts presented in the table above may not necessarily reflect our actual future cash funding requirements, because the actual timing of the future payments made may vary from the stated contractual obligation. Outstanding purchase commitments in the table above include $10.6 million related to expenditures on our new corporate headquarters building. Note Purchase Agreements, Credit Agreement and Premium Financing Debt Facility - Operating Lease Obligations - tax-increment We generally operate in leased premises at our other locations. Certain of these leases have options permitting renewals for additional periods. In addition to minimum fixed rentals, a number of leases contain annual escalation clauses which are generally related to increases in an inflation index. Total rent expense, including rent relating to cancelable leases and leases with initial terms of less than one year, amounted to $134.2 million in 2016, $121.6 million in 2015 and $122.0 million in 2014. We have leased certain office space to several non-affiliated Outstanding Purchase Obligations - Off-Balance - Total Amount of Commitment Expiration by Period Amounts Off-Balance 2017 2018 2019 2020 2021 Thereafter Committed Letters of credit $ — $ — $ — $ — $ — $ 21.1 $ 21.1 Financial guarantees 0.2 0.2 0.2 0.2 0.2 1.4 2.4 Funding commitments 2.7 — — — — 0.7 3.4 Total commitments $ 2.9 $ 0.2 $ 0.2 $ 0.2 $ 0.2 $ 23.2 $ 26.9 Since commitments may expire unused, the amounts presented in the table above do not necessarily reflect our actual future cash funding requirements. See Note 13 to our consolidated financial statements for a discussion of our funding commitments related to our corporate segment and the Off-Balance Since January 1, 2002, we have acquired 420 companies, all of which were accounted for using the acquisition method for recording business combinations. Substantially all of the purchase agreements related to these acquisitions contain provisions for potential earnout obligations. For all of our acquisitions made in the period from 2013 to 2016 that contain potential earnout obligations, such obligations are measured at fair value as of the acquisition date and are included on that basis in the recorded purchase price consideration for the respective acquisition. The amounts recorded as earnout payables are primarily based upon estimated future potential operating results of the acquired entities over a two- Off-Balance - At December 31, 2016, we had posted two letters of credit totaling $9.3 million in the aggregate, related to our self-insurance deductibles, for which we had a recorded liability of $12.3 million. We have an equity investment in a rent-a-captive Our commitments associated with outstanding letters of credit, financial guarantees and funding commitments at December 31, 2016 were as follows (all dollar amounts in table are in millions): Compensation Maximum Liability Description, Purpose and Trigger Collateral to Us Exposure Recorded Venture capital funds Funding commitment to one fund - expires in 2023 None None $ 0.7 $ — Other Credit support under letters of credit for deductibles due by us on our own insurance coverages - expires after 2021 None None 9.3 12.3 Credit enhancement under letters of credit for our captive insurance operations to meet minimum statutory capital requirements - expires after 2021 None Reimbursement 6.3 — Credit support under letters of credit for clients’ claim funds held by our Bermuda captive insurance operation in a fiduciary capacity - expires after 2021 None Reimbursement 5.0 — Funding commitments on a clean energy investment - expires when payment is made None None 2.7 — Credit support under letters of credit in lieu of a security deposit for an acquisition’s lease - expires 2023 None None 0.5 — Financial guarantees of loans to 8 Canadian-based employees - expires when loan balances are reduced to zero through May 2029 - Principal and interest payments are paid quarterly (1) None 2.4 — $ 26.9 $ 12.3 (1) The guarantees are collateralized by shares in minority holdings of our Canadian operating companies. Since commitments may expire unused, the amounts presented in the table above do not necessarily reflect our actual future cash funding requirements. Litigation, Regulatory and Taxation Matters - non-compete In July 2014, we were named in a lawsuit which asserts that we and other defendants are liable for infringement of a patent held by Nalco Company. The complaint sought a judgment of infringement, damages, costs and attorneys’ fees, and injunctive relief. Along with the other defendants, we disputed the allegation of infringement and have defended this matter vigorously. We filed a motion to dismiss the complaint on behalf of all defendants, alleging no infringement of Nalco’s intellectual property. This motion and similar motions attacking amended complaints filed by Nalco, were granted. On April 20, 2016, the court dismissed Nalco’s complaint and disallowed any further opportunity to amend or refile. Although Nalco has appealed this ruling, we believe that the probability of a material loss is remote. However, litigation is inherently uncertain and it is not possible for us to predict the ultimate disposition of this proceeding. Our micro-captive advisory services are the subject of an investigation by the Internal Revenue Service (IRS). Additionally, the IRS has initiated audits for the 2012 tax year of over 100 of the micro-captive insurance companies organized and/or managed by us. Among other matters, the IRS is investigating whether we have been acting as a tax shelter promoter in connection with these operations. While the IRS has not made any specific allegations relating to our operations, if the IRS were to successfully assert that the micro-captives organized and/or managed by us do not meet the requirements of IRC Section 831(b), we could be held liable to pay monetary claims by the IRS and/or our micro-captive clients, and our future earnings from our micro-captive operations could be materially adversely affected, any of which events, could negatively impact the overall captive business and adversely affect our consolidated results of operations and financial condition. Due to the fact that the IRS has not made any allegation against us or completed all of its audits of our clients, we are not able to reasonably estimate the amount of any potential loss in connection with this investigation. Contingent Liabilities - Tax-advantaged

Insurance Operations

Insurance Operations	12 Months Ended
	Dec. 31, 2016
Insurance [Abstract]
Insurance Operations	16. Insurance Operations We have ownership interests in several insurance and reinsurance companies based in the U.S., Bermuda, Gibraltar, Guernsey, Isle of Man and Malta that primarily operate segregated account “rent-a-captive” “rent-a-captive” “rent-a-captive” rent-a-captive rent-a-captive We have a wholly owned insurance company subsidiary based in the U.S. that cedes all of its insurance risk to reinsurers or captives under facultative and quota share treaty reinsurance agreements. This company was established in fourth quarter 2014 and began writing business in December 2014. These reinsurance arrangements diversify our business and minimize our exposure to losses or hazards of an unusual nature. The ceding of insurance does not discharge us of our primary liability to the policyholder. In the event that all or any of the reinsuring companies are unable to meet their obligations, we would be liable for such defaulted amounts. Therefore, we are subject to credit risk with respect to the obligations of our reinsurers or captives. In order to minimize our exposure to losses from reinsurer credit risk and insolvencies, we have managed that exposure by obtaining full collateral for which we typically require pledged assets, including cash and/or investment accounts or letters of credit, to fully offset the risk. Reconciliations of direct to net premiums, on a written and earned basis, for 2016, 2015 and 2014 related to the wholly-owned insurance company subsidiary discussed above are as follows (in millions): 2016 2015 2014 Written Earned Written Earned Written Earned Direct $ 71.8 $ 69.6 $ 71.5 $ 71.7 $ 34.9 $ 2.4 Assumed 5.2 4.9 4.4 5.1 2.3 0.2 Ceded (77.0 ) (74.5 ) (75.9 ) (76.8 ) (37.2 ) (2.6 ) Net $ — $ — $ — $ — $ — $ — At December 31, 2016 and 2015, our insurance company subsidiary had reinsurance recoverables of $48.3 million and $40.1 million, respectively, related to liabilities established for ceded unearned premium reserves and loss and loss adjustment expense reserves. These reinsurance recoverables relate to direct and assumed business that has been fully ceded to our reinsurers or captives and have been included in premiums and fees receivables in the accompanying consolidated balance sheet.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	17. Income Taxes We and our principal domestic subsidiaries are included in a consolidated U.S. Federal income tax return. Our international subsidiaries file various income tax returns in their jurisdictions. The foreign earnings (losses) before income taxes were $5.6 million in 2016, $(52.1) million in 2015 and $3.4 million in 2014. Earnings before income taxes include the impact of intercompany interest expense between domestic and foreign legal entities. Foreign intercompany interest expense was $110.7 million in 2016, $107.0 million in 2015 and $76.5 million in 2014. Domestic intercompany interest income was $110.7 million in 2016, $107.0 million in 2015 and $76.5 million in 2014. Significant components of earnings before income taxes and the provision for income taxes are as follows (in millions): Year Ended December 31, 2016 2015 2014 Earnings (losses) before income taxes: United States $ 351.3 $ 345.6 $ 288.1 Foreign, principally Australia, Canada, New Zealand and the U.K. 5.6 (52.1 ) 3.4 Total earnings before income taxes $ 356.9 $ 293.5 $ 291.5 Provision (benefit) for income taxes: Federal: Current $ 45.9 $ 43.9 $ 38.8 Deferred (146.7 ) (139.4 ) (96.6 ) (100.8 ) (95.5 ) (57.8 ) State and local: Current 8.4 18.9 19.5 Deferred (0.3 ) (3.3 ) (1.1 ) 8.1 15.6 18.4 Foreign: Current 22.4 22.9 30.5 Deferred (17.8 ) (38.6 ) (27.1 ) 4.6 (15.7 ) 3.4 Total benefit for income taxes $ (88.1 ) $ (95.6 ) $ (36.0 ) A reconciliation of the provision for income taxes with the U.S. Federal statutory income tax rate is as follows (in millions, except percentages): Year Ended December 31, 2016 2015 2014 Amount % of Amount % of Amount % of Federal statutory rate $ 124.9 35.0 $ 102.7 35.0 $ 102.0 35.0 State income taxes - net of Federal benefit 5.3 1.5 10.2 3.5 12.0 4.1 Differences related to non U.S. operations (34.1 ) (9.6 ) (22.6 ) (7.7 ) (11.2 ) (3.8 ) Alternative energy, foreign and other tax credits (194.4 ) (54.5 ) (181.3 ) (61.8 ) (145.5 ) (49.9 ) Other permanent differences (4.8 ) (1.3 ) (4.9 ) (1.7 ) (2.5 ) (0.9 ) Nondeductible employee compensation — — — — 5.4 1.9 Changes in unrecognized tax benefits 2.2 0.6 3.0 1.0 2.4 0.8 Change in valuation allowance 14.0 3.9 1.7 0.6 — — Change in U.K. tax rate (1.5 ) (0.4 ) (4.2 ) (1.4 ) — — Other 0.3 0.1 (0.2 ) (0.1 ) 1.4 0.5 Benefit for income taxes $ (88.1 ) (24.7 ) $ (95.6 ) (32.6 ) $ (36.0 ) (12.3 ) A reconciliation of the beginning and ending balances of the total amounts of gross unrecognized tax benefits is as follows (in millions): December 31, 2016 2015 Gross unrecognized tax benefits at January 1 $ 15.7 $ 12.5 Increases in tax positions for current year 2.4 2.9 Settlements (1.4 ) — Lapse in statute of limitations (1.8 ) (1.3 ) Increases in tax positions for prior years 1.8 2.1 Decreases in tax positions for prior years (2.2 ) (0.5 ) Gross unrecognized tax benefits at December 31 $ 14.5 $ 15.7 The total amount of net unrecognized tax benefits that, if recognized, would affect the effective tax rate was $10.0 million and $10.8 million at December 31, 2016 and 2015, respectively. We accrue interest and penalties related to unrecognized tax benefits in our provision for income taxes. At December 31, 2016 and 2015, we had accrued interest and penalties related to unrecognized tax benefits of $2.8 million and $1.1 million, respectively. We file income tax returns in the U.S. and in various state, local and foreign jurisdictions. We are routinely examined by tax authorities in these jurisdictions. At December 31, 2016, our corporate returns had been examined by the IRS through calendar year 2010. The IRS is currently conducting various examinations of calendar years 2011 and 2012. In addition, a number of foreign, state, local and partnership examinations are currently ongoing. It is reasonably possible that our gross unrecognized tax benefits may change within the next twelve months. However, we believe any changes in the recorded balance would not have a significant impact on our consolidated financial statements. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of our deferred tax assets and liabilities are as follows (in millions): December 31, 2016 2015 Deferred tax assets: Alternative minimum tax and other credit carryforwards $ 477.9 $ 341.6 Accrued and unfunded compensation and employee benefits 219.0 197.0 Amortizable intangible assets 38.8 39.4 Compensation expense related to stock options 16.9 12.6 Accrued liabilities 31.7 34.3 Accrued pension liability 22.9 23.4 Investments 7.7 9.5 Net operating loss carryforwards 20.4 19.2 Capital loss carryforwards 16.0 2.9 Deferred rent liability 8.1 8.7 Other 3.9 7.7 Total deferred tax assets 863.3 696.3 Valuation allowance for deferred tax assets (66.8 ) (52.8 ) Deferred tax assets 796.5 643.5 Deferred tax liabilities: Nondeductible amortizable intangible assets 310.2 307.1 Investment-related partnerships 34.5 28.7 Depreciable fixed assets 18.2 11.7 Hedging instruments 4.1 — Other prepaid items 4.1 4.6 Total deferred tax liabilities 371.1 352.1 Net deferred tax assets $ 425.4 $ 291.4 At December 31, 2016 and 2015, $371.1 million and $352.1 million, respectively, have been included in noncurrent liabilities in the accompanying consolidated balance sheet. Alternative minimum tax credits of $108.2 million have an indefinite life, general business tax credits of $368.8 million begin to expire, if not utilized, in 2033, and state credits of $0.9 million expire, if not used, in 2021. We expect the historically favorable trend in earnings before income taxes to continue in the foreseeable future. Accordingly, we expect to make full use of the net deferred tax assets. Valuation allowances have been established for certain foreign intangible assets and various state net operating loss carryforwards that may not be utilized in the future. We do not provide for U.S. Federal income taxes on the undistributed earnings ($243.0 million and $231.9 million at December 31, 2016 and 2015, respectively) of foreign subsidiaries which are considered permanently invested outside of the U.S. The amount of unrecognized deferred tax liability on these undistributed earnings was $15.6 million and $10.4 million at December 31, 2016 and 2015, respectively.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Earnings	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Accumulated Other Comprehensive Earnings	18. Accumulated Other Comprehensive Earnings The after-tax Pension Foreign Fair Value Accumulated Balance as of January 1, 2014 $ (25.6 ) $ 22.1 $ 0.9 $ (2.6 ) Net change in period (18.6 ) (238.4 ) (1.0 ) (258.0 ) Balance as of December 31, 2014 (44.2 ) (216.3 ) (0.1 ) (260.6 ) Net change in period 1.3 (261.1 ) (2.1 ) (261.9 ) Balance as of December 31, 2015 (42.9 ) (477.4 ) (2.2 ) (522.5 ) Net change in period (4.4 ) (231.8 ) (4.9 ) (241.1 ) Balance as of December 31, 2016 $ (47.3 ) $ (709.2 ) $ (7.1 ) $ (763.6 ) The foreign currency translation in 2016, 2015 and 2014 primarily relates to the net impact of changes in the value of the local currencies relative to the U.S. dollar for our operations in Australia, Canada, the Caribbean, India, New Zealand and the U.K. During 2016, 2015 and 2014, $5.3 million, $6.2 million and $14.3 million, respectively, of expense related to the pension liability was reclassified from accumulated other comprehensive loss to compensation expense in the statement of earnings. During 2016, 2015 and 2014, $8.2 million of expense, $0.7 million of income and $0.5 million of expense, respectively, related to the fair value of derivative investments was reclassified from accumulated other comprehensive loss to the statement of earnings. During 2016, 2015 and 2014, no amounts related to foreign currency translation were reclassified from accumulated other comprehensive loss to the statement of earnings.

Quarterly Operating Results (un

Quarterly Operating Results (unaudited)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Quarterly Operating Results (unaudited)	19. Quarterly Operating Results (unaudited) Quarterly operating results for 2016 and 2015 were as follows (in millions, except per share data): 1st 2nd 3rd 4th 2016 Total revenues $ 1,300.4 $ 1,427.1 $ 1,482.3 $ 1,385.0 Total expenses 1,244.7 1,289.6 1,387.4 1,316.2 Earnings before income taxes $ 55.7 $ 137.5 $ 94.9 $ 68.8 Net earnings attributable to controlling interests $ 46.5 $ 150.0 $ 122.8 $ 95.1 Basic net earnings per share $ 0.26 $ 0.85 $ 0.69 $ 0.53 Diluted net earnings per share $ 0.26 $ 0.84 $ 0.69 $ 0.53 2015 Total revenues $ 1,231.3 $ 1,371.4 $ 1,454.8 $ 1,334.9 Total expenses 1,200.4 1,242.9 1,349.1 1,306.5 Earnings before income taxes $ 30.9 $ 128.5 $ 105.7 $ 28.4 Net earnings attributable to controlling interests $ 21.9 $ 139.3 $ 133.3 $ 62.3 Basic net earnings per share $ 0.13 $ 0.82 $ 0.76 $ 0.35 Diluted net earnings per share $ 0.13 $ 0.81 $ 0.75 $ 0.35

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2016
Segment Reporting [Abstract]
Segment Information	20. Segment Information We have three reportable operating segments: brokerage, risk management and corporate. The brokerage segment is primarily comprised of our retail and wholesale insurance brokerage operations. The brokerage segment generates revenues through commissions paid by insurance underwriters and through fees charged to our clients. Our brokers, agents and administrators act as intermediaries between insurers and their customers and we do not assume net underwriting risks. The risk management segment provides contract claim settlement and administration services for enterprises that choose to self-insure some or all of their property/casualty coverages and for insurance companies that choose to outsource some or all of their property/casualty claims departments. These operations also provide claims management, loss control consulting and insurance property appraisal services. Revenues are principally generated on a negotiated per-claim per-service Financial information relating to our segments for 2016, 2015 and 2014 is as follows (in millions): Year Ended December 31, 2016 Brokerage Risk Management Corporate Total Revenues: Commissions $ 2,439.1 $ — $ — $ 2,439.1 Fees 775.7 717.1 — 1,492.8 Supplemental commissions 147.0 — — 147.0 Contingent commissions 107.2 — — 107.2 Investment income 52.3 1.0 — 53.3 Gains on books of business sales and other 6.6 — — 6.6 Revenue from clean coal activities — — 1,350.1 1,350.1 Other - net gain — — (1.3 ) (1.3 ) Total revenues 3,527.9 718.1 1,348.8 5,594.8 Compensation 2,041.8 424.5 72.6 2,538.9 Operating 600.9 171.4 25.4 797.7 Cost of revenues from clean coal activities — — 1,408.6 1,408.6 Interest — — 109.8 109.8 Depreciation 57.2 27.2 19.2 103.6 Amortization 244.7 2.5 — 247.2 Change in estimated acquisition earnout payables 32.1 — — 32.1 Total expenses 2,976.7 625.6 1,635.6 5,237.9 Earnings (loss) before income taxes 551.2 92.5 (286.8 ) 356.9 Provision (benefit) for income taxes 194.1 35.3 (317.5 ) (88.1 ) Net earnings 357.1 57.2 30.7 445.0 Net earnings attributable to noncontrolling interests 3.6 — 27.0 30.6 Net earnings attributable to controlling interests $ 353.5 $ 57.2 $ 3.7 $ 414.4 Net foreign exchange gain $ 2.9 $ — $ 0.1 $ 3.0 Revenues: United States $ 2,334.4 $ 610.3 $ 1,327.9 $ 4,272.6 United Kingdom 686.5 25.6 — 712.1 Australia 172.5 73.0 — 245.5 Canada 134.1 4.1 — 138.2 New Zealand 120.7 5.1 — 125.8 Other foreign 79.7 — 20.9 100.6 Total revenues $ 3,527.9 $ 718.1 $ 1,348.8 $ 5,594.8 At December 31, 2016 Identifiable assets: United States $ 4,393.6 $ 540.5 $ 1,622.2 $ 6,556.3 United Kingdom 2,321.9 61.8 — 2,383.7 Australia 894.4 56.9 — 951.3 Canada 573.3 2.8 — 576.1 New Zealand 668.9 4.4 — 673.3 Other foreign 331.3 — 17.6 348.9 Total identifiable assets $ 9,183.4 $ 666.4 $ 1,639.8 $ 11,489.6 Goodwill - net $ 3,736.9 $ 28.1 $ 2.8 $ 3,767.8 Amortizable intangible assets - net 1,613.6 13.7 — 1,627.3 Year Ended December 31, 2015 Brokerage Risk Management Corporate Total Revenues: Commissions $ 2,338.7 $ — $ — $ 2,338.7 Fees 705.8 726.5 — 1,432.3 Supplemental commissions 125.5 — — 125.5 Contingent commissions 93.7 — — 93.7 Investment income 53.6 0.6 — 54.2 Gains on books of business sales and other 6.7 — — 6.7 Revenue from clean coal activities — — 1,310.8 1,310.8 Other - net gain — — 30.5 30.5 Total revenues 3,324.0 727.1 1,341.3 5,392.4 Compensation 1,939.7 427.2 62.0 2,428.9 Operating 638.1 180.8 21.8 840.7 Cost of revenues from clean coal activities — — 1,351.5 1,351.5 Interest — — 103.0 103.0 Depreciation 54.4 24.3 15.2 93.9 Amortization 237.3 3.0 — 240.3 Change in estimated acquisition earnout payables 41.1 (0.5 ) — 40.6 Total expenses 2,910.6 634.8 1,553.5 5,098.9 Earnings (loss) before income taxes 413.4 92.3 (212.2 ) 293.5 Provision (benefit) for income taxes 145.3 35.1 (276.0 ) (95.6 ) Net earnings 268.1 57.2 63.8 389.1 Net earnings attributable to noncontrolling interests 1.7 — 30.6 32.3 Net earnings attributable to controlling interests $ 266.4 $ 57.2 $ 33.2 $ 356.8 Net foreign exchange gain (loss) $ (0.2 ) $ — $ 0.4 $ 0.2 Revenues: United States $ 2,122.1 $ 591.8 $ 1,327.5 $ 4,041.4 United Kingdom 738.5 28.4 — 766.9 Australia 157.3 99.4 — 256.7 Canada 133.1 3.5 — 136.6 New Zealand 118.6 4.0 — 122.6 Other foreign 54.4 — 13.8 68.2 Total revenues $ 3,324.0 $ 727.1 $ 1,341.3 $ 5,392.4 At December 31, 2015 Identifiable assets: United States $ 4,092.8 $ 525.2 $ 1,264.9 $ 5,882.9 United Kingdom 2,580.0 72.1 — 2,652.1 Australia 895.8 55.6 — 951.4 Canada 575.0 3.1 — 578.1 New Zealand 623.1 4.1 — 627.2 Other foreign 203.0 — 19.1 222.1 Total identifiable assets $ 8,969.7 $ 660.1 $ 1,284.0 $ 10,913.8 Goodwill - net $ 3,635.6 $ 27.3 $ — $ 3,662.9 Amortizable intangible assets - net 1,677.8 21.0 — 1,698.8 Year Ended December 31, 2014 Brokerage Risk Corporate Total Revenues: Commissions $ 2,083.0 $ — $ — $ 2,083.0 Fees 577.0 681.3 — 1,258.3 Supplemental commissions 104.0 — — 104.0 Contingent commissions 84.7 — — 84.7 Investment income 40.3 1.0 — 41.3 Gains on books of business sales and other 7.3 — — 7.3 Revenue from clean coal activities — — 1,029.5 1,029.5 Other - net gain — — 18.4 18.4 Total revenues 2,896.3 682.3 1,047.9 4,626.5 Compensation 1,703.1 414.2 50.3 2,167.6 Operating 530.1 176.4 36.6 743.1 Cost of revenues from clean coal activities — — 1,058.9 1,058.9 Interest — — 89.0 89.0 Depreciation 44.4 21.2 3.8 69.4 Amortization 186.3 3.2 — 189.5 Change in estimated acquisition earnout payables 17.6 (0.1 ) — 17.5 Total expenses 2,481.5 614.9 1,238.6 4,335.0 Earnings (loss) before income taxes 414.8 67.4 (190.7 ) 291.5 Provision (benefit) for income taxes 151.0 25.3 (212.3 ) (36.0 ) Net earnings 263.8 42.1 21.6 327.5 Net earnings attributable to noncontrolling interests 0.9 — 23.2 24.1 Net earnings (loss) attributable to controlling interests $ 262.9 $ 42.1 $ (1.6 ) $ 303.4 Net foreign exchange gain (loss) $ 1.1 $ — $ (0.6 ) $ 0.5 Revenues: United States $ 1,873.3 $ 532.6 $ 1,036.9 $ 3,442.8 United Kingdom 696.8 29.4 — 726.2 Australia 122.4 114.2 — 236.6 Canada 81.8 3.2 — 85.0 New Zealand 78.4 2.9 — 81.3 Other foreign 43.6 — 11.0 54.6 Total revenues $ 2,896.3 $ 682.3 $ 1,047.9 $ 4,626.5 At December 31, 2014 Identifiable assets: United States $ 3,557.1 $ 457.5 $ 1,032.0 $ 5,046.6 United Kingdom 2,376.4 74.0 — 2,450.4 Australia 992.2 39.0 — 1,031.2 Canada 639.2 2.8 — 642.0 New Zealand 614.1 1.6 — 615.7 Other foreign 207.2 — 16.9 224.1 Total identifiable assets $ 8,386.2 $ 574.9 $ 1,048.9 $ 10,010.0 Goodwill - net $ 3,427.5 $ 22.1 $ — $ 3,449.6 Amortizable intangible assets - net 1,757.3 18.7 — 1,776.0

Schedule II. Valuation and Qual

Schedule II. Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2016
Valuation and Qualifying Accounts [Abstract]
Schedule II. Valuation and Qualifying Accounts	Schedule II Arthur J. Gallagher & Co. Valuation and Qualifying Accounts Balance Amounts Adjustments Balance (In millions) Year ended December 31, 2016 Allowance for doubtful accounts $ 13.3 $ 4.9 $ (5.4 )(1) $ 12.8 Allowance for estimated policy cancellations 7.4 0.2 (0.5 )(2) 7.1 Accumulated amortization of expiration lists, noncompete agreements and trade names 983.9 247.2 (27.5 )(3) 1,203.6 Year ended December 31, 2015 Allowance for doubtful accounts $ 10.7 $ 5.7 $ (3.1 )(1) $ 13.3 Allowance for estimated policy cancellations 6.8 3.6 (3.0 )(2) 7.4 Accumulated amortization of expiration lists, noncompete agreements and trade names 758.8 240.3 (15.2 )(3) 983.9 Year ended December 31, 2014 Allowance for doubtful accounts $ 6.7 $ 2.7 $ 1.3 (1) $ 10.7 Allowance for estimated policy cancellations 4.2 (0.2 ) 2.8 (2) 6.8 Accumulated amortization of expiration lists, noncompete agreements and trade names 544.1 189.5 25.2 (3) 758.8 (1) Net activity of bad debt write offs and recoveries and acquired businesses. (2) Additions to allowance related to acquired businesses. (3) Elimination of fully amortized expiration lists, non-compete

Summary of Significant Accoun30

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Nature of Operations	Nature of Operations -
Basis of Presentation	Basis of Presentation - In the preparation of our consolidated financial statements as of December 31, 2016, management evaluated all material subsequent events or transactions that occurred after the balance sheet date through the date on which the financial statements were issued for potential recognition in our consolidated financial statements and/or disclosure in the notes thereto.
Use of Estimates	Use of Estimates
Revenue Recognition	Revenue Recognition We recognize commission revenues at the later of the billing or the effective date of the related insurance policies, net of an allowance for estimated policy cancellations. We recognize commission revenues related to installment premiums as the installments are billed. We recognize supplemental commission revenues using internal data and information received from insurance carriers that allows us to reasonably estimate the supplemental commissions earned in the period. A supplemental commission is a commission paid by an insurance carrier that is above the base commission paid, is determined by the insurance carrier, and is established annually in advance of the contractual period based on historical performance criteria. We recognize contingent commissions and commissions on premiums directly billed by insurance carriers as revenue when we have obtained the data necessary to reasonably determine such amounts. Typically, we cannot reasonably determine these types of commission revenues until we have received the cash or the related policy detail or other carrier specific information from the insurance carrier. A contingent commission is a commission paid by an insurance carrier based on the overall profit and/or volume of the business placed with that insurance carrier during a particular calendar year and is determined after the contractual period. Commissions on premiums billed directly by insurance carriers to the insureds generally relate to a large number of property/casualty insurance policy transactions, each with small premiums, and comprise a substantial portion of the revenues generated by our employee benefit brokerage operations. Under these direct bill arrangements, the insurance carrier controls the entire billing and policy issuance process. We record the income effects of subsequent premium adjustments when the adjustments become known. Fee revenues generated from the brokerage segment primarily relate to fees negotiated in lieu of commissions that we recognize in the same manner as commission revenues. Fee revenues generated from the risk management segment relate to third party claims administration, loss control and other risk management consulting services, which we provide over a period of time, typically one year. We recognize these fee revenues ratably as the services are rendered, and record the income effects of subsequent fee adjustments when the adjustments become known. We deduct brokerage expense from gross revenues in our determination of our total revenues. Brokerage expense represents commissions paid to sub-brokers Premiums and fees receivable in the accompanying consolidated balance sheet are net of allowances for estimated policy cancellations and doubtful accounts. The allowance for estimated policy cancellations was $7.1 million and $7.4 million at December 31, 2016 and 2015, respectively, which represents a reserve for future reversals in commission and fee revenues related to the potential cancellation of client insurance policies that were in force as of each year end. The allowance for doubtful accounts was $12.8 million and $13.3 million at December 31, 2016 and 2015, respectively. We establish the allowance for estimated policy cancellations through a charge to revenues and the allowance for doubtful accounts through a charge to operating expenses. Both of these allowances are based on estimates and assumptions using historical data to project future experience. Such estimates and assumptions could change in the future as more information becomes known which could impact the amounts reported and disclosed herein. We periodically review the adequacy of these allowances and make adjustments as necessary. Investment income primarily includes interest and dividend income (including interest income from our premium financing operations), which is accrued as it is earned. Gains on books of business sales represent one-time
Claims Handling Obligations	Claims Handling Obligations run-off
Earnings per Share	Earnings per Share
Cash and Cash Equivalents	Cash and Cash Equivalents
Restricted Cash	Restricted Cash Related to our third party administration business and in certain of our brokerage operations, we are responsible for client claim funds that we hold in a fiduciary capacity. We do not earn any interest income on the funds held. These client funds have been included in restricted cash, along with a corresponding liability in premiums payable to insurance and reinsurance companies in the accompanying consolidated balance sheet.
Derivative Instruments	Derivative Instruments
Premium Financing	Premium Financing
Fixed Assets	Fixed Assets Useful Life Office equipment Three to ten years Furniture and fixtures Three to ten years Computer equipment Three to five years Building Fifteen to forty years Software Three to five years Refined fuel plants Ten years Leasehold improvements Shorter of the lease term or useful life of the asset
Intangible Assets	Intangible Assets non-compete non-compete non-compete non-compete We review all of our intangible assets for impairment periodically (at least annually for goodwill) and whenever events or changes in business circumstances indicate that the carrying value of the assets may not be recoverable. We perform such impairment reviews at the division (i.e., reporting unit) level with respect to goodwill and at the business unit level for amortizable intangible assets. In reviewing intangible assets, if the fair value were less than the carrying amount of the respective (or underlying) asset, an indicator of impairment would exist and further analysis would be required to determine whether or not a loss would need to be charged against current period earnings as a component of amortization expense. Based on the results of impairment reviews in 2016, 2015 and 2014, we wrote off $1.8 million, $11.5 million and $1.8 million, respectively, of amortizable intangible assets primarily related to prior year acquisitions of our brokerage segment, which is included in amortization expense in the accompanying consolidated statement of earnings. The determinations of impairment indicators and fair value are based on estimates and assumptions related to the amount and timing of future cash flows and future interest rates. Such estimates and assumptions could change in the future as more information becomes known which could impact the amounts reported and disclosed herein.
Income Taxes	Income Taxes two-step Uncertain tax positions are measured based upon the facts and circumstances that exist at each reporting period and involve significant management judgment. Subsequent changes in judgment based upon new information may lead to changes in recognition, derecognition and measurement. Adjustments may result, for example, upon resolution of an issue with the taxing authorities, or expiration of a statute of limitations barring an assessment for an issue. We recognize interest and penalties, if any, related to unrecognized tax benefits in our provision for income taxes. Tax law requires certain items to be included in our tax returns at different times than such items are reflected in the financial statements. As a result, the annual tax expense reflected in our consolidated statements of earnings is different than that reported in our tax returns. Some of these differences are permanent, such as expenses that are not deductible in our tax returns, and some differences are temporary and reverse over time, such as depreciation expense and amortization expense deductible for income tax purposes. Temporary differences create deferred tax assets and liabilities. Deferred tax liabilities generally represent tax expense recognized in the financial statements for which a tax payment has been deferred, or expense which has been deducted in the tax return but has not yet been recognized in the financial statements. Deferred tax assets generally represent items that can be used as a tax deduction or credit in tax returns in future years for which a benefit has already been recorded in the financial statements. We establish or adjust valuation allowances for deferred tax assets when we estimate that it is more likely than not that future taxable income will be insufficient to fully use a deduction or credit in a specific jurisdiction. In assessing the need for the recognition of a valuation allowance for deferred tax assets, we consider whether it is more likely than not that some portion, or all, of the deferred tax assets will not be realized and adjust the valuation allowance accordingly. We evaluate all significant available positive and negative evidence as part of our analysis. Negative evidence includes the existence of losses in recent years. Positive evidence includes the forecast of future taxable income by jurisdiction, tax-planning
Fair Value of Financial Instruments	Fair Value of Financial Instruments The classification of a financial instrument within the valuation hierarchy is based upon the transparency of inputs to the valuation of an asset or liability on the measurement date. The three levels of the hierarchy in order of priority of inputs to the valuation technique are defined as follows: • Level 1 - Valuations are based on unadjusted quoted prices in active markets for identical financial instruments; • Level 2 - Valuations are based on quoted market prices, other than quoted prices included in Level 1, in markets that are not active or on inputs that are observable either directly or indirectly for the full term of the financial instrument; and • Level 3 - Valuations are based on pricing or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement of the financial instrument. Such inputs may reflect management’s own assumptions about the assumptions a market participant would use in pricing the financial instrument. The level in the fair value hierarchy within which the fair value measurement is classified is determined based on the lowest level input that is significant to the fair value measure in its entirety. The carrying amounts of financial assets and liabilities reported in the accompanying consolidated balance sheet for cash and cash equivalents, restricted cash, premiums and fees receivable, premiums payable to insurance carriers, accrued salaries and bonuses, accounts payable and other accrued liabilities, unearned fees and income taxes payable, at December 31, 2016 and 2015, approximate fair value because of the short-term duration of these instruments. See Note 3 to our consolidated financial statements for the fair values related to the establishment of intangible assets and the establishment and adjustment of earnout payables. See Note 7 to our consolidated financial statements for the fair values related to borrowings outstanding at December 31, 2016 and 2015 under our debt agreements. See Note 12 to our consolidated financial statements for the fair values related to investments at December 31, 2016 and 2015 under our defined benefit pension plan.
Litigation	Litigation -
Retention Bonus Arrangements	Retention bonus arrangements
Stock-Based Compensation	Stock-Based Compensation - paid-in Cash-settled share-based payments to employees include awards under our Performance Unit Program and stock appreciation rights. The fair value of the amount payable to employees in respect of cash-settled share-based payments is recognized as compensation expense, with a corresponding increase in liabilities, over the vesting period. The liability is remeasured at each reporting date and at settlement date. Any changes in fair value of the liability are recognized as compensation expense. We recognize share-based compensation expense over the requisite service period for awards expected to ultimately vest. Forfeitures are estimated on the date of grant and revised if actual or expected forfeiture activity differs from original estimates.
Employee Stock Purchase Plan	Employee Stock Purchase Plan
Defined Benefit Pension and Other Postretirement Plans	Defined Benefit Pension and Other Postretirement Plans
Leases	Leases In February 2016, the Financial Accounting Standards Board (which we refer to as the FASB) issued Accounting Standards Update (which we refer to as ASU) 2016-02, right-of-use We anticipate this guidance will have a material impact on our consolidated financial statements. While we are continuing to assess all potential impacts of the new guidance, we currently believe the most significant impact relates to our real estate operating leases and the related recognition of right-of-use
Cash Receipts and Cash Payments	Cash Receipts and Cash Payments In August 2016, the FASB issued ASU No. 2016-15, (ASU 2016-15). ASU 2016-15
Consolidations	Consolidations In October 2016, the FASB issued ASU No. 2016-17, 2015-02, In February 2015, the FASB issued ASU No. 2015-02, Amendments to the Consolidation Analysis. This new accounting guidance on consolidations eliminates the deferral granted to investment companies from applying the variable interest entities guidance and makes targeted amendments to the current consolidation guidance. The new guidance applies to all entities involved with limited partnerships or similar entities and will require re-evaluation of these entities under the revised guidance, which could have changed previous consolidation conclusions. The new guidance was effective in first quarter 2016 and has been applied by us. The adoption of this guidance did not have a material impact on our consolidated financial statements.
Debt Issuance Costs	Debt Issuance Costs In April 2015, the FASB issued ASU No. 2015-03, non-current -
Intangibles - Goodwill and Other	Intangibles - Goodwill and Other In April 2015, the FASB issued ASU No. 2015-05, Other—Internal-Use (Subtopic 350-40): internal-use
Business Combinations	Business Combinations In September 2015, the FASB issued ASU No. 2015-16,
Segment Reporting	Brokerage segment Revenue Expense Risk management segment We are currently assessing the timing and measurement of revenue recognition under the new guidance for our risk management segment, specifically third party administration contracts among others, and anticipate that more revenue will be initially deferred and recognized over a longer future period of time than under our current accounting policies. Corporate segment We expect that the timing related to recognition of revenue in our corporate segment will remain substantially unchanged.

Summary of Significant Accoun31

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Summary of Estimated Useful Life of Fixed Assets	Depreciation for fixed assets is computed using the straight-line method over the following estimated useful lives: Useful Life Office equipment Three to ten years Furniture and fixtures Three to ten years Computer equipment Three to five years Building Fifteen to forty years Software Three to five years Refined fuel plants Ten years Leasehold improvements Shorter of the lease term or useful life of the asset

Business Combinations (Tables)

Business Combinations (Tables)	12 Months Ended
	Dec. 31, 2016
Business Combinations [Abstract]
Acquisition Method for Recording Business Combinations	During 2016, we acquired substantially all of the net assets of the following firms in exchange for our common stock and/or cash. These acquisitions have been accounted for using the acquisition method for recording business combinations (in millions except share data): Name and Effective Date of Acquisition Common Common Cash Accrued Escrow Recorded Total Maximum (000s ) Bomford, Couch & Wilson, Inc. February 1, 2016 — $ — $ 0.9 $ — $ — $ 1.4 $ 2.3 $ 2.1 White & Company Insurance, Inc. February 1, 2016 494 17.4 — — 1.9 — 19.3 — Joseph Distel & Company, Inc. March 1, 2016 — — 1.3 — 0.2 — 1.5 — Vincent L. Braband Insurance, Inc. March 1, 2016 — — 3.0 — 0.3 0.4 3.7 1.1 Kane’s Insurance Management Operations (KIM) March 31, 2016 — — 30.8 — — — 30.8 — Capitol Benefits Group, Inc. April 1, 2016 — — 3.3 — 0.1 0.4 3.8 2.8 Charles Allen Agency, Inc. April 1, 2016 — — 2.8 — 0.2 0.2 3.2 0.7 Hagan Newkirk Financial Services, Inc. April 1, 2016 — — 4.3 — 0.1 0.9 5.3 3.1 Insurance Plans Agency, Inc. April 1, 2016 51 2.3 — — 0.1 0.2 2.6 1.5 KDC Associates, LLC (KDC) April 1, 2016 — — 20.7 — 1.8 3.9 26.4 7.5 Hogan Insurance Services, Inc. May 1, 2016 172 7.4 — — 0.8 1.1 9.3 2.0 (000s) McNeary, Inc. (MNI) May 1, 2016 572 $ 22.0 $ — $ — $ 5.0 $ 0.4 $ 27.4 $ 5.5 Ashmore & Associates Insurance Agency, LLC May 1, 2016 — — 7.7 — 0.4 0.6 8.7 1.7 KRW Insurance Agency, Inc. June 1, 2016 139 5.9 — — 0.7 1.0 7.6 1.6 Buchholz Planning Corporation June 1, 2016 — — 3.9 — 0.1 2.5 6.5 6.0 Blue Horizon Insurance Services, Inc. July 1, 2016 — — 3.4 — 0.4 0.5 4.3 1.0 Brim AB (BRM) July 1, 2016 — — 23.5 6.5 — — 30.0 — Gabor Insurance Services, Inc. July 1, 2016 — — 14.1 — 0.5 — 14.6 — Victory Insurance Agency, Inc. (VIA) July 1, 2016 422 20.9 — 2.3 — 2.6 25.8 4.5 Orb Financial Services Limited August 1, 2016 — — 3.1 — 0.4 2.0 5.5 2.7 Altman & Cronin Benefit Consultants, LLC (ACB) November 1, 2016 — — 31.4 — 2.5 6.6 40.5 19.3 Regency Insurance Group, Inc. (RIG) November 1, 2016 — — 19.2 — 1.0 — 20.2 — Argentis (ARG) November 1, 2016 — — 15.1 0.2 2.2 5.0 22.5 14.5 Group Insurance Associates, Inc. December 1, 2016 — — 9.2 — 0.3 3.0 12.5 6.5 MW Bagnall Company December 1, 2016 — — 5.3 — 0.2 1.1 6.6 5.4 National Ethics Association December 1, 2016 — — 15.6 — 1.7 — 17.3 — Eleven other acquisitions completed in 2016 — — 29.4 0.1 1.3 10.7 41.5 18.0 1,850 $ 75.9 $ 248.0 $ 9.1 $ 22.2 $ 44.5 $ 399.7 $ 107.5
Summary of Estimated Fair Values of Net Assets Acquired	The following is a summary of the estimated fair values of the net assets acquired at the date of each acquisition made in 2016 (in millions): KIM KDC MNI BRM VIA ACB RIG ARG Twenty-nine Total Cash $ 2.2 $ 0.3 $ 3.0 $ 0.5 $ 0.2 $ — $ 0.6 $ 1.4 $ 5.1 $ 13.3 Other current assets 1.8 9.3 1.7 36.0 2.1 1.3 0.6 0.4 14.0 67.2 Fixed assets 0.4 0.1 0.1 0.6 0.1 — — — 2.3 3.6 Noncurrent assets 1.2 — — — — — — 0.3 — 1.5 Goodwill 9.2 12.1 19.5 19.7 18.5 19.9 10.5 12.1 103.9 225.4 Expiration lists 20.0 13.8 13.8 14.6 11.3 18.9 9.3 24.1 92.3 218.1 Non-compete — 0.1 0.1 0.6 0.4 0.4 0.2 — 1.0 2.8 Trade names — — 0.1 0.3 — — — — — 0.4 Total assets acquired 34.8 35.7 38.3 72.3 32.6 40.5 21.2 38.3 218.6 532.3 Current liabilities 3.9 8.9 2.2 33.2 2.2 — 1.0 0.8 14.8 67.0 Noncurrent liabilities 0.1 0.4 8.7 9.1 4.6 — — 15.0 27.7 65.6 Total liabilities assumed 4.0 9.3 10.9 42.3 6.8 — 1.0 15.8 42.5 132.6 Total net assets acquired $ 30.8 $ 26.4 $ 27.4 $ 30.0 $ 25.8 $ 40.5 $ 20.2 $ 22.5 $ 176.1 $ 399.7
Summary of Unaudited Pro Forma Historical Results	The following is a summary of the unaudited pro forma historical results, as if these entities had been acquired at January 1, 2015 (in millions, except per share data): Year Ended December 31, 2016 2015 Total revenues $ 5,663.7 $ 5,528.6 Net earnings attributable to controlling interests 420.6 361.9 Basic earnings per share 2.36 2.08 Diluted earnings per share 2.35 2.07

Other Current Assets (Tables)

Other Current Assets (Tables)	12 Months Ended
	Dec. 31, 2016
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Summary of Major Classes of Other Current Assets	Major classes of other current assets consist of the following (in millions): December 31, 2016 2015 Premium finance advances and loans $ 241.2 $ 220.2 Accrued supplemental, direct bill and other receivables 177.2 181.1 Refined coal production related receivables 136.9 108.1 Prepaid expenses 78.4 77.8 Total other current assets $ 633.7 $ 587.2

Fixed Assets (Tables)

Fixed Assets (Tables)	12 Months Ended
	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Summary of Fixed Assets	Major classes of fixed assets consist of the following (in millions): December 31, 2016 2015 Office equipment $ 22.5 $ 21.1 Furniture and fixtures 96.7 92.7 Leasehold improvements 107.8 106.1 Computer equipment 131.4 143.4 Land and buildings - corporate headquarters 141.7 — Software 268.4 228.3 Other 10.0 10.0 Work in process - includes $30.0 million related to our corporate headquarters in 2015 10.6 46.3 789.1 647.9 Accumulated depreciation (411.5 ) (398.9 ) Net fixed assets $ 377.6 $ 249.0

Intangible Assets (Tables)

Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Carrying Amount of Goodwill Allocated by Domestic and Foreign Operations	The carrying amount of goodwill at December 31, 2016 and 2015 allocated by domestic and foreign operations is as follows (in millions): Brokerage Risk Services Corporate Total At December 31, 2016 United States $ 2,115.0 $ 23.5 $ — $ 2,138.5 United Kingdom 662.2 4.3 — 666.5 Canada 292.2 — — 292.2 Australia 382.7 — — 382.7 New Zealand 205.0 0.3 — 205.3 Other foreign 79.8 — 2.8 82.6 Total goodwill - net $ 3,736.9 $ 28.1 $ 2.8 $ 3,767.8 At December 31, 2015 United States $ 1,946.9 $ 23.5 $ — $ 1,970.4 United Kingdom 779.3 3.5 — 782.8 Canada 282.6 — — 282.6 Australia 380.1 — — 380.1 New Zealand 204.2 0.3 — 204.5 Other foreign 42.5 — — 42.5 Total goodwill - net $ 3,635.6 $ 27.3 $ — $ 3,662.9
Changes in Carrying Amount of Goodwill	The changes in the carrying amount of goodwill for 2016 and 2015 are as follows (in millions): Brokerage Risk Services Corporate Total Balance as of January 1, 2015 $ 3,427.5 $ 22.1 $ — $ 3,449.6 Goodwill acquired during the year 352.6 2.0 — 354.6 Goodwill related to transfers of operations between segments (3.4 ) 3.4 — — Goodwill adjustments related to appraisals and other acquisition adjustments 25.3 — — 25.3 Foreign currency translation adjustments during the year (166.4 ) (0.2 ) — (166.6 ) Balance as of December 31, 2015 3,635.6 27.3 — 3,662.9 Goodwill acquired during the year 222.6 — 2.8 225.4 Goodwill adjustments related to appraisals and other acquisition adjustments 1.8 1.6 — 3.4 Foreign currency translation adjustments during the year (123.1 ) (0.8 ) — (123.9 ) Balance as of December 31, 2016 $ 3,736.9 $ 28.1 $ 2.8 $ 3,767.8
Major Classes of Amortizable Intangible Assets	Major classes of amortizable intangible assets consist of the following (in millions): December 31, 2016 2015 Expiration lists $ 2,757.6 $ 2,613.3 Accumulated amortization - expiration lists (1,143.0 ) (934.7 ) 1,614.6 1,678.6 Non-compete 49.3 43.7 Accumulated amortization - non-compete (42.1 ) (34.8 ) 7.2 8.9 Trade names 24.0 25.7 Accumulated amortization - trade names (18.5 ) (14.4 ) 5.5 11.3 Net amortizable assets $ 1,627.3 $ 1,698.8
Estimated Aggregate Amortization Expense	Estimated aggregate amortization expense for each of the next five years is as follows (in millions): 2017 $ 239.6 2018 226.8 2019 213.1 2020 197.0 2021 174.5 Total $ 1,051.0

Credit and Other Debt Agreeme36

Credit and Other Debt Agreements (Tables)	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Summary of Corporate and Other Debt	The following is a summary of our corporate and other debt (in millions): 2016 2015 Note Purchase Agreements: Semi-annual payments of interest, fixed rate of 6.44%, balloon due 2017 $ 300.0 $ 300.0 Semi-annual payments of interest, fixed rate of 5.85%, $50 million due in 2018 and 2019 100.0 150.0 Semi-annual payments of interest, fixed rate of 2.80%, balloon due 2018 50.0 50.0 Semi-annual payments of interest, fixed rate of 3.20%, balloon due 2019 50.0 50.0 Semi-annual payments of interest, fixed rate of 3.99%, balloon due 2020 50.0 50.0 Semi-annual payments of interest, fixed rate of 3.48%, balloon due 2020 50.0 50.0 Semi-annual payments of interest, fixed rate of 5.18%, balloon due 2021 75.0 75.0 Semi-annual payments of interest, fixed rate of 3.69%, balloon due 2022 200.0 200.0 Semi-annual payments of interest, fixed rate of 5.49%, balloon due 2023 50.0 50.0 Semi-annual payments of interest, fixed rate of 4.13%, balloon due 2023 200.0 200.0 Semi-annual payments of interest, fixed rate of 4.58%, balloon due 2024 325.0 325.0 Semi-annual payments of interest, fixed rate of 4.31%, balloon due 2025 200.0 200.0 Semi-annual payments of interest, fixed rate of 4.73%, balloon due 2026 175.0 175.0 Semi-annual payments of interest, fixed rate of 4.36%, balloon due 2026 150.0 150.0 Semi-annual payments of interest, fixed rate of 4.40%, balloon due 2026 175.0 — Semi-annual payments of interest, fixed rate of 3.46%, balloon due 2027 100.0 — Semi-annual payments of interest, fixed rate of 4.55%, balloon due 2028 75.0 — Semi-annual payments of interest, fixed rate of 4.98%, balloon due 2029 100.0 100.0 Semi-annual payments of interest, fixed rate of 4.70%, balloon due 2031 25.0 — Total Note Purchase Agreements 2,450.0 2,125.0 Credit Agreement: Periodic payments of interest and principal, prime or LIBOR plus up to 1.45%, was to expires September 19, 2018, replaced with amended and restated facility on April 8, 2016 (see below) 278.0 195.0 Premium Financing Debt Facility - expires May 18, 2017: Periodic payments of interest and principal, Interbank rates plus 1.05% for Facility B; plus 0.55% for Facilities C and D Facility B AUD denominated tranche 100.7 101.2 NZD denominated tranche 9.0 8.5 Facility C and D AUD denominated tranche 5.6 17.2 NZD denominated tranche 10.3 10.1 Total Premium Financing Debt Facility 125.6 137.0 Total corporate and other debt 2,853.6 2,457.0 Less unamortized debt acquisition costs on Note Purchase Agreements (5.4 ) (3.3 ) Net total corporate and other debt $ 2,848.2 $ 2,453.7

Earnings per Share (Tables)

Earnings per Share (Tables)	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net EPS	The following table sets forth the computation of basic and diluted net earnings per share (in millions, except per share data): Year Ended December 31, 2016 2015 2014 Net earnings attributable to controlling interests $ 414.4 $ 356.8 $ 303.4 Weighted average number of common shares outstanding 177.6 172.2 152.9 Dilutive effect of stock options using the treasury stock method 0.8 1.0 1.4 Weighted average number of common and common equivalent shares outstanding 178.4 173.2 154.3 Basic net earnings per share $ 2.33 $ 2.07 $ 1.98 Diluted net earnings per share $ 2.32 $ 2.06 $ 1.97

Stock Option Plans (Tables)

Stock Option Plans (Tables)	12 Months Ended
	Dec. 31, 2016
Text Block [Abstract]
Black-Scholes Option Pricing Model with Weighted Average	For purposes of expense recognition in 2016, 2015 and 2014, the estimated fair values of the stock option grants are amortized to expense over the options’ vesting period. We estimated the fair value of stock options at the date of grant using the Black-Scholes option pricing model with the following weighted average assumptions: Year Ended December 31, 2016 2015 2014 Expected dividend yield 3.0 % 3.0 % 3.0 % Expected risk-free interest rate 1.6 % 1.8 % 1.8 % Volatility 27.7 % 28.2 % 28.9 % Expected life (in years) 5.5 5.5 5.5
Stock Option Activity and Related Information	The following is a summary of our stock option activity and related information for 2016, 2015 and 2014 (in millions, except exercise price and year data): Shares Weighted Weighted (in years) Aggregate Year Ended December 31, 2016 Beginning balance 8.8 $ 39.25 Granted 2.6 43.72 Exercised (1.1 ) 29.50 Forfeited or canceled — — Ending balance 10.3 $ 41.40 4.15 $ 108.8 Exercisable at end of year 2.2 $ 32.37 1.73 $ 43.7 Ending vested and expected to vest 10.1 $ 41.34 4.12 $ 107.5 Year Ended December 31, 2015 Beginning balance 8.4 $ 35.49 Granted 1.9 46.19 Exercised (1.4 ) 27.59 Forfeited or canceled (0.1 ) 27.59 Ending balance 8.8 $ 39.25 4.16 $ 36.7 Exercisable at end of year 2.1 $ 28.54 1.92 $ 25.9 Ending vested and expected to vest 8.7 $ 39.15 4.13 $ 36.6 Year Ended December 31, 2014 Beginning balance 8.3 $ 31.35 Granted 1.9 46.86 Exercised (1.6 ) 28.80 Forfeited or canceled (0.2 ) 28.36 Ending balance 8.4 $ 35.49 3.96 $ 97.2 Exercisable at end of year 2.6 $ 26.91 1.87 $ 52.8 Ending vested and expected to vest 8.3 $ 35.38 3.93 $ 96.6
Other Information Regarding Stock Options Outstanding and Exercisable	Other information regarding stock options outstanding and exercisable at December 31, 2016 is summarized as follows (in millions, except exercise price and year data): Options Outstanding Options Exercisable Range of Exercise Prices Number Weighted (in years) Weighted Number Weighted $ 23.76 - $ 35.71 2.3 1.52 $ 31.54 1.8 $ 30.65 35.95 - 39.17 1.5 3.20 39.15 0.4 39.12 43.71 - 43.71 2.6 6.21 43.71 — — 46.17 - 49.55 3.9 4.70 46.53 — — $ 23.76 - $ 49.55 10.3 4.15 $ 41.40 2.2 $ 32.37

Restricted Stock, Performance39

Restricted Stock, Performance Share and Cash Awards (Tables)	12 Months Ended
	Dec. 31, 2016
Text Block [Abstract]
Schedule of Restricted Stock Awards Vesting Periods	The vesting periods of the 2016, 2015 and 2014 restricted stock unit awards are as follows (in actual shares): Restricted Stock Units Granted Vesting Period 2016 2015 2014 One year 27,417 22,175 19,250 Three years — — 33,741 Four years — 9,200 323,550 Five years 451,750 363,600 — Total shares granted 479,167 394,975 376,541

Retirement Plans (Tables)

Retirement Plans (Tables)	12 Months Ended
	Dec. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Reconciliation of Balances of Pension Benefit Obligation and Fair Value of Plan Assets	A reconciliation of the beginning and ending balances of the pension benefit obligation and fair value of plan assets and the funded status of the plan is as follows (in millions): Year Ended December 31, 2016 2015 Change in pension benefit obligation: Benefit obligation at beginning of year $ 261.8 $ 272.0 Service cost 1.5 1.1 Interest cost 10.8 10.8 Net actuarial loss (gain) 1.8 (10.4 ) Benefits paid (14.6 ) (11.7 ) Benefit obligation at end of year $ 261.3 $ 261.8 Change in plan assets: Fair value of plan assets at beginning of year $ 207.5 $ 217.2 Actual return on plan assets 14.9 2.0 Contributions by the company — — Benefits paid (14.6 ) (11.7 ) Fair value of plan assets at end of year $ 207.8 $ 207.5 Funded status of the plan (underfunded) $ (53.5 ) $ (54.3 ) Amounts recognized in the consolidated balance sheet consist of: Noncurrent liabilities - accrued benefit liability $ (53.5 ) $ (54.3 ) Accumulated other comprehensive loss - net actuarial loss 67.9 71.8 Net amount included in retained earnings $ 14.4 $ 17.5
Components of Net Periodic Pension Benefit Cost and Other Changes in Plan Assets and Obligations Recognized in Earnings and Other Comprehensive Earnings	The components of the net periodic pension benefit cost for the plan and other changes in plan assets and obligations recognized in earnings and other comprehensive earnings consist of the following (in millions): Year Ended December 31, 2016 2015 2014 Net periodic pension cost: Service cost $ 1.5 $ 1.1 $ 0.7 Interest cost on benefit obligation 10.8 10.8 12.7 Expected return on plan assets (14.6 ) (15.3 ) (18.7 ) Amortization of net loss 5.3 6.2 2.3 Settlement — — 12.0 Net periodic benefit cost 3.0 2.8 9.0 Other changes in plan assets and obligations recognized in other comprehensive earnings: Net loss incurred 1.4 2.9 42.5 Settlement recognition — — (12.0 ) Amortization of net loss (5.3 ) (6.2 ) (2.3 ) Total recognized in other comprehensive loss (3.9 ) (3.3 ) 28.2 Total recognized in net periodic pension cost and other comprehensive loss $ (0.9 ) $ (0.5 ) $ 37.2 Estimated amortization for the following year: Amortization of net loss $ 5.5 $ 5.9 $ 6.0
Weighted Average Assumptions of Pension Benefit Obligation and Net Periodic Pension Benefit Cost	The following weighted average assumptions were used at December 31 in determining the plan’s pension benefit obligation: December 31, 2016 2015 Discount rate 4.00 % 4.25 % Weighted average expected long-term rate of return on plan assets 7.25 % 7.25 % The following weighted average assumptions were used at January 1 in determining the plan’s net periodic pension benefit cost: Year Ended December 31, 2016 2015 2014 Discount rate 4.25 % 4.00 % 4.75 % Weighted average expected long-term rate of return on plan assets 7.25 % 7.25 % 7.50 %
Schedule of Benefit Payments Expected to be Paid by Plan	The following benefit payments are expected to be paid by the plan (in millions): 2017 $ 11.8 2018 12.3 2019 12.9 2020 13.4 2021 14.1 Years 2022 to 2026 77.5
Summary of Plans Weighted Average Asset Allocations	The following is a summary of the plan’s weighted average asset allocations at December 31 by asset category: December 31, Asset Category 2016 2015 Equity securities 61.0 % 59.0 % Debt securities 33.0 % 33.0 % Real estate 6.0 % 8.0 % Total 100.0 % 100.0 %
Summary of Plan's Assets Carried at Fair Value	The following is a summary of the plan’s assets carried at fair value as of December 31 by level within the fair value hierarchy (in millions): December 31, Fair Value Hierarchy 2016 2015 Level 1 $ — $ — Level 2 108.1 106.8 Level 3 99.7 100.7 Total fair value $ 207.8 $ 207.5
Reconciliation of Beginning and Ending Balances for Level 3 Assets of Plan Measured at Fair Value	The following is a reconciliation of the beginning and ending balances for the Level 3 assets of the plan measured at fair value (in millions): Year Ended December 31, 2016 2015 Fair value at January 1 $ 100.7 $ 101.1 Settlements (7.5 ) — Unrealized gains 6.5 (0.4 ) Fair value at December 31 $ 99.7 $ 100.7

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2016
Equity Method Investments and Joint Ventures [Abstract]
Investments Reported in Other Current and Non-Current Assets	The following is a summary of our investments and the related funding commitments (in millions): December 31, 2016 December 31, Funding 2015 Assets Commitments Assets Chem-Mod $ 4.0 $ — $ 4.0 Chem-Mod 2.0 — 2.0 C-Quest C-Quest — — — Clean-coal investments: Controlling interest in six limited liability companies that own fourteen 2009 Era Clean Coal Plants 14.3 — 13.9 Non-controlling 0.7 — 0.8 Controlling interest in seventeen limited liability companies that own nineteen 2011 Era Clean Coal Plants 69.0 2.7 60.3 Other investments 3.7 0.7 2.6 Total investments $ 93.7 $ 3.4 $ 83.6

Derivatives and Hedging Activ42

Derivatives and Hedging Activity (Tables)	12 Months Ended
	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of Notional and Fair Values of Derivative Instruments	The notional and fair values of derivative instruments are as follows at December 31, 2016 and 2015 (in millions): Notional Amount Derivatives Assets (1) Derivative Liabilities (2) 2016 2015 2016 2015 2016 2015 Derivatives accounted for as hedges: Interest rate contracts $ 200.0 $ — $ 11.4 $ — $ — $ — Foreign exchange contracts (3) 4.1 93.7 2.1 — 17.5 1.7 Total $ 204.1 $ 93.7 $ 13.5 $ — $ 17.5 $ 1.7 (1) Included within other current assets $12.5 million and zero at December 31, 2016 and 2015, respectively and other non-current (2) Included within other current liabilities $11.8 million and $1.7 million at December 31, 2016 and 2015, respectively and other non-current (3) Included within foreign exchange contracts at December 31, 2016 were $78.3 million of call options offset with $78.3 million of put options and $61.6 million of buy forwards offset with $57.5 million of sell forwards. Included within foreign exchange contracts at December 31, 2015 were $137.6 million of buy forwards, partially offset by $43.9 million of sell forwards.
Summary of Amounts of Derivative Gains (Losses) Recognized In Accumulated Other Comprehensive Loss	The amounts of derivative gains (losses) recognized in accumulated other comprehensive loss were as follows (in millions): Commission Compensation Operating Interest Revenue Expense Expense Expense Total Year Ended December 31, 2016 Cash flow hedges: Interest rate contracts $ — $ — $ — $ 12.4 $ 12.4 Foreign exchange contracts (24.0 ) 0.1 — — (23.9 ) Total $ (24.0 ) $ 0.1 $ — $ 12.4 $ (11.5 ) Year Ended December 31, 2015 Cash flow hedges: Interest rate contracts $ — $ — $ — $ — $ — Foreign exchange contracts (3.3 ) 0.3 0.2 — (2.8 ) Total $ (3.3 ) $ 0.3 $ 0.2 $ — $ (2.8 ) Year Ended December 31, 2014 Cash flow hedges: Interest rate contracts $ — $ — $ — $ — $ — Foreign exchange contracts (2.5 ) 0.2 0.1 — (2.2 ) Total $ (2.5 ) $ 0.2 $ 0.1 $ — $ (2.2 ) The amounts of derivative gains (losses) reclassified from accumulated other comprehensive loss into income (effective portion) were as follows (in millions): Commission Compensation Operating Interest Revenue Expense Expense Expense Total Year Ended December 31, 2016 Cash flow hedges: Interest rate contracts $ — $ — $ — $ 0.1 $ 0.1 Foreign exchange contracts (9.1 ) 0.5 0.3 — (8.3 ) Total $ (9.1 ) $ 0.5 $ 0.3 $ 0.1 $ (8.2 ) Year Ended December 31, 2015 Cash flow hedges: Interest rate contracts $ — $ — $ — $ — $ — Foreign exchange contracts 0.7 — — — 0.7 Total $ 0.7 $ — $ — $ — $ 0.7 Year Ended December 31, 2014 Cash flow hedges: Interest rate contracts $ — $ — $ — $ — $ — Foreign exchange contracts 0.9 (0.7 ) (0.7 ) — (0.5 ) Total $ 0.9 $ (0.7 ) $ (0.7 ) $ — $ (0.5 )

Commitments, Contingencies an43

Commitments, Contingencies and Off-Balance Sheet Arrangements (Tables)	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Contractual Obligations	Our future minimum cash payments, including interest, associated with our contractual obligations pursuant to the note purchase agreements, Credit Agreement, Premium Financing Debt Facility, operating leases and purchase commitments at December 31, 2016 were as follows (in millions): Payments Due by Period Contractual Obligations 2017 2018 2019 2020 2021 Thereafter Total Note purchase agreements $ 300.0 $ 100.0 $ 100.0 $ 100.0 $ 75.0 $ 1,775.0 $ 2,450.0 Credit Agreement 278.0 — — — — — 278.0 Premium Financing Debt Facility 125.6 — — — — — 125.6 Interest on debt 113.5 93.3 89.0 84.4 79.5 280.5 740.2 Total debt obligations 817.1 193.3 189.0 184.4 154.5 2,055.5 3,593.8 Operating lease obligations 101.1 83.8 68.4 56.4 45.8 112.9 468.4 Less sublease arrangements (0.8 ) (0.4 ) (0.1 ) (0.1 ) — (0.1 ) (1.5 ) Outstanding purchase obligations 50.6 32.1 16.6 7.7 1.7 — 108.7 Total contractual obligations $ 968.0 $ 308.8 $ 273.9 $ 248.4 $ 202.0 $ 2,168.3 $ 4,169.4
Off-Balance Sheet Commitments	Off-Balance - Total Amount of Commitment Expiration by Period Amounts Off-Balance 2017 2018 2019 2020 2021 Thereafter Committed Letters of credit $ — $ — $ — $ — $ — $ 21.1 $ 21.1 Financial guarantees 0.2 0.2 0.2 0.2 0.2 1.4 2.4 Funding commitments 2.7 — — — — 0.7 3.4 Total commitments $ 2.9 $ 0.2 $ 0.2 $ 0.2 $ 0.2 $ 23.2 $ 26.9
Outstanding Letters of Credit and Funding Commitments	Our commitments associated with outstanding letters of credit, financial guarantees and funding commitments at December 31, 2016 were as follows (all dollar amounts in table are in millions): Compensation Maximum Liability Description, Purpose and Trigger Collateral to Us Exposure Recorded Venture capital funds Funding commitment to one fund - expires in 2023 None None $ 0.7 $ — Other Credit support under letters of credit for deductibles due by us on our own insurance coverages - expires after 2021 None None 9.3 12.3 Credit enhancement under letters of credit for our captive insurance operations to meet minimum statutory capital requirements - expires after 2021 None Reimbursement 6.3 — Credit support under letters of credit for clients’ claim funds held by our Bermuda captive insurance operation in a fiduciary capacity - expires after 2021 None Reimbursement 5.0 — Funding commitments on a clean energy investment - expires when payment is made None None 2.7 — Credit support under letters of credit in lieu of a security deposit for an acquisition’s lease - expires 2023 None None 0.5 — Financial guarantees of loans to 8 Canadian-based employees - expires when loan balances are reduced to zero through May 2029 - Principal and interest payments are paid quarterly (1) None 2.4 — $ 26.9 $ 12.3 (1) The guarantees are collateralized by shares in minority holdings of our Canadian operating companies.

Insurance Operations (Tables)

Insurance Operations (Tables)	12 Months Ended
	Dec. 31, 2016
Insurance [Abstract]
Summary of Reconciliations of Direct to Net premiums on Written and Earned Basis Related to Wholly Owned Insurance Company Subsidiary	Reconciliations of direct to net premiums, on a written and earned basis, for 2016, 2015 and 2014 related to the wholly-owned insurance company subsidiary discussed above are as follows (in millions): 2016 2015 2014 Written Earned Written Earned Written Earned Direct $ 71.8 $ 69.6 $ 71.5 $ 71.7 $ 34.9 $ 2.4 Assumed 5.2 4.9 4.4 5.1 2.3 0.2 Ceded (77.0 ) (74.5 ) (75.9 ) (76.8 ) (37.2 ) (2.6 ) Net $ — $ — $ — $ — $ — $ —

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Components of Earnings Before Income Taxes and Provision for Income Taxes	Significant components of earnings before income taxes and the provision for income taxes are as follows (in millions): Year Ended December 31, 2016 2015 2014 Earnings (losses) before income taxes: United States $ 351.3 $ 345.6 $ 288.1 Foreign, principally Australia, Canada, New Zealand and the U.K. 5.6 (52.1 ) 3.4 Total earnings before income taxes $ 356.9 $ 293.5 $ 291.5 Provision (benefit) for income taxes: Federal: Current $ 45.9 $ 43.9 $ 38.8 Deferred (146.7 ) (139.4 ) (96.6 ) (100.8 ) (95.5 ) (57.8 ) State and local: Current 8.4 18.9 19.5 Deferred (0.3 ) (3.3 ) (1.1 ) 8.1 15.6 18.4 Foreign: Current 22.4 22.9 30.5 Deferred (17.8 ) (38.6 ) (27.1 ) 4.6 (15.7 ) 3.4 Total benefit for income taxes $ (88.1 ) $ (95.6 ) $ (36.0 )
Reconciliation of Provision for Income Taxes with Federal Statutory Income Tax Rate	A reconciliation of the provision for income taxes with the U.S. Federal statutory income tax rate is as follows (in millions, except percentages): Year Ended December 31, 2016 2015 2014 Amount % of Amount % of Amount % of Federal statutory rate $ 124.9 35.0 $ 102.7 35.0 $ 102.0 35.0 State income taxes - net of Federal benefit 5.3 1.5 10.2 3.5 12.0 4.1 Differences related to non U.S. operations (34.1 ) (9.6 ) (22.6 ) (7.7 ) (11.2 ) (3.8 ) Alternative energy, foreign and other tax credits (194.4 ) (54.5 ) (181.3 ) (61.8 ) (145.5 ) (49.9 ) Other permanent differences (4.8 ) (1.3 ) (4.9 ) (1.7 ) (2.5 ) (0.9 ) Nondeductible employee compensation — — — — 5.4 1.9 Changes in unrecognized tax benefits 2.2 0.6 3.0 1.0 2.4 0.8 Change in valuation allowance 14.0 3.9 1.7 0.6 — — Change in U.K. tax rate (1.5 ) (0.4 ) (4.2 ) (1.4 ) — — Other 0.3 0.1 (0.2 ) (0.1 ) 1.4 0.5 Benefit for income taxes $ (88.1 ) (24.7 ) $ (95.6 ) (32.6 ) $ (36.0 ) (12.3 )
Gross Unrecognized Tax Benefits	A reconciliation of the beginning and ending balances of the total amounts of gross unrecognized tax benefits is as follows (in millions): December 31, 2016 2015 Gross unrecognized tax benefits at January 1 $ 15.7 $ 12.5 Increases in tax positions for current year 2.4 2.9 Settlements (1.4 ) — Lapse in statute of limitations (1.8 ) (1.3 ) Increases in tax positions for prior years 1.8 2.1 Decreases in tax positions for prior years (2.2 ) (0.5 ) Gross unrecognized tax benefits at December 31 $ 14.5 $ 15.7
Deferred Tax Assets and Liabilities	Significant components of our deferred tax assets and liabilities are as follows (in millions): December 31, 2016 2015 Deferred tax assets: Alternative minimum tax and other credit carryforwards $ 477.9 $ 341.6 Accrued and unfunded compensation and employee benefits 219.0 197.0 Amortizable intangible assets 38.8 39.4 Compensation expense related to stock options 16.9 12.6 Accrued liabilities 31.7 34.3 Accrued pension liability 22.9 23.4 Investments 7.7 9.5 Net operating loss carryforwards 20.4 19.2 Capital loss carryforwards 16.0 2.9 Deferred rent liability 8.1 8.7 Other 3.9 7.7 Total deferred tax assets 863.3 696.3 Valuation allowance for deferred tax assets (66.8 ) (52.8 ) Deferred tax assets 796.5 643.5 Deferred tax liabilities: Nondeductible amortizable intangible assets 310.2 307.1 Investment-related partnerships 34.5 28.7 Depreciable fixed assets 18.2 11.7 Hedging instruments 4.1 — Other prepaid items 4.1 4.6 Total deferred tax liabilities 371.1 352.1 Net deferred tax assets $ 425.4 $ 291.4

Accumulated Other Comprehensi46

Accumulated Other Comprehensive Earnings (Tables)	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Earnings (Loss) Attributable to Controlling Interests	The after-tax Pension Foreign Fair Value Accumulated Balance as of January 1, 2014 $ (25.6 ) $ 22.1 $ 0.9 $ (2.6 ) Net change in period (18.6 ) (238.4 ) (1.0 ) (258.0 ) Balance as of December 31, 2014 (44.2 ) (216.3 ) (0.1 ) (260.6 ) Net change in period 1.3 (261.1 ) (2.1 ) (261.9 ) Balance as of December 31, 2015 (42.9 ) (477.4 ) (2.2 ) (522.5 ) Net change in period (4.4 ) (231.8 ) (4.9 ) (241.1 ) Balance as of December 31, 2016 $ (47.3 ) $ (709.2 ) $ (7.1 ) $ (763.6 )

Quarterly Operating Results (47

Quarterly Operating Results (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Operating Results	Quarterly operating results for 2016 and 2015 were as follows (in millions, except per share data): 1st 2nd 3rd 4th 2016 Total revenues $ 1,300.4 $ 1,427.1 $ 1,482.3 $ 1,385.0 Total expenses 1,244.7 1,289.6 1,387.4 1,316.2 Earnings before income taxes $ 55.7 $ 137.5 $ 94.9 $ 68.8 Net earnings attributable to controlling interests $ 46.5 $ 150.0 $ 122.8 $ 95.1 Basic net earnings per share $ 0.26 $ 0.85 $ 0.69 $ 0.53 Diluted net earnings per share $ 0.26 $ 0.84 $ 0.69 $ 0.53 2015 Total revenues $ 1,231.3 $ 1,371.4 $ 1,454.8 $ 1,334.9 Total expenses 1,200.4 1,242.9 1,349.1 1,306.5 Earnings before income taxes $ 30.9 $ 128.5 $ 105.7 $ 28.4 Net earnings attributable to controlling interests $ 21.9 $ 139.3 $ 133.3 $ 62.3 Basic net earnings per share $ 0.13 $ 0.82 $ 0.76 $ 0.35 Diluted net earnings per share $ 0.13 $ 0.81 $ 0.75 $ 0.35

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2016
Segment Reporting [Abstract]
Schedule of Segment Reporting Information by Segment	Financial information relating to our segments for 2016, 2015 and 2014 is as follows (in millions): Year Ended December 31, 2016 Brokerage Risk Management Corporate Total Revenues: Commissions $ 2,439.1 $ — $ — $ 2,439.1 Fees 775.7 717.1 — 1,492.8 Supplemental commissions 147.0 — — 147.0 Contingent commissions 107.2 — — 107.2 Investment income 52.3 1.0 — 53.3 Gains on books of business sales and other 6.6 — — 6.6 Revenue from clean coal activities — — 1,350.1 1,350.1 Other - net gain — — (1.3 ) (1.3 ) Total revenues 3,527.9 718.1 1,348.8 5,594.8 Compensation 2,041.8 424.5 72.6 2,538.9 Operating 600.9 171.4 25.4 797.7 Cost of revenues from clean coal activities — — 1,408.6 1,408.6 Interest — — 109.8 109.8 Depreciation 57.2 27.2 19.2 103.6 Amortization 244.7 2.5 — 247.2 Change in estimated acquisition earnout payables 32.1 — — 32.1 Total expenses 2,976.7 625.6 1,635.6 5,237.9 Earnings (loss) before income taxes 551.2 92.5 (286.8 ) 356.9 Provision (benefit) for income taxes 194.1 35.3 (317.5 ) (88.1 ) Net earnings 357.1 57.2 30.7 445.0 Net earnings attributable to noncontrolling interests 3.6 — 27.0 30.6 Net earnings attributable to controlling interests $ 353.5 $ 57.2 $ 3.7 $ 414.4 Net foreign exchange gain $ 2.9 $ — $ 0.1 $ 3.0 Revenues: United States $ 2,334.4 $ 610.3 $ 1,327.9 $ 4,272.6 United Kingdom 686.5 25.6 — 712.1 Australia 172.5 73.0 — 245.5 Canada 134.1 4.1 — 138.2 New Zealand 120.7 5.1 — 125.8 Other foreign 79.7 — 20.9 100.6 Total revenues $ 3,527.9 $ 718.1 $ 1,348.8 $ 5,594.8 At December 31, 2016 Identifiable assets: United States $ 4,393.6 $ 540.5 $ 1,622.2 $ 6,556.3 United Kingdom 2,321.9 61.8 — 2,383.7 Australia 894.4 56.9 — 951.3 Canada 573.3 2.8 — 576.1 New Zealand 668.9 4.4 — 673.3 Other foreign 331.3 — 17.6 348.9 Total identifiable assets $ 9,183.4 $ 666.4 $ 1,639.8 $ 11,489.6 Goodwill - net $ 3,736.9 $ 28.1 $ 2.8 $ 3,767.8 Amortizable intangible assets - net 1,613.6 13.7 — 1,627.3 Year Ended December 31, 2015 Brokerage Risk Management Corporate Total Revenues: Commissions $ 2,338.7 $ — $ — $ 2,338.7 Fees 705.8 726.5 — 1,432.3 Supplemental commissions 125.5 — — 125.5 Contingent commissions 93.7 — — 93.7 Investment income 53.6 0.6 — 54.2 Gains on books of business sales and other 6.7 — — 6.7 Revenue from clean coal activities — — 1,310.8 1,310.8 Other - net gain — — 30.5 30.5 Total revenues 3,324.0 727.1 1,341.3 5,392.4 Compensation 1,939.7 427.2 62.0 2,428.9 Operating 638.1 180.8 21.8 840.7 Cost of revenues from clean coal activities — — 1,351.5 1,351.5 Interest — — 103.0 103.0 Depreciation 54.4 24.3 15.2 93.9 Amortization 237.3 3.0 — 240.3 Change in estimated acquisition earnout payables 41.1 (0.5 ) — 40.6 Total expenses 2,910.6 634.8 1,553.5 5,098.9 Earnings (loss) before income taxes 413.4 92.3 (212.2 ) 293.5 Provision (benefit) for income taxes 145.3 35.1 (276.0 ) (95.6 ) Net earnings 268.1 57.2 63.8 389.1 Net earnings attributable to noncontrolling interests 1.7 — 30.6 32.3 Net earnings attributable to controlling interests $ 266.4 $ 57.2 $ 33.2 $ 356.8 Net foreign exchange gain (loss) $ (0.2 ) $ — $ 0.4 $ 0.2 Revenues: United States $ 2,122.1 $ 591.8 $ 1,327.5 $ 4,041.4 United Kingdom 738.5 28.4 — 766.9 Australia 157.3 99.4 — 256.7 Canada 133.1 3.5 — 136.6 New Zealand 118.6 4.0 — 122.6 Other foreign 54.4 — 13.8 68.2 Total revenues $ 3,324.0 $ 727.1 $ 1,341.3 $ 5,392.4 At December 31, 2015 Identifiable assets: United States $ 4,092.8 $ 525.2 $ 1,264.9 $ 5,882.9 United Kingdom 2,580.0 72.1 — 2,652.1 Australia 895.8 55.6 — 951.4 Canada 575.0 3.1 — 578.1 New Zealand 623.1 4.1 — 627.2 Other foreign 203.0 — 19.1 222.1 Total identifiable assets $ 8,969.7 $ 660.1 $ 1,284.0 $ 10,913.8 Goodwill - net $ 3,635.6 $ 27.3 $ — $ 3,662.9 Amortizable intangible assets - net 1,677.8 21.0 — 1,698.8 Year Ended December 31, 2014 Brokerage Risk Corporate Total Revenues: Commissions $ 2,083.0 $ — $ — $ 2,083.0 Fees 577.0 681.3 — 1,258.3 Supplemental commissions 104.0 — — 104.0 Contingent commissions 84.7 — — 84.7 Investment income 40.3 1.0 — 41.3 Gains on books of business sales and other 7.3 — — 7.3 Revenue from clean coal activities — — 1,029.5 1,029.5 Other - net gain — — 18.4 18.4 Total revenues 2,896.3 682.3 1,047.9 4,626.5 Compensation 1,703.1 414.2 50.3 2,167.6 Operating 530.1 176.4 36.6 743.1 Cost of revenues from clean coal activities — — 1,058.9 1,058.9 Interest — — 89.0 89.0 Depreciation 44.4 21.2 3.8 69.4 Amortization 186.3 3.2 — 189.5 Change in estimated acquisition earnout payables 17.6 (0.1 ) — 17.5 Total expenses 2,481.5 614.9 1,238.6 4,335.0 Earnings (loss) before income taxes 414.8 67.4 (190.7 ) 291.5 Provision (benefit) for income taxes 151.0 25.3 (212.3 ) (36.0 ) Net earnings 263.8 42.1 21.6 327.5 Net earnings attributable to noncontrolling interests 0.9 — 23.2 24.1 Net earnings (loss) attributable to controlling interests $ 262.9 $ 42.1 $ (1.6 ) $ 303.4 Net foreign exchange gain (loss) $ 1.1 $ — $ (0.6 ) $ 0.5 Revenues: United States $ 1,873.3 $ 532.6 $ 1,036.9 $ 3,442.8 United Kingdom 696.8 29.4 — 726.2 Australia 122.4 114.2 — 236.6 Canada 81.8 3.2 — 85.0 New Zealand 78.4 2.9 — 81.3 Other foreign 43.6 — 11.0 54.6 Total revenues $ 2,896.3 $ 682.3 $ 1,047.9 $ 4,626.5 At December 31, 2014 Identifiable assets: United States $ 3,557.1 $ 457.5 $ 1,032.0 $ 5,046.6 United Kingdom 2,376.4 74.0 — 2,450.4 Australia 992.2 39.0 — 1,031.2 Canada 639.2 2.8 — 642.0 New Zealand 614.1 1.6 — 615.7 Other foreign 207.2 — 16.9 224.1 Total identifiable assets $ 8,386.2 $ 574.9 $ 1,048.9 $ 10,010.0 Goodwill - net $ 3,427.5 $ 22.1 $ — $ 3,449.6 Amortizable intangible assets - net 1,757.3 18.7 — 1,776.0

Summary of Significant Accoun49

Summary of Significant Accounting Policies - Additional Information (Detail) AUD in Millions	12 Months Ended
	Dec. 31, 2016USD ($)CountrySegmentshares	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2014AUD
Significant Accounting Policies [Line Items]
Number of countries in which the company has operations | Country	33
Number of countries in which the company does business through a network of correspondent brokers and consultants | Country	150
Number of reportable operating segments | Segment	3
Percentage of ownership interest	50.00%
Percentage of variable ownership interest	50.00%
Fee revenue generation period, years	1 year
Allowances for estimated policy cancellations	$ 7,100,000	$ 7,400,000
Allowance for doubtful accounts	$ 12,800,000	13,300,000
Maturity period of short-term investments	90 days or less
Gain on foreign currency derivative investment contract			$ 1,900,000
Foreign currency derivative investment contract | AUD				AUD 400
Premium financing contracts, terms	Premium financing contracts are structured to minimize potential bad debt expense to us. Such receivables are generally considered delinquent after seven days of the payment due date. In normal course, insurance policies are cancelled within one month of the contractual payment due date if the payment remains delinquent.
Outstanding loan receivable	$ 241,200,000	220,200,000
Write-off of amortizable intangible assets	$ 1,800,000	$ 11,500,000	$ 1,800,000
Maximum number of shares purchased by employees | shares	200,000
Minimum [Member]
Significant Accounting Policies [Line Items]
Percentage of ownership interest	1.00%
Maximum [Member]
Significant Accounting Policies [Line Items]
Percentage of ownership interest	50.00%
Employee Stock Purchase Plan [Member]
Significant Accounting Policies [Line Items]
Shares authorized | shares	8,000,000
Percentage of employees contribution	15.00%
Purchase price of common stock, percentage	95.00%
Aggregate fair market value of shares purchased	$ 25,000
Maximum number of shares purchased by employees | shares	2,000
Shares available for grant | shares	7,500,000
Expiration Lists [Member] | Minimum [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives of intangibles assets, years	3 years
Expiration Lists [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives of intangibles assets, years	15 years
Non-Compete Agreements [Member] | Minimum [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives of intangibles assets, years	3 years
Non-Compete Agreements [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives of intangibles assets, years	5 years
Trade Names [Member] | Minimum [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives of intangibles assets, years	5 years
Trade Names [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives of intangibles assets, years	15 years

Summary of Significant Accoun50

Summary of Significant Accounting Policies - Summary of Estimated Useful Life of Fixed Assets (Detail)	12 Months Ended
	Dec. 31, 2016
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives, years	Shorter of the lease term or useful life of the asset
Refined Fuel Plants [Member]
Property, Plant and Equipment [Line Items]
Useful life, years	10 years
Minimum [Member] | Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Useful life, years	3 years
Minimum [Member] | Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Useful life, years	3 years
Minimum [Member] | Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Useful life, years	3 years
Minimum [Member] | Software [Member]
Property, Plant and Equipment [Line Items]
Useful life, years	3 years
Minimum [Member] | Building [Member]
Property, Plant and Equipment [Line Items]
Useful life, years	15 years
Maximum [Member] | Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Useful life, years	5 years
Maximum [Member] | Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Useful life, years	10 years
Maximum [Member] | Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Useful life, years	10 years
Maximum [Member] | Software [Member]
Property, Plant and Equipment [Line Items]
Useful life, years	5 years
Maximum [Member] | Building [Member]
Property, Plant and Equipment [Line Items]
Useful life, years	40 years

Effect of New Accounting Pron51

Effect of New Accounting Pronouncements - Additional Information (Detail) - Reclassification [Member] $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Debt issuance costs	$ 3.3
Amount of noncurrent deferred tax assets increased	122.1
Amount other noncurrent liabilities increased	$ 4.6

Business Combinations - Acquisi

Business Combinations - Acquisition Method for Recording Business Combinations (Detail) shares in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)shares
Business Acquisition [Line Items]
Common Shares Issued | shares	1,850
Common Share Value	$ 75,900,000
Cash Paid	248,000,000
Accrued Liability	9,100,000
Escrow Deposited	22,200,000
Recorded Earnout Payable	44,500,000
Total Recorded Purchase Price	399,700,000
Maximum Potential Earnout Payable	107,500,000
Bomford, Couch & Wilson, Inc. [Member]
Business Acquisition [Line Items]
Cash Paid	900,000
Recorded Earnout Payable	1,400,000
Total Recorded Purchase Price	2,300,000
Maximum Potential Earnout Payable	$ 2,100,000
White & Company Insurance, Inc. [Member]
Business Acquisition [Line Items]
Common Shares Issued | shares	494
Common Share Value	$ 17,400,000
Escrow Deposited	1,900,000
Total Recorded Purchase Price	19,300,000
Joseph Distel & Company, Inc. [Member]
Business Acquisition [Line Items]
Cash Paid	1,300,000
Escrow Deposited	200,000
Total Recorded Purchase Price	1,500,000
Vincent L. Braband Insurance, Inc. [Member]
Business Acquisition [Line Items]
Cash Paid	3,000,000
Escrow Deposited	300,000
Recorded Earnout Payable	400,000
Total Recorded Purchase Price	3,700,000
Maximum Potential Earnout Payable	1,100,000
Kane's Insurance Management Operations (KIM) [Member]
Business Acquisition [Line Items]
Cash Paid	30,800,000
Total Recorded Purchase Price	30,800,000
Capitol Benefits Group, Inc. [Member]
Business Acquisition [Line Items]
Cash Paid	3,300,000
Escrow Deposited	100,000
Recorded Earnout Payable	400,000
Total Recorded Purchase Price	3,800,000
Maximum Potential Earnout Payable	2,800,000
Charles Allen Agency, Inc. [Member]
Business Acquisition [Line Items]
Cash Paid	2,800,000
Escrow Deposited	200,000
Recorded Earnout Payable	200,000
Total Recorded Purchase Price	3,200,000
Maximum Potential Earnout Payable	700,000
Hagan Newkirk Financial Services, Inc. [Member]
Business Acquisition [Line Items]
Cash Paid	4,300,000
Escrow Deposited	100,000
Recorded Earnout Payable	900,000
Total Recorded Purchase Price	5,300,000
Maximum Potential Earnout Payable	$ 3,100,000
Insurance Plans Agency, Inc. [Member]
Business Acquisition [Line Items]
Common Shares Issued | shares	51
Common Share Value	$ 2,300,000
Escrow Deposited	100,000
Recorded Earnout Payable	200,000
Total Recorded Purchase Price	2,600,000
Maximum Potential Earnout Payable	1,500,000
KDC Associates, LLC (KDC) [Member]
Business Acquisition [Line Items]
Cash Paid	20,700,000
Escrow Deposited	1,800,000
Recorded Earnout Payable	3,900,000
Total Recorded Purchase Price	26,400,000
Maximum Potential Earnout Payable	$ 7,500,000
Hogan Insurance Services, Inc. [Member]
Business Acquisition [Line Items]
Common Shares Issued | shares	172
Common Share Value	$ 7,400,000
Escrow Deposited	800,000
Recorded Earnout Payable	1,100,000
Total Recorded Purchase Price	9,300,000
Maximum Potential Earnout Payable	$ 2,000,000
McNeary, Inc. (MNI) [Member]
Business Acquisition [Line Items]
Common Shares Issued | shares	572
Common Share Value	$ 22,000,000
Escrow Deposited	5,000,000
Recorded Earnout Payable	400,000
Total Recorded Purchase Price	27,400,000
Maximum Potential Earnout Payable	5,500,000
Ashmore & Associates Insurance Agency, LLC (AAI) [Member]
Business Acquisition [Line Items]
Cash Paid	7,700,000
Escrow Deposited	400,000
Recorded Earnout Payable	600,000
Total Recorded Purchase Price	8,700,000
Maximum Potential Earnout Payable	$ 1,700,000
KRW Insurance Agency, Inc. (KRW) [Member]
Business Acquisition [Line Items]
Common Shares Issued | shares	139
Common Share Value	$ 5,900,000
Escrow Deposited	700,000
Recorded Earnout Payable	1,000,000
Total Recorded Purchase Price	7,600,000
Maximum Potential Earnout Payable	1,600,000
Buchholz Planning Corporation (BPC) [Member]
Business Acquisition [Line Items]
Cash Paid	3,900,000
Escrow Deposited	100,000
Recorded Earnout Payable	2,500,000
Total Recorded Purchase Price	6,500,000
Maximum Potential Earnout Payable	6,000,000
Blue Horizon Insurance Services Inc [Member]
Business Acquisition [Line Items]
Cash Paid	3,400,000
Escrow Deposited	400,000
Recorded Earnout Payable	500,000
Total Recorded Purchase Price	4,300,000
Maximum Potential Earnout Payable	1,000,000
Brim AB [Member]
Business Acquisition [Line Items]
Cash Paid	23,500,000
Accrued Liability	6,500,000
Total Recorded Purchase Price	30,000,000
Gabor Insurance Services Inc [Member]
Business Acquisition [Line Items]
Cash Paid	14,100,000
Escrow Deposited	500,000
Total Recorded Purchase Price	$ 14,600,000
Victory Insurance Agency Inc [Member]
Business Acquisition [Line Items]
Common Shares Issued | shares	422
Common Share Value	$ 20,900,000
Accrued Liability	2,300,000
Recorded Earnout Payable	2,600,000
Total Recorded Purchase Price	25,800,000
Maximum Potential Earnout Payable	4,500,000
Orb Financial Services Limited [Member]
Business Acquisition [Line Items]
Cash Paid	3,100,000
Escrow Deposited	400,000
Recorded Earnout Payable	2,000,000
Total Recorded Purchase Price	5,500,000
Maximum Potential Earnout Payable	2,700,000
Altman & Cronin Benefit Consultants, LLC (ACB) [Member]
Business Acquisition [Line Items]
Cash Paid	31,400,000
Escrow Deposited	2,500,000
Recorded Earnout Payable	6,600,000
Total Recorded Purchase Price	40,500,000
Maximum Potential Earnout Payable	19,300,000
Regency Insurance Group, Inc. (RIG) [Member]
Business Acquisition [Line Items]
Cash Paid	19,200,000
Escrow Deposited	1,000,000
Total Recorded Purchase Price	20,200,000
Argentis (ARG) [Member]
Business Acquisition [Line Items]
Cash Paid	15,100,000
Accrued Liability	200,000
Escrow Deposited	2,200,000
Recorded Earnout Payable	5,000,000
Total Recorded Purchase Price	22,500,000
Maximum Potential Earnout Payable	14,500,000
Group Insurance Associates, Inc. [Member]
Business Acquisition [Line Items]
Cash Paid	9,200,000
Escrow Deposited	300,000
Recorded Earnout Payable	3,000,000
Total Recorded Purchase Price	12,500,000
Maximum Potential Earnout Payable	6,500,000
MW Bagnall Company [Member]
Business Acquisition [Line Items]
Cash Paid	5,300,000
Escrow Deposited	200,000
Recorded Earnout Payable	1,100,000
Total Recorded Purchase Price	6,600,000
Maximum Potential Earnout Payable	5,400,000
National Ethics Association [Member]
Business Acquisition [Line Items]
Cash Paid	15,600,000
Escrow Deposited	1,700,000
Total Recorded Purchase Price	17,300,000
Eleven Other Acquisitions [Member]
Business Acquisition [Line Items]
Cash Paid	29,400,000
Accrued Liability	100,000
Escrow Deposited	1,300,000
Recorded Earnout Payable	10,700,000
Total Recorded Purchase Price	41,500,000
Maximum Potential Earnout Payable	$ 18,000,000

Business Combinations - Acqui53

Business Combinations - Acquisition Method for Recording Business Combinations (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2016
Bomford, Couch & Wilson, Inc. [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Feb. 1, 2016
White & Company Insurance, Inc. [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Feb. 1, 2016
Joseph Distel & Company, Inc. [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Mar. 1, 2016
Vincent L. Braband Insurance, Inc. [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Mar. 1, 2016
Kane's Insurance Management Operations (KIM) [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Mar. 31, 2016
Capitol Benefits Group, Inc. [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Apr. 1, 2016
Charles Allen Agency, Inc. [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Apr. 1, 2016
Hagan Newkirk Financial Services, Inc. [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Apr. 1, 2016
Insurance Plans Agency, Inc. [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Apr. 1, 2016
KDC Associates, LLC (KDC) [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Apr. 1, 2016
Hogan Insurance Services, Inc. [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	May 1, 2016
McNeary, Inc. (MNI) [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	May 1, 2016
Ashmore & Associates Insurance Agency, LLC (AAI) [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	May 1, 2016
KRW Insurance Agency, Inc. (KRW) [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Jun. 1, 2016
Buchholz Planning Corporation (BPC) [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Jun. 1, 2016
Blue Horizon Insurance Services Inc [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Jul. 1, 2016
Brim AB [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Jul. 1, 2016
Gabor Insurance Services Inc [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Jul. 1, 2016
Victory Insurance Agency Inc [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Jul. 1, 2016
Orb Financial Services Limited [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Aug. 1, 2016
Altman & Cronin Benefit Consultants, LLC (ACB) [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Nov. 1, 2016
Regency Insurance Group, Inc. (RIG) [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Nov. 1, 2016
Argentis (ARG) [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Nov. 1, 2016
Group Insurance Associates, Inc. [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Dec. 1, 2016
MW Bagnall Company [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Dec. 1, 2016
National Ethics Association [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Dec. 1, 2016
Eleven Other Acquisitions [Member]
Business Acquisition [Line Items]
Effective Year of Acquisition	2,016

Business Combinations - Additio

Business Combinations - Additional Information (Detail)	12 Months Ended			180 Months Ended
	Dec. 31, 2016USD ($)Entity	Dec. 31, 2015USD ($)Entity	Dec. 31, 2014USD ($)Entity	Dec. 31, 2016USD ($)Entity
Business Acquisition [Line Items]
Accretion of the discount on acquisition	$ 16,900,000	$ 16,200,000	$ 14,500,000
Number of companies acquired | Entity	101	105	67	420
Aggregate amount of maximum earnout obligations related to acquisitions	$ 527,200,000	$ 565,400,000
Aggregate amount of maximum earnout obligations related to acquisitions, recorded in consolidated balance sheet	242,300,000	229,700,000
Income (expense) related to net adjustments to estimated fair value of liability for earnout obligations	(15,200,000)	(24,400,000)	$ (3,000,000)
Goodwill	225,400,000			$ 225,400,000
Expiration lists	218,100,000			218,100,000
Non-compete agreements	2,800,000			2,800,000
Trade names	400,000			400,000
Total revenues related to acquisitions in the aggregate	5,663,700,000	$ 5,528,600,000
Brokerage and Risk Management [Member]
Business Acquisition [Line Items]
Goodwill	225,400,000			225,400,000
Expiration lists	218,100,000			218,100,000
Non-compete agreements	2,800,000			2,800,000
Trade names	$ 400,000			400,000
2016 Acquisitions [Member] | Market Approach Valuation Technique [Member] | Minimum [Member]
Business Acquisition [Line Items]
Revenue growth rate	3.50%
Discount rate	8.00%
2016 Acquisitions [Member] | Market Approach Valuation Technique [Member] | Maximum [Member]
Business Acquisition [Line Items]
Revenue growth rate	16.00%
Discount rate	9.50%
2016 Acquisitions [Member] | Income Approach Valuation Technique [Member] | Minimum [Member]
Business Acquisition [Line Items]
Revenue growth rate	1.00%
Discount rate	12.00%
Attrition rate	3.00%
2016 Acquisitions [Member] | Income Approach Valuation Technique [Member] | Maximum [Member]
Business Acquisition [Line Items]
Revenue growth rate	2.50%
Discount rate	19.00%
Attrition rate	12.50%
Business Acquisition [Member]
Business Acquisition [Line Items]
Annualized revenue of business acquisitions	$ 137,900,000
Total revenues related to acquisitions in the aggregate	73,300,000
Net earnings	4,200,000
Business Acquisition [Member] | Brokerage [Member]
Business Acquisition [Line Items]
Expiration lists	218,100,000			218,100,000
Non-compete agreements	2,800,000			2,800,000
Trade names	400,000			400,000
Deferred tax liability	27,300,000			27,300,000
Goodwill related to nondeductible amortizable intangible assets	27,300,000
Business Acquisition [Member] | Expiration Lists [Member] | Brokerage [Member]
Business Acquisition [Line Items]
Business acquisition not deductible for income tax purposes	92,600,000			92,600,000
Business Acquisition [Member] | Non-Compete Agreements [Member] | Brokerage [Member]
Business Acquisition [Line Items]
Business acquisition not deductible for income tax purposes	$ 1,400,000			$ 1,400,000

Business Combinations - Summary

Business Combinations - Summary of Estimated Fair Values of Net Assets Acquired (Detail) $ in Millions	Dec. 31, 2016USD ($)
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Cash	$ 13.3
Other current assets	67.2
Fixed assets	3.6
Noncurrent assets	1.5
Goodwill	225.4
Expiration lists	218.1
Non-compete agreements	2.8
Trade names	0.4
Total assets acquired	532.3
Current liabilities	67
Noncurrent liabilities	65.6
Total liabilities assumed	132.6
Total net assets acquired	399.7
Kane's Insurance Management Operations (KIM) [Member]
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Cash	2.2
Other current assets	1.8
Fixed assets	0.4
Noncurrent assets	1.2
Goodwill	9.2
Expiration lists	20
Total assets acquired	34.8
Current liabilities	3.9
Noncurrent liabilities	0.1
Total liabilities assumed	4
Total net assets acquired	30.8
KDC Associates, LLC (KDC) [Member]
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Cash	0.3
Other current assets	9.3
Fixed assets	0.1
Goodwill	12.1
Expiration lists	13.8
Non-compete agreements	0.1
Total assets acquired	35.7
Current liabilities	8.9
Noncurrent liabilities	0.4
Total liabilities assumed	9.3
Total net assets acquired	26.4
McNeary, Inc. (MNI) [Member]
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Cash	3
Other current assets	1.7
Fixed assets	0.1
Goodwill	19.5
Expiration lists	13.8
Non-compete agreements	0.1
Trade names	0.1
Total assets acquired	38.3
Current liabilities	2.2
Noncurrent liabilities	8.7
Total liabilities assumed	10.9
Total net assets acquired	27.4
Brim AB [Member]
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Cash	0.5
Other current assets	36
Fixed assets	0.6
Goodwill	19.7
Expiration lists	14.6
Non-compete agreements	0.6
Trade names	0.3
Total assets acquired	72.3
Current liabilities	33.2
Noncurrent liabilities	9.1
Total liabilities assumed	42.3
Total net assets acquired	30
Victory Insurance Agency Inc [Member]
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Cash	0.2
Other current assets	2.1
Fixed assets	0.1
Goodwill	18.5
Expiration lists	11.3
Non-compete agreements	0.4
Total assets acquired	32.6
Current liabilities	2.2
Noncurrent liabilities	4.6
Total liabilities assumed	6.8
Total net assets acquired	25.8
Altman & Cronin Benefit Consultants, LLC (ACB) [Member]
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Other current assets	1.3
Goodwill	19.9
Expiration lists	18.9
Non-compete agreements	0.4
Total assets acquired	40.5
Total net assets acquired	40.5
Regency Insurance Group, Inc. (RIG) [Member]
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Cash	0.6
Other current assets	0.6
Goodwill	10.5
Expiration lists	9.3
Non-compete agreements	0.2
Total assets acquired	21.2
Current liabilities	1
Total liabilities assumed	1
Total net assets acquired	20.2
Argentis (ARG) [Member]
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Cash	1.4
Other current assets	0.4
Noncurrent assets	0.3
Goodwill	12.1
Expiration lists	24.1
Total assets acquired	38.3
Current liabilities	0.8
Noncurrent liabilities	15
Total liabilities assumed	15.8
Total net assets acquired	22.5
Twenty-nine Other Acquisitions [Member]
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Cash	5.1
Other current assets	14
Fixed assets	2.3
Goodwill	103.9
Expiration lists	92.3
Non-compete agreements	1
Total assets acquired	218.6
Current liabilities	14.8
Noncurrent liabilities	27.7
Total liabilities assumed	42.5
Total net assets acquired	$ 176.1

Business Combinations - Summa56

Business Combinations - Summary of Unaudited Pro Forma Historical Results (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Business Combinations [Abstract]
Total revenues	$ 5,663.7	$ 5,528.6
Net earnings attributable to controlling interests	$ 420.6	$ 361.9
Basic earnings per share	$ 2.36	$ 2.08
Diluted earnings per share	$ 2.35	$ 2.07

Other Current Assets - Summary

Other Current Assets - Summary of Major Classes of Other Current Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Premium finance advances and loans	$ 241.2	$ 220.2
Accrued supplemental, direct bill and other receivables	177.2	181.1
Refined coal production related receivables	136.9	108.1
Prepaid expenses	78.4	77.8
Total other current assets	$ 633.7	$ 587.2

Other Current Assets - Addition

Other Current Assets - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Collateralized delinquency period of receivables	7 days

Fixed Assets - Summary of Fixed

Fixed Assets - Summary of Fixed Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Property Plant and Equipment Useful Life and Values [Abstract]
Office equipment	$ 22.5	$ 21.1
Furniture and fixtures	96.7	92.7
Leasehold improvements	107.8	106.1
Computer equipment	131.4	143.4
Land and buildings - corporate headquarters	141.7
Software	268.4	228.3
Other	10	10
Work in process - includes $30.0 million related to our corporate headquarters in 2015	10.6	46.3
Gross fixed assets	789.1	647.9
Accumulated depreciation	(411.5)	(398.9)
Net fixed assets	$ 377.6	$ 249

Fixed Assets - Summary of Fix60

Fixed Assets - Summary of Fixed Assets (Parenthetical) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
New Corporate Headquarters [Member]
Property, Plant and Equipment [Line Items]
Construction in progress, capitalized expenditure incurred	$ 30

Fixed Assets - Additional Infor

Fixed Assets - Additional Information (Detail) $ in Millions	3 Months Ended
	Dec. 31, 2016USD ($)
New Corporate Headquarters and Other Projects [Member] | Fixed Assets [Member]
Property, Plant and Equipment [Line Items]
Reclassification of work in progress	$ 46.3

Intangible Assets - Carrying Am

Intangible Assets - Carrying Amount of Goodwill Allocated by Domestic and Foreign Operations (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Line Items]
Total goodwill - net	$ 3,767.8	$ 3,662.9	$ 3,449.6
Unites States [Member]
Goodwill [Line Items]
Total goodwill - net	2,138.5	1,970.4
United Kingdom [Member]
Goodwill [Line Items]
Total goodwill - net	666.5	782.8
Canada [Member]
Goodwill [Line Items]
Total goodwill - net	292.2	282.6
Australia [Member]
Goodwill [Line Items]
Total goodwill - net	382.7	380.1
New Zealand [Member]
Goodwill [Line Items]
Total goodwill - net	205.3	204.5
Other Foreign [Member]
Goodwill [Line Items]
Total goodwill - net	82.6	42.5
Brokerage [Member]
Goodwill [Line Items]
Total goodwill - net	3,736.9	3,635.6	3,427.5
Brokerage [Member] | Unites States [Member]
Goodwill [Line Items]
Total goodwill - net	2,115	1,946.9
Brokerage [Member] | United Kingdom [Member]
Goodwill [Line Items]
Total goodwill - net	662.2	779.3
Brokerage [Member] | Canada [Member]
Goodwill [Line Items]
Total goodwill - net	292.2	282.6
Brokerage [Member] | Australia [Member]
Goodwill [Line Items]
Total goodwill - net	382.7	380.1
Brokerage [Member] | New Zealand [Member]
Goodwill [Line Items]
Total goodwill - net	205	204.2
Brokerage [Member] | Other Foreign [Member]
Goodwill [Line Items]
Total goodwill - net	79.8	42.5
Risk Management Services Management Segment [Member]
Goodwill [Line Items]
Total goodwill - net	28.1	27.3	$ 22.1
Risk Management Services Management Segment [Member] | Unites States [Member]
Goodwill [Line Items]
Total goodwill - net	23.5	23.5
Risk Management Services Management Segment [Member] | United Kingdom [Member]
Goodwill [Line Items]
Total goodwill - net	4.3	3.5
Risk Management Services Management Segment [Member] | New Zealand [Member]
Goodwill [Line Items]
Total goodwill - net	0.3	$ 0.3
Corporate [Member]
Goodwill [Line Items]
Total goodwill - net	2.8
Corporate [Member] | Other Foreign [Member]
Goodwill [Line Items]
Total goodwill - net	$ 2.8

Intangible Assets - Changes in

Intangible Assets - Changes in Carrying Amount of Goodwill (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Line Items]
Beginning Balance	$ 3,662.9	$ 3,449.6
Goodwill acquired during the year	225.4	354.6
Goodwill adjustments related to appraisals and other acquisition adjustments	3.4	25.3
Foreign currency translation adjustments during the year	(123.9)	(166.6)
Ending Balance	3,767.8	3,662.9
Brokerage [Member]
Goodwill [Line Items]
Beginning Balance	3,635.6	3,427.5
Goodwill acquired during the year	222.6	352.6
Goodwill related to transfers of operations between segments		(3.4)
Goodwill adjustments related to appraisals and other acquisition adjustments	1.8	25.3
Foreign currency translation adjustments during the year	(123.1)	(166.4)
Ending Balance	3,736.9	3,635.6
Risk Management Services Management Segment [Member]
Goodwill [Line Items]
Beginning Balance	27.3	22.1
Goodwill acquired during the year		2
Goodwill related to transfers of operations between segments		3.4
Goodwill adjustments related to appraisals and other acquisition adjustments	1.6
Foreign currency translation adjustments during the year	(0.8)	(0.2)
Ending Balance	28.1	$ 27.3
Corporate [Member]
Goodwill [Line Items]
Goodwill acquired during the year	2.8
Ending Balance	$ 2.8

Intangible Assets - Major Class

Intangible Assets - Major Classes of Amortizable Intangible Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets, net	$ 1,627.3	$ 1,698.8	$ 1,776
Expiration Lists [Member]
Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets, gross	2,757.6	2,613.3
Accumulated amortization	(1,143)	(934.7)
Amortizable intangible assets, net	1,614.6	1,678.6
Non-Compete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets, gross	49.3	43.7
Accumulated amortization	(42.1)	(34.8)
Amortizable intangible assets, net	7.2	8.9
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets, gross	24	25.7
Accumulated amortization	(18.5)	(14.4)
Amortizable intangible assets, net	$ 5.5	$ 11.3

Intangible Assets - Estimated A

Intangible Assets - Estimated Aggregate Amortization Expense (Detail) $ in Millions	Dec. 31, 2016USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2,017	$ 239.6
2,018	226.8
2,019	213.1
2,020	197
2,021	174.5
Total	$ 1,051

Credit and Other Debt Agreeme66

Credit and Other Debt Agreements - Summary of Corporate and Other Debt (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Semi-annual payments of interest	$ 2,853.6	$ 2,457
Less unamortized debt acquisition costs on Note Purchase Agreements	(5.4)	(3.3)
Semi-annual payments of interest, Net	2,848.2	2,453.7
Premium Financing Debt Facility [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	125.6	137
Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	2,450	2,125
Fixed Rate of 6.44%, Balloon Due 2017 [Member] | Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	300	300
Fixed Rate of 5.85%, $50 Million Due in 2018 and 2019 [Member] | Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	100	150
Fixed Rate of 2.80%, Balloon Due 2018 [Member] | Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	50	50
Fixed Rate of 3.20%, Balloon Due 2019 [Member] | Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	50	50
Fixed Rate of 3.99%, Balloon Due 2020 [Member] | Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	50	50
Fixed Rate of 3.48%, Balloon Due 2020 [Member] | Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	50	50
Fixed Rate of 5.18%, Balloon Due 2021 [Member] | Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	75	75
Fixed rate of 3.69%, Balloon Due 2022 [Member] | Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	200	200
Fixed Rate of 5.49%, Balloon Due 2023 [Member] | Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	50	50
Fixed Rate of 4.13%, Balloon Due 2023 [Member] | Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	200	200
Fixed Rate of 4.58% Balloon Due 2024 [Member] | Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	325	325
Fixed Rate of 4.31%, Balloon Due 2025 [Member] | Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	200	200
Fixed Rate of 4.73% Balloon Due 2026 [Member] | Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	175	175
Fixed Rate of 4.36%, Balloon Due 2026 [Member] | Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	150	150
Fixed Rate of 4.40%, Balloon Due 2026 [Member] | Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	175
Fixed Rate of 3.46%, Balloon Due 2027 [Member] | Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	100
Fixed Rate of 4.55%, Balloon Due 2028 [Member] | Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	75
Fixed Rate of 4.98% Balloon Due 2029 [Member] | Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	100	100
Fixed Rate of 4.70%, Balloon Due 2031 [Member] | Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	25
Prime or LIBOR plus up to 1.45%, expires April 8, 2016 [Member] | Multi Currency Credit Agreement [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	278	195
Interbank rates plus 1.05%, Expires May 18, 2017 [Member] | AUD denominated tranche [Member] | Facility B [Member] | Premium Financing Debt Facility [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	100.7	101.2
Interbank rates plus 1.05%, Expires May 18, 2017 [Member] | NZD denominated tranche [Member] | Facility B [Member] | Premium Financing Debt Facility [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	9	8.5
Interbank rates plus 0.55%, Expires May 18, 2017 [Member] | AUD denominated tranche [Member] | Facility C and D [Member] | Premium Financing Debt Facility [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	5.6	17.2
Interbank rates plus 0.55%, Expires May 18, 2017 [Member] | NZD denominated tranche [Member] | Facility C and D [Member] | Premium Financing Debt Facility [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	$ 10.3	$ 10.1

Credit and Other Debt Agreeme67

Credit and Other Debt Agreements - Summary of Corporate and Other Debt (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Premium Financing Debt Facility [Member]
Debt Instrument [Line Items]
Periodic payments of interest and principal, expiry date	May 18, 2017	May 18, 2017
Fixed Rate of 6.44%, Balloon Due 2017 [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest	6.44%	6.44%
Principal payments, year due	2,017	2,017
Fixed Rate of 5.85%, $50 Million Due in 2018 and 2019 [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest	5.85%	5.85%
Long-Term debt maturities repayments in 2018	$ 50	$ 50
Long-Term debt maturities repayments in 2019	$ 50	$ 50
Fixed Rate of 2.80%, Balloon Due 2018 [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest	2.80%	2.80%
Principal payments, year due	2,018	2,018
Fixed Rate of 3.20%, Balloon Due 2019 [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest	3.20%	3.20%
Principal payments, year due	2,019	2,019
Fixed Rate of 3.99%, Balloon Due 2020 [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest	3.99%	3.99%
Principal payments, year due	2,020	2,020
Fixed Rate of 3.48%, Balloon Due 2020 [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest	3.48%	3.48%
Principal payments, year due	2,020	2,020
Fixed Rate of 5.18%, Balloon Due 2021 [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest	5.18%	5.18%
Principal payments, year due	2,021	2,021
Fixed rate of 3.69%, Balloon Due 2022 [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest	3.69%	3.69%
Principal payments, year due	2,022	2,022
Fixed Rate of 5.49%, Balloon Due 2023 [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest	5.49%	5.49%
Principal payments, year due	2,023	2,023
Fixed Rate of 4.13%, Balloon Due 2023 [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest	4.13%	4.13%
Principal payments, year due	2,023	2,023
Fixed Rate of 4.58% Balloon Due 2024 [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest	4.58%	4.58%
Principal payments, year due	2,024	2,024
Fixed Rate of 4.31%, Balloon Due 2025 [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest	4.31%	4.31%
Principal payments, year due	2,025	2,025
Fixed Rate of 4.73% Balloon Due 2026 [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest	4.73%	4.73%
Principal payments, year due	2,026	2,026
Fixed Rate of 4.36%, Balloon Due 2026 [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest	4.36%	4.36%
Principal payments, year due	2,026	2,026
Fixed Rate of 4.40%, Balloon Due 2026 [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest	4.40%	4.40%
Principal payments, year due	2,026	2,026
Fixed Rate of 3.46%, Balloon Due 2027 [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest	3.46%	3.46%
Principal payments, year due	2,027	2,027
Fixed Rate of 4.55%, Balloon Due 2028 [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest	4.55%	4.55%
Principal payments, year due	2,028	2,028
Fixed Rate of 4.98% Balloon Due 2029 [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest	4.98%	4.98%
Principal payments, year due	2,029	2,029
Fixed Rate of 4.70%, Balloon Due 2031 [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest	4.70%	4.70%
Principal payments, year due	2,031	2,031
Prime or LIBOR plus up to 1.45%, expires April 8, 2016 [Member] | Credit Agreement [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest	1.45%	1.45%
Periodic payments of interest and principal, expiry date	Apr. 8, 2016	Apr. 8, 2016
First Installment [Member] | Fixed Rate of 5.85%, $50 Million Due in 2018 and 2019 [Member]
Debt Instrument [Line Items]
Principal payments, year due	2,018	2,018
Second Installment [Member] | Fixed Rate of 5.85%, $50 Million Due in 2018 and 2019 [Member]
Debt Instrument [Line Items]
Principal payments, year due	2,019	2,019
Facility B [Member] | Interbank rates plus 1.05%, Expires May 18, 2017 [Member] | Premium Financing Debt Facility [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest	1.05%	1.05%
Facility C and D [Member] | Interbank rates plus 0.55%, Expires May 18, 2017 [Member] | Premium Financing Debt Facility [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest	0.55%	0.55%

Credit and Other Debt Agreeme68

Credit and Other Debt Agreements - Note Purchase Agreements - Additional information (Detail) - USD ($) $ in Millions	Nov. 30, 2016	Dec. 31, 2016	Dec. 31, 2014
Debt Instrument [Line Items]
Notes funded		$ 50	$ 100
Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Cash gain realized from hedging transaction		$ 1
Interest expense expiration period		10 years
Amount payable to redeem the notes, percent of the principal amount		100.00%
Discount rate used to compute the remaining scheduled payments of principal and interest		U.S. Treasury yield plus 0.5%
Note Purchase Agreements [Member] | 6.44% Senior Notes, Series B [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 300
Note payable, semi-annual payments of interest, fixed rate		6.44%
Debt instrument, maturity date		Aug. 3, 2017
Note Purchase Agreements [Member] | 5.85% Senior Notes, Series C [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 150
Note payable, semi-annual payments of interest, fixed rate		5.85%
Note Purchase Agreements [Member] | 5.85% Senior Notes, Series C [Member] | First Installment [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date		Nov. 30, 2016
Note Purchase Agreements [Member] | 5.85% Senior Notes, Series C [Member] | Second Installment [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date		Nov. 30, 2018
Note Purchase Agreements [Member] | 5.85% Senior Notes, Series C [Member] | Third Installment [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date		Nov. 30, 2019
Note Purchase Agreements [Member] | 5.18% Senior Notes, Series D [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 75
Note payable, semi-annual payments of interest, fixed rate		5.18%
Debt instrument, maturity date		Feb. 10, 2021
Note Purchase Agreements [Member] | 5.49% Senior Notes, Series E [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 50
Note payable, semi-annual payments of interest, fixed rate		5.49%
Debt instrument, maturity date		Feb. 10, 2023
Note Purchase Agreements [Member] | 3.99% Senior Notes, Series F [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 50
Note payable, semi-annual payments of interest, fixed rate		3.99%
Debt instrument, maturity date		Jul. 10, 2020
Note Purchase Agreements [Member] | 3.69% Senior Notes Series G [Member] | Private Placement [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date		Jun. 14, 2022
Private placement debt, additional amount committed to borrow		$ 200
Interest rate		3.69%
Note Purchase Agreements [Member] | 4.58% Senior Notes, Series H [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 325
Note payable, semi-annual payments of interest, fixed rate		4.58%
Debt instrument, maturity date		Feb. 27, 2024
Note Purchase Agreements [Member] | 4.73% Senior Notes, Series I [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 175
Note payable, semi-annual payments of interest, fixed rate		4.73%
Debt instrument, maturity date		Feb. 27, 2026
Note Purchase Agreements [Member] | 4.98% Senior Notes, Series J [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 100
Note payable, semi-annual payments of interest, fixed rate		4.98%
Debt instrument, maturity date		Feb. 27, 2029
Note Purchase Agreements [Member] | Senior Notes Series H, I & J [Member]
Debt Instrument [Line Items]
Debt acquisition costs		$ 1.4
Note Purchase Agreements [Member] | 2.80% Senior Notes, Series K [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 50
Note payable, semi-annual payments of interest, fixed rate		2.80%
Debt instrument, maturity date		Jun. 24, 2018
Note Purchase Agreements [Member] | 3.20% Senior Notes, Series L [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 50
Note payable, semi-annual payments of interest, fixed rate		3.20%
Debt instrument, maturity date		Jun. 24, 2019
Note Purchase Agreements [Member] | 3.48% Senior Notes, Series M [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 50
Note payable, semi-annual payments of interest, fixed rate		3.48%
Debt instrument, maturity date		Jun. 24, 2020
Note Purchase Agreements [Member] | 4.13% Senior Notes, Series N [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 200
Note payable, semi-annual payments of interest, fixed rate		4.13%
Debt instrument, maturity date		Jun. 24, 2023
Note Purchase Agreements [Member] | 4.31% Senior Notes, Series O [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 200
Note payable, semi-annual payments of interest, fixed rate		4.31%
Debt instrument, maturity date		Jun. 24, 2025
Note Purchase Agreements [Member] | 4.36% Senior Notes, Series P [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 150
Note payable, semi-annual payments of interest, fixed rate		4.36%
Debt instrument, maturity date		Jun. 24, 2026
Note Purchase Agreements [Member] | Senior Notes Series K, L, M, N, O & P [Member]
Debt Instrument [Line Items]
Debt acquisition costs		$ 2.6
Note Purchase Agreements [Member] | 4.40% Senior Notes, Series Q [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 175
Note payable, semi-annual payments of interest, fixed rate		4.40%
Debt instrument, maturity date		Jun. 2, 2026
Note Purchase Agreements [Member] | 4.55% Senior Notes, Series R [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 75
Note payable, semi-annual payments of interest, fixed rate		4.55%
Debt instrument, maturity date		Jun. 2, 2028
Note Purchase Agreements [Member] | 4.70% Senior Notes, Series S [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 25
Note payable, semi-annual payments of interest, fixed rate		4.70%
Debt instrument, maturity date		Jun. 2, 2031
Note Purchase Agreements [Member] | Senior Notes Series Q, R & S [Member]
Debt Instrument [Line Items]
Debt acquisition costs		$ 1.2
Note Purchase Agreements [Member] | 2016 Maturity of Series C Note [Member]
Debt Instrument [Line Items]
Notes funded	$ 50
Note Purchase Agreements [Member] | 3.46% Senior Notes, Series T [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 100
Note payable, semi-annual payments of interest, fixed rate		3.46%
Debt instrument, maturity date		Dec. 1, 2027

Credit and Other Debt Agreeme69

Credit and Other Debt Agreements - Credit Agreement - Additional information (Detail) NZD in Millions, AUD in Millions	Apr. 08, 2016USD ($)Institution	Dec. 31, 2016USD ($)	Dec. 31, 2016AUD	Dec. 31, 2016NZD	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2016AUD	Dec. 31, 2016NZD
Debt Instrument [Line Items]
Liabilities		$ 7,833,800,000			$ 7,222,300,000
Line of credit facility, increase in additional borrowings		2,740,000,000			$ 849,000,000	$ 1,109,900,000
Long-term debt		$ 26,900,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Date of expire		May 18, 2017	May 18, 2017	May 18, 2017
Interest rate for facility		The interest rates on Facility B are Interbank rates, which vary by tranche, duration and currency, plus a margin of 1.05%. The interest rates on Facilities C and D are 30 day Interbank rates, plus a margin of 0.55%. The annual fee for Facility B is 0.4725% of the undrawn commitments for the two tranches of the facility. The annual fee for Facilities C and D is 0.50% of the total commitments of the facilities.	The interest rates on Facility B are Interbank rates, which vary by tranche, duration and currency, plus a margin of 1.05%. The interest rates on Facilities C and D are 30 day Interbank rates, plus a margin of 0.55%. The annual fee for Facility B is 0.4725% of the undrawn commitments for the two tranches of the facility. The annual fee for Facilities C and D is 0.50% of the total commitments of the facilities.	The interest rates on Facility B are Interbank rates, which vary by tranche, duration and currency, plus a margin of 1.05%. The interest rates on Facilities C and D are 30 day Interbank rates, plus a margin of 0.55%. The annual fee for Facility B is 0.4725% of the undrawn commitments for the two tranches of the facility. The annual fee for Facilities C and D is 0.50% of the total commitments of the facilities.
Debt instrument fair value amount		$ 125,600,000
Credit Facility Two [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, amount outstanding							AUD 139	NZD 13
Line of credit facility, remaining borrowing capacity							11	22
Net borrowings on premium financing debt facility			AUD 150	NZD 35
Additional margin percentage on interest rate		1.05%	1.05%	1.05%
Annual fee percentage		0.4725%	0.4725%	0.4725%
Credit Facility Three [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, amount outstanding | AUD							7.7
Line of credit facility, remaining borrowing capacity							17.3	0.1
Net borrowings on premium financing debt facility | AUD			AUD 25
Additional margin percentage on interest rate		0.55%	0.55%	0.55%
Annual fee percentage		0.50%	0.50%	0.50%
Credit Facility Four [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, amount outstanding | NZD								14.9
Line of credit facility, remaining borrowing capacity							AUD 17.3	NZD 0.1
Net borrowings on premium financing debt facility | NZD				NZD 15
Additional margin percentage on interest rate		0.55%	0.55%	0.55%
Annual fee percentage		0.50%	0.50%	0.50%
Multi Currency Credit Agreement [Member]
Debt Instrument [Line Items]
Number of financial institutions entered in unsecured multicurrency credit agreement | Institution	15
Line of credit facility, maximum amount outstanding during period		$ 1,100,000,000
Debt acquisition costs		2,000,000
Estimated fair value of outstanding borrowings		$ 278,000,000
Multi Currency Credit Agreement [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date	Sep. 19, 2018
Line of credit facility, maximum borrowing capacity	$ 600,000,000
Interest rates on base rate loans		0.00%	0.00%	0.00%
Fixed rate over LIBOR		0.85%	0.85%	0.85%
Annual facility fee of revolving credit facility		0.15%	0.15%	0.15%
Multi Currency Credit Agreement [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date	Apr. 8, 2021
Line of credit facility, maximum borrowing capacity	$ 800,000,000
Interest rates on base rate loans		0.45%	0.45%	0.45%
Fixed rate over LIBOR		1.45%	1.45%	1.45%
Annual facility fee of revolving credit facility		0.30%	0.30%	0.30%
Multi Currency Credit Agreement [Member] | Swing Loan [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 75,000,000
Multi Currency Credit Agreement [Member] | Standby Letters of Credit [Member]
Debt Instrument [Line Items]
Long-term debt, gross		75,000,000
Line of credit facility, amount outstanding		21,100,000
Liabilities		12,300,000
Line of credit facility, fair value of amount outstanding		278,000,000
Line of credit facility, remaining borrowing capacity		500,900,000
Line of credit facility, increase in additional borrowings		53,900,000
Note Purchase Agreements [Member] | Level 3 [Member]
Debt Instrument [Line Items]
Line of credit facility, fair value of amount outstanding		2,545,000,000
Long-term debt		$ 2,450,000,000

Earnings Per Share - Computatio

Earnings Per Share - Computation of Basic and Diluted Net EPS (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Net earnings attributable to controlling interests	$ 95.1	$ 122.8	$ 150	$ 46.5	$ 62.3	$ 133.3	$ 139.3	$ 21.9	$ 414.4	$ 356.8	$ 303.4
Weighted average number of common shares outstanding									177.6	172.2	152.9
Dilutive effect of stock options using the treasury stock method									0.8	1	1.4
Weighted average number of common and common equivalent shares outstanding									178.4	173.2	154.3
Basic net earnings per share									$ 2.33	$ 2.07	$ 1.98
Diluted net earnings per share									$ 2.32	$ 2.06	$ 1.97

Earnings Per Share - Additional

Earnings Per Share - Additional information (Detail) - shares shares in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Options to purchase common stock shares outstanding	5.9	3.5	1.6

Stock Option Plans - Additional

Stock Option Plans - Additional information (Detail) - USD ($)	Mar. 17, 2016	Mar. 11, 2015	Mar. 12, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock Option Plans [Line Items]
Maximum number of shares available				479,167	394,975	376,541
Maximum number of shares granted during any fiscal year to any person				200,000
Number of years options expire, maximum				7 years	7 years	7 years
Compensation expense related to stock option grants				$ 14,700,000	$ 11,200,000	$ 9,500,000
Total intrinsic value of options exercised				19,300,000	$ 27,000,000	$ 30,500,000
Total unrecognized compensation cost related to nonvested options				$ 41,400,000
Weighted average period, years				4 years
Officer and Key Employees [Member]
Stock Option Plans [Line Items]
Shares available for grant	2,576,000	1,941,000	1,923,000
Stock options granted, exercise percentage, on the third anniversary date of the grant	34.00%	34.00%	34.00%
Stock options granted, exercise percentage, on the fourth anniversary date of the grant	33.00%	33.00%	33.00%
Stock options granted, exercise percentage, on the fifth anniversary date of the grant	33.00%	33.00%	33.00%
Long Term Incentive Plan [Member]
Stock Option Plans [Line Items]
Maximum number of shares available				1,000,000
Shares available for grant				4,400,000
Performance-Based Restricted Stock [Member]
Stock Option Plans [Line Items]
Maximum number of shares granted during any fiscal year to any person				100,000
Cash Settled Performance Shares [Member] | Performance-Based Restricted Stock [Member]
Stock Option Plans [Line Items]
Maximum amount payable for the shares granted during any fiscal year to any person				$ 5,000,000
Stock Settled Performance Shares [Member] | Performance-Based Restricted Stock [Member]
Stock Option Plans [Line Items]
Maximum number of shares granted during any fiscal year to any person				100,000
Maximum [Member]
Stock Option Plans [Line Items]
Maximum period for the exercise of stock options, years				7 years
Minimum [Member]
Stock Option Plans [Line Items]
Minimum exercise price of stock options, percent of fair market value of a share of common stock on the date of grant				100.00%
Period of Service from Grant Date Stock Options Awarded Not Subject to Forfeiture				2 years	2 years	2 years	2 years
Minimum [Member] | Executive Officer [Member]
Stock Option Plans [Line Items]
Minimum age of employee with not subject to award forfeiture on condition compliance				55 years	55 years	55 years	55 years
Black-Scholes Option Pricing Model [Member]
Stock Option Plans [Line Items]
Weighted average fair value per option for all options				$ 8.45	$ 9.25	$ 9.66

Stock Option Plans - Black-Scho

Stock Option Plans - Black-Scholes Option Pricing Model with Weighted Average (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Expected dividend yield	3.00%	3.00%	3.00%
Expected risk-free interest rate	1.60%	1.80%	1.80%
Volatility	27.70%	28.20%	28.90%
Expected life (in years)	5 years 6 months	5 years 6 months	5 years 6 months

Stock Option Plans - Stock Opti

Stock Option Plans - Stock Option Activity and Related Information (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Shares Under Option, Beginning balance	8.8	8.4	8.3
Shares Under Option, Granted	2.6	1.9	1.9
Shares Under Option, Exercised	(1.1)	(1.4)	(1.6)
Shares Under Option, Forfeited or canceled		(0.1)	(0.2)
Shares Under Option, Ending balance	10.3	8.8	8.4
Shares Under Option, Exercisable at end of year	2.2	2.1	2.6
Shares Under Option, Ending vested and expected to vest	10.1	8.7	8.3
Weighted Average Exercise Price, Beginning balance	$ 39.25	$ 35.49	$ 31.35
Weighted Average Exercise Price, Granted	43.72	46.19	46.86
Weighted Average Exercise Price, Exercised	29.50	27.59	28.80
Weighted Average Exercise Price, Forfeited or canceled		27.59	28.36
Weighted Average Exercised Price, Ending balance	41.40	39.25	35.49
Weighted Average Exercise Price, Exercisable at end of year	32.37	28.54	26.91
Weighted Average Exercise price, Ending vested and expected to vest	$ 41.34	$ 39.15	$ 35.38
Weighted Average Remaining Contractual Term (in years), Ending balance	4 years 1 month 24 days	4 years 1 month 28 days	3 years 11 months 16 days
Weighted Average Remaining Contractual Term (in years), Exercisable at end of year	1 year 8 months 23 days	1 year 11 months 1 day	1 year 10 months 13 days
Weighted Average Remaining Contractual Term (in years), Ending vested and expected to vest	4 years 1 month 13 days	4 years 1 month 17 days	3 years 11 months 5 days
Aggregate Intrinsic Value, Ending Balance	$ 108.8	$ 36.7	$ 97.2
Aggregate Intrinsic Value, Exercisable at end of year	43.7	25.9	52.8
Aggregate Intrinsic Value, Ending vested and expected to vest	$ 107.5	$ 36.6	$ 96.6

Stock Option Plans - Stock Op75

Stock Option Plans - Stock Options Outstanding and Exercisable (Detail) - $ / shares shares in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, minimum	$ 23.76
Range of Exercise Prices, maximum	$ 49.55
Option Outstanding, Number Outstanding	10.3
Option Outstanding, Weighted Average Remaining Contractual Term (in years)	4 years 1 month 24 days	4 years 1 month 28 days	3 years 11 months 16 days
Option Outstanding, Weighted Average Exercise Price	$ 41.40	$ 39.25	$ 35.49	$ 31.35
Options Exercisable, Number Exercisable	2.2
Option Exercisable, Weighted Average Exercise Price	$ 32.37
Exercise Prices Range $ 23.76 - $ 35.71 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, minimum	23.76
Range of Exercise Prices, maximum	$ 35.71
Option Outstanding, Number Outstanding	2.3
Option Outstanding, Weighted Average Remaining Contractual Term (in years)	1 year 6 months 7 days
Option Outstanding, Weighted Average Exercise Price	$ 31.54
Options Exercisable, Number Exercisable	1.8
Option Exercisable, Weighted Average Exercise Price	$ 30.65
Exercise Prices Range $ 35.95 - $ 39.17 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, minimum	35.95
Range of Exercise Prices, maximum	$ 39.17
Option Outstanding, Number Outstanding	1.5
Option Outstanding, Weighted Average Remaining Contractual Term (in years)	3 years 2 months 12 days
Option Outstanding, Weighted Average Exercise Price	$ 39.15
Options Exercisable, Number Exercisable	0.4
Option Exercisable, Weighted Average Exercise Price	$ 39.12
Exercise Prices Range $ 43.71 - $ 43.71 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, minimum	43.71
Range of Exercise Prices, maximum	$ 43.71
Option Outstanding, Number Outstanding	2.6
Option Outstanding, Weighted Average Remaining Contractual Term (in years)	6 years 2 months 16 days
Option Outstanding, Weighted Average Exercise Price	$ 43.71
Exercise Prices Range $ 46.17 - $ 46.87 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, minimum	46.17
Range of Exercise Prices, maximum	$ 49.55
Option Outstanding, Number Outstanding	3.9
Option Outstanding, Weighted Average Remaining Contractual Term (in years)	4 years 8 months 12 days
Option Outstanding, Weighted Average Exercise Price	$ 46.53

Deferred Compensation - Additio

Deferred Compensation - Additional information (Detail) - USD ($) shares in Millions	3 Months Ended				12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014	Jun. 30, 2013	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Investments And Employee Deferred Compensation Plan [Line Items]
Deferred Equity Participation Plan, distributions to key executives, age					Age 62 (or the one-year anniversary of the date of the grant for participants over the age of 61 as of the grant date) or upon or after their actual retirement
Deferred Equity Participation Sub-plans, distributions to key executives, age					Age 65
Deferred Equity Participation Sub-plans, distributions requisite service description					we made awards under sub-plans of the DEPP for certain production staff, which generally provide for vesting and/or distributions no sooner than five years from the date of awards, although certain awards vest and/or distribute after earlier of fifteen years or the participant reaching age 65.
Deferred Equity Participation Plan (DEPP) [Member]
Investments And Employee Deferred Compensation Plan [Line Items]
Awards approved by committee, value	$ 10,100,000	$ 8,900,000	$ 9,200,000
Charge to compensation expenses related to awards					$ 7,500,000	$ 7,200,000	$ 7,400,000
Common stock purchased from open market, share				1.2
Common stock purchased from open market, value				$ 52,400,000
Cash and equity awards with aggregate fair value vested and distributed to participants					7,600,000	2,300,000	$ 18,800,000
Unearned deferred compensation, value					$ 46,800,000	$ 33,500,000
Unearned deferred compensation, shares					2.4	2.1
Total intrinsic value of unvested equity based awards					$ 125,500,000	$ 85,200,000
Deferred Cash Participation Plan (DCPP) [Member]
Investments And Employee Deferred Compensation Plan [Line Items]
Awards approved by committee, value	$ 3,100,000	$ 2,700,000
Charge to compensation expenses related to awards					1,500,000	1,100,000
Cash and equity awards with aggregate fair value vested and distributed to participants					0	$ 0
Deferred Equity Participation Plan Sub Plans [Member]
Investments And Employee Deferred Compensation Plan [Line Items]
Awards approved by committee, value					13,600,000
Charge to compensation expenses related to awards					1,300,000
Cash and equity awards with aggregate fair value vested and distributed to participants					$ 0

Restricted Stock, Performance77

Restricted Stock, Performance Share and Cash Awards - Additional Information (Detail)	Mar. 17, 2016USD ($)shares	Mar. 11, 2015USD ($)shares	Mar. 12, 2014USD ($)shares	Mar. 31, 2016shares	Sep. 30, 2014USD ($)shares	Dec. 31, 2016USD ($)Timesshares	Dec. 31, 2015USD ($)shares	Mar. 31, 2015shares	Dec. 31, 2014USD ($)shares	Mar. 31, 2014shares	Dec. 31, 2013shares	Mar. 13, 2013USD ($)shares	May 12, 2009shares
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Share-based compensation, shares outstanding | shares						10,300,000	8,800,000		8,400,000		8,300,000
Shares granted in the period | shares						479,167	394,975		376,541
Minimum [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Period of Service from Grant Date Stock Options Awarded Not Subject to Forfeiture						2 years	2 years		2 years		2 years
Executive Officer [Member] | Minimum [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Minimum age of employee with not subject to award forfeiture on condition compliance						55 years	55 years		55 years		55 years
Officer and Key Employees [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Stock options granted, exercise percentage, on the anniversary date of the grant in 2015	34.00%	34.00%	34.00%
Stock options granted, exercise percentage, on the anniversary date of the grant in 2016	33.00%	33.00%	33.00%
Stock options granted, exercise percentage, on the anniversary date of the grant in 2017	33.00%	33.00%	33.00%
Restricted Stock Units (RSUs) [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Share-based compensation, shares outstanding, Value						$ 2,000,000
Share-based compensation, shares outstanding | shares						1,000,000
Share based payment award vesting date				Mar. 17, 2021				Mar. 11, 2020		Mar. 12, 2018
Restricted stock or unit expense						$ 18,200,000	$ 14,400,000		$ 12,700,000
Restricted Stock Units (RSUs) [Member] | Minimum [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Period of Service from Grant Date Stock Options Awarded Not Subject to Forfeiture						2 years	2 years		2 years
Restricted Stock Units (RSUs) [Member] | Executive Officer [Member] | Minimum [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Minimum age of employee with not subject to award forfeiture on condition compliance						55 years	55 years		55 years
Restricted Stock Plan [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Shares authorized | shares													4,000,000
Shares granted in the period | shares				466,600	33,741	479,167	394,975	362,600	376,541	323,550
Fair value of grants in period					$ 1,500,000	$ 20,400,000	$ 16,700,000		$ 16,000,000
Stock options granted, exercise percentage, on the anniversary date of the grant in 2015						34.00%
Stock options granted, exercise percentage, on the anniversary date of the grant in 2016						33.00%
Stock options granted, exercise percentage, on the anniversary date of the grant in 2017						33.00%
Unvested Restricted Stock [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Total intrinsic value						$ 80,000,000	56,100,000
Equity awards with an aggregate fair value						14,200,000	10,200,000
Performance Shares [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Shares authorized | shares	72,900	53,900	48,850
Total intrinsic value						$ 8,900,000
Performance unit awards approved, Fair value	$ 3,200,000	$ 2,500,000	$ 2,300,000
Provisional awards, terms						Granted units for the 2016, 2015 and 2014 provisional awards will fully vest based on continuous employment through March 17, 2019, March 11, 2018 and March 12, 2017, respectively, and will be settled in shares of our common stock on a one-for-one basis as soon as practicable in 2019, 2018 and 2017, respectively.
Performance period, years						1 year
Vesting period, years						2 years
Compensation expense						$ 2,900,000
Cash Awards [Member] | Officer and Key Employees [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Provisional awards, terms						For certain of our executive officers age 55 or older, awards granted under the Program in 2016 are no longer subject to forfeiture upon such officers' departure from the company after two years from the date of the provisional award. The ultimate award value will be equal to the trailing twelve-month stock price on December 31, 2018, multiplied by the number of units subject to the award, but limited to between 0.5 and 1.5 times the original value of the units determined as of the grant date.
Performance period, years						1 year
Vesting period, years						2 years
Provisional compensation cash awards approved for future grant by compensation committee, value	$ 17,400,000	$ 14,600,000	$ 10,800,000			$ 11,200,000						$ 10,500,000
Provisional compensation cash award approved for future grant by compensation committee, units | shares	397,000	315,000	229,000	294,000		246,000		220,000		263,000		269,000
Ultimate award value, multiples of original value of the units, minimum | Times						0.5
Ultimate award value, multiples of original value of the units, maximum | Times						1.5
2016 Provisional Cash Awards [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Provisional compensation cash award approved for future grant by compensation committee, units | shares						385,000
Cash-based compensation awards, expenses						$ 0
2015 Provisional Cash Awards [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Cash-based compensation awards, expenses						6,600,000	0
2014 Provisional Cash Awards [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Cash-based compensation awards, expenses						4,500,000	4,900,000		0
2013 Provisional Cash Awards [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Cash-based compensation awards, expenses						$ 0	$ 5,300,000		$ 5,900,000
2012 Provisional Cash Awards [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Provisional compensation cash award approved for future grant by compensation committee, units | shares							342,000
Grants vested in period fair value							$ 15,800,000
2011 Provisional Cash Awards [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Provisional compensation cash award approved for future grant by compensation committee, units | shares									411,000
Grants vested in period fair value									$ 17,600,000

Restricted Stock, Performance78

Restricted Stock, Performance Share and Cash Awards - Schedule of Restricted Stock Awards Vesting Periods (Detail) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Vesting Period [Line Items]
Shares granted in the period	479,167	394,975	376,541
Vesting Period One Year [Member]
Vesting Period [Line Items]
Shares granted in the period	27,417	22,175	19,250
Vesting period, years	1 year
Vesting Period Three Years [Member]
Vesting Period [Line Items]
Shares granted in the period			33,741
Vesting period, years	3 years
Vesting Period Four Years [Member]
Vesting Period [Line Items]
Shares granted in the period		9,200	323,550
Vesting period, years	4 years
Vesting Period Five Years [Member]
Vesting Period [Line Items]
Shares granted in the period	451,750	363,600
Vesting period, years	5 years

Retirement Plans - Reconciliati

Retirement Plans - Reconciliation of Balances of Pension Benefit Obligation and Fair Value of Plan Assets (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Benefit obligation at beginning of year		$ 261.8	$ 272
Service cost		1.5	1.1	$ 0.7
Interest cost		10.8	10.8	12.7
Net actuarial loss (gain)		1.8	(10.4)
Benefits paid	$ (43.3)	(14.6)	(11.7)
Benefit obligation at end of year	272	261.3	261.8	272
Fair value of plan assets at beginning of year		207.5	217.2
Actual return on plan assets		14.9	2
Contributions by the company		0	0	0
Benefits paid	(43.3)	(14.6)	(11.7)
Fair value of plan assets at end of year	$ 217.2	207.8	207.5	$ 217.2
Funded status of the plan (underfunded)		(53.5)	(54.3)
Noncurrent liabilities - accrued benefit liability		(53.5)	(54.3)
Accumulated other comprehensive loss - net actuarial loss		67.9	71.8
Net amount included in retained earnings		$ 14.4	$ 17.5

Retirement Plans - Components o

Retirement Plans - Components of Net Periodic Pension Benefit Cost and Other Changes in Plan Assets and Obligations Recognized in Earnings and Other Comprehensive Earnings (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Service cost	$ 1.5	$ 1.1	$ 0.7
Interest cost on benefit obligation	10.8	10.8	12.7
Expected return on plan assets	(14.6)	(15.3)	(18.7)
Amortization of net loss	5.3	6.2	2.3
Settlement			12
Net periodic benefit cost	3	2.8	9
Net loss incurred	1.4	2.9	42.5
Settlement recognition			(12)
Amortization of net loss	(5.3)	(6.2)	(2.3)
Total recognized in other comprehensive loss	(3.9)	(3.3)	28.2
Total recognized in net periodic pension cost and other comprehensive loss	(0.9)	(0.5)	37.2
Amortization of net loss	$ 5.5	$ 5.9	$ 6

Retirement Plans - Weighted Ave

Retirement Plans - Weighted Average Assumptions of Pension Benefit Obligation and Net Periodic Pension Benefit Cost (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Discount rate, pension benefit obligation	4.00%	4.25%
Weighted average expected long-term rate of return on plan assets, pension benefit obligation	7.25%	7.25%
Discount rate, net periodic pension benefit cost	4.25%	4.00%	4.75%
Weighted average expected long-term rate of return on plan assets, net periodic pension benefit cost	7.25%	7.25%	7.50%

Retirement Plans - Schedule of

Retirement Plans - Schedule of Benefit Payments Expected to be Paid by Plan (Detail) $ in Millions	Dec. 31, 2016USD ($)
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
2,017	$ 11.8
2,018	12.3
2,019	12.9
2,020	13.4
2,021	14.1
Years 2022 to 2026	$ 77.5

Retirement Plans - Summary of P

Retirement Plans - Summary of Plan's Weighted Average Asset Allocations (Detail)	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Total weighted average asset	100.00%	100.00%
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total weighted average asset	61.00%	59.00%
Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total weighted average asset	33.00%	33.00%
Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Total weighted average asset	6.00%	8.00%

Retirement Plans - Additional I

Retirement Plans - Additional Information (Detail)	1 Months Ended	3 Months Ended	12 Months Ended
	Aug. 31, 2014Employees	Dec. 31, 2014USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Defined Benefit Plan Disclosure [Line Items]
Expected period of return on plan assets, years			10 years	10 years
Minimum contribution by employer			$ 0	$ 0	$ 0
Discretionary contributions by employer			0	0	0
Aggregate lump sum payout		$ 43,300,000	$ 14,600,000	11,700,000
Number of employees covered in the plan | Employees	2,500
Defined benefit plan, description			Eligible participants had from September 12, 2014 to November 30, 2014 to accept the offer, and the lump-sum payments were made in November and December of 2014, and the accelerated reduced annuity payments began as of December 1, 2014.
Defined benefit plan benefit obligation period increase (decrease)					(60,000,000)
Defined benefit plan obligation (improvement to pension underfunding)					17,000,000
Non-cash settlement charge, pretax		12,000,000
Fair value of plan assets		217,200,000	$ 207,800,000	207,500,000	217,200,000
Postretirement benefit obligation and unfunded status of plan		$ 272,000,000	261,300,000	261,800,000	272,000,000
Net periodic postretirement benefit cost			$ 3,000,000	2,800,000	9,000,000
Foreign Retirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of eligible compensation for matching contributions by employer			5.00%
Contribution expense to plan			$ 30,600,000	31,700,000	29,700,000
Matching contributions by employer, percentage			100.00%
Additional percentage of eligible compensation for matching contributions by employer			5.00%
Qualified Contributory Savings and Thrift 401(k) Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of eligible compensation for matching contributions by employer			5.00%
Contribution expense to plan			$ 48,700,000	42,500,000	38,000,000
Matching contributions by employer, percentage			100.00%
Matching contributions vesting schedule			5 years
Nonqualified Deferred Compensation Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of eligible compensation for matching contributions by employer			5.00%
Contribution expense to plan			$ 5,600,000	4,700,000	3,700,000
Fair value of plan assets			263,300,000	201,200,000
Retiree Health Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefit obligation and unfunded status of plan			2,700,000	2,700,000
Net periodic postretirement benefit cost			$ (300,000)	$ (300,000)	$ (500,000)

Retirement Plans - Summary of85

Retirement Plans - Summary of Plan's Assets Carried at Fair Value (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Total fair value	$ 207.8	$ 207.5	$ 217.2
Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value	108.1	106.8
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value	$ 99.7	$ 100.7	$ 101.1

Retirement Plans - Reconcilia86

Retirement Plans - Reconciliation of Beginning and Ending Balances for Level 3 Assets of Plan Measured at Fair Value (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	$ 207.5	$ 217.2
Fair value of plan assets at end of year	207.8	207.5
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	100.7	101.1
Settlements	(7.5)
Unrealized gains	6.5	(0.4)
Fair value of plan assets at end of year	$ 99.7	$ 100.7

Investments - Investments Repor

Investments - Investments Reported in Other Current and Non-Current Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Assets	$ 93.7	$ 83.6
Funding Commitments	3.4
Chem-Mod LLC [Member]
Schedule of Equity Method Investments [Line Items]
Assets	4	4
Chem-Mod International LLC [Member]
Schedule of Equity Method Investments [Line Items]
Assets	2	2
Clean-Coal Investments [Member] | Controlling Interest [Member] | Fourteen 2009 Era Clean Coal Plants [Member]
Schedule of Equity Method Investments [Line Items]
Assets	14.3	13.9
Clean-Coal Investments [Member] | Controlling Interest [Member] | Nineteen 2011 Era Clean Coal Plants [Member]
Schedule of Equity Method Investments [Line Items]
Assets	69	60.3
Funding Commitments	2.7
Clean-Coal Investments [Member] | Noncontrolling Interests [Member] | One 2011 Era Clean Coal Plants [Member]
Schedule of Equity Method Investments [Line Items]
Assets	0.7	0.8
Other Investments [Member]
Schedule of Equity Method Investments [Line Items]
Assets	3.7	$ 2.6
Funding Commitments	$ 0.7

Investments - Investments Rep88

Investments - Investments Reported in Other Current and Non-Current Assets (Parenthetical) (Detail) - Clean-Coal Investments [Member]	12 Months Ended
	Dec. 31, 2016EntityPlant	Dec. 31, 2015EntityPlant
Schedule of Equity Method Investments [Line Items]
Number of variable interest entities	1
Fourteen 2009 Era Clean Coal Plants [Member] | Controlling Interest [Member]
Schedule of Equity Method Investments [Line Items]
Number of coal plants | Plant	14	14
Number of variable interest entities	6	6
One 2011 Era Clean Coal Plants [Member] | Noncontrolling Interests [Member]
Schedule of Equity Method Investments [Line Items]
Number of coal plants | Plant	1	1
Number of variable interest entities	1	1
Nineteen 2011 Era Clean Coal Plants [Member] | Controlling Interest [Member]
Schedule of Equity Method Investments [Line Items]
Number of coal plants | Plant	19	19
Number of variable interest entities	17	17

Investments - Additional Inform

Investments - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Ownership interest held	50.00%
Chem-Mod Clean-Coal Venture [Member]
Schedule of Equity Method Investments [Line Items]
Total assets of variable interest entities	$ 11.1	$ 10.3
Total liabilities of variable interest entities	0.8	0.9
Total revenues of limited liability companies	63.5	72.1
Total expenses of limited liability companies	$ 2.4	$ 3
Chem-Mod Clean-Coal Venture - U.S. and Canadian Operations [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest held	46.50%
Chem-Mod International LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest held	31.50%
C-Quest Technology LLC and C-Quest Technologies International LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest held	12.00%
Option to acquire additional interest, percent	15.00%
Option to acquire additional interest, total price	$ 7.5
End date for acquiring additional interest	Aug. 1, 2017

Investments - Clean Coal Invest

Investments - Clean Coal Investments - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)EntityPlant
Schedule of Equity Method Investments [Line Items]
Number of clean coal production plants seeking and negotiating for long term production contract	3
Chem-Mod LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of clean coal production plants owned	34
Chem-Mod LLC [Member] | 2009 Era Plants [Member]
Schedule of Equity Method Investments [Line Items]
Number of clean coal production plants owned	14
Chem-Mod LLC [Member] | 2011 Era Plants [Member]
Schedule of Equity Method Investments [Line Items]
Number of clean coal production plants owned	20
Long Term Production Contracts [Member]
Schedule of Equity Method Investments [Line Items]
Number of clean coal production plants owned	31
Clean-Coal Investments [Member]
Schedule of Equity Method Investments [Line Items]
Number of variable interest entities | Entity	1
Clean-Coal Investments [Member] | VIE [Member]
Schedule of Equity Method Investments [Line Items]
Total assets of limited liability companies | $	$ 15.7
Total liability of limited liability companies | $	13.4
Total revenues of limited liability companies | $	57.4
Total expenses of limited liability companies | $	$ 71.1

Investments - Other Investments

Investments - Other Investments - Additional Information (Detail)	Dec. 31, 2016USD ($)InvestmentVenture	Dec. 31, 2015USD ($)
Schedule of Equity Method Investments [Line Items]
Assets	$ 93,700,000	$ 83,600,000
Non controlling interest certified low-income housing developments | Investment	12
Non controlling interest in real estate entities | Investment	2
Carrying value of investments in real estate entities	$ 0
Other Investments [Member]
Schedule of Equity Method Investments [Line Items]
Assets	3,700,000	$ 2,600,000
Other Investments [Member] | Four Venture Capital Funds [Member]
Schedule of Equity Method Investments [Line Items]
Assets	$ 3,700,000
Non controlling interest in venture capital funds number | Venture	4
Other Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Schedule of Equity Method Investments [Line Items]
Assets	$ 60,000,000
Liabilities	20,000,000
Other Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] | Twelve Certified Low-Income Housing Developments [Member]
Schedule of Equity Method Investments [Line Items]
Carrying value of investments	$ 0

Derivatives and Hedging Activ92

Derivatives and Hedging Activity - Summary of Notional and Fair Values of Derivative Instruments (Detail) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Notional Amount	$ 204,100,000	$ 93,700,000
Derivatives Assets	13,500,000
Derivative Liabilities	17,500,000	1,700,000
Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	200,000,000
Derivatives Assets	11,400,000
Foreign Exchange Contracts [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	4,100,000	93,700,000
Derivatives Assets	2,100,000
Derivative Liabilities	$ 17,500,000	$ 1,700,000

Derivatives and Hedging Activ93

Derivatives and Hedging Activity - Summary of Notional and Fair Values of Derivative Instruments (Parenthetical) (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Derivative assets - current	$ 12.5	$ 0
Derivative assets - non current	1	0
Derivative liabilities - current	11.8	1.7
Derivative liabilities - non current	5.7	0
Foreign Exchange Contracts [Member] | Call Options [Member]
Derivatives, Fair Value [Line Items]
Foreign exchange derivative contracts	78.3
Foreign Exchange Contracts [Member] | Put Options [Member]
Derivatives, Fair Value [Line Items]
Foreign exchange derivative contracts	78.3
Foreign Exchange Contracts [Member] | Forward Contracts [Member]
Derivatives, Fair Value [Line Items]
Foreign exchange derivative contracts	$ 61.6	43.9
Foreign Exchange Contracts [Member] | Forward Contracts [Member] | Call Options [Member]
Derivatives, Fair Value [Line Items]
Foreign exchange derivative contracts		57.5
Foreign Exchange Contracts [Member] | Forward Contracts [Member] | Put Options [Member]
Derivatives, Fair Value [Line Items]
Foreign exchange derivative contracts		$ 137.6

Derivatives and Hedging Activ94

Derivatives and Hedging Activity - Summary of Amounts of Derivative Gains (Losses) Recognized In Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses) recognized in accumulated other comprehensive loss	$ (11.5)	$ (2.8)	$ (2.2)
Derivative gains (losses) reclassified from accumulated other comprehensive loss into income (effective portion)	(8.2)	0.7	(0.5)
Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses) recognized in accumulated other comprehensive loss	12.4
Derivative gains (losses) reclassified from accumulated other comprehensive loss into income (effective portion)	0.1
Foreign Exchange Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses) recognized in accumulated other comprehensive loss	(23.9)	(2.8)	(2.2)
Derivative gains (losses) reclassified from accumulated other comprehensive loss into income (effective portion)	(8.3)	0.7	(0.5)
Commission Revenue [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses) recognized in accumulated other comprehensive loss	(24)	(3.3)	(2.5)
Derivative gains (losses) reclassified from accumulated other comprehensive loss into income (effective portion)	(9.1)	0.7	0.9
Commission Revenue [Member] | Foreign Exchange Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses) recognized in accumulated other comprehensive loss	(24)	(3.3)	(2.5)
Derivative gains (losses) reclassified from accumulated other comprehensive loss into income (effective portion)	(9.1)	0.7	0.9
Compensation Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses) recognized in accumulated other comprehensive loss	0.1	0.3	0.2
Derivative gains (losses) reclassified from accumulated other comprehensive loss into income (effective portion)	0.5		(0.7)
Compensation Expense [Member] | Foreign Exchange Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses) recognized in accumulated other comprehensive loss	0.1	0.3	0.2
Derivative gains (losses) reclassified from accumulated other comprehensive loss into income (effective portion)	0.5		(0.7)
Operating Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses) recognized in accumulated other comprehensive loss		0.2	0.1
Derivative gains (losses) reclassified from accumulated other comprehensive loss into income (effective portion)	0.3		(0.7)
Operating Expense [Member] | Foreign Exchange Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses) recognized in accumulated other comprehensive loss		$ 0.2	0.1
Derivative gains (losses) reclassified from accumulated other comprehensive loss into income (effective portion)	0.3		$ (0.7)
Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses) recognized in accumulated other comprehensive loss	12.4
Derivative gains (losses) reclassified from accumulated other comprehensive loss into income (effective portion)	0.1
Interest Expense [Member] | Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses) recognized in accumulated other comprehensive loss	12.4
Derivative gains (losses) reclassified from accumulated other comprehensive loss into income (effective portion)	$ 0.1

Derivatives and Hedging Activ95

Derivatives and Hedging Activity - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net [Abstract]
Pretax losses currently included within Accumulated other comprehensive loss to be reclassified into earnings	$ 0.4
Gain (loss) related to hedge ineffectiveness	$ 1.6	$ 0.7	$ 0

Commitments, Contingencies an96

Commitments, Contingencies and Off-Balance Sheet Arrangements - Contractual Obligations (Detail) $ in Millions	Dec. 31, 2016USD ($)
Note Purchase Agreements [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2017	$ 300
Contractual Obligations, Payments Due by Period, 2018	100
Contractual Obligations, Payments Due by Period, 2019	100
Contractual Obligations, Payments Due by Period, 2020	100
Contractual Obligations, Payments Due by Period, 2021	75
Contractual Obligations, Payments Due by Period, Thereafter	1,775
Contractual Obligations, Payments Due by Period, Total	2,450
Multi Currency Credit Agreement [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2017	278
Contractual Obligations, Payments Due by Period, Total	278
Premium Financing Debt Facility [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2017	125.6
Contractual Obligations, Payments Due by Period, Total	125.6
Interest On Debt [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2017	113.5
Contractual Obligations, Payments Due by Period, 2018	93.3
Contractual Obligations, Payments Due by Period, 2019	89
Contractual Obligations, Payments Due by Period, 2020	84.4
Contractual Obligations, Payments Due by Period, 2021	79.5
Contractual Obligations, Payments Due by Period, Thereafter	280.5
Contractual Obligations, Payments Due by Period, Total	740.2
Total Debt Obligations [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2017	817.1
Contractual Obligations, Payments Due by Period, 2018	193.3
Contractual Obligations, Payments Due by Period, 2019	189
Contractual Obligations, Payments Due by Period, 2020	184.4
Contractual Obligations, Payments Due by Period, 2021	154.5
Contractual Obligations, Payments Due by Period, Thereafter	2,055.5
Contractual Obligations, Payments Due by Period, Total	3,593.8
Operating Lease Obligations [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2017	101.1
Contractual Obligations, Payments Due by Period, 2018	83.8
Contractual Obligations, Payments Due by Period, 2019	68.4
Contractual Obligations, Payments Due by Period, 2020	56.4
Contractual Obligations, Payments Due by Period, 2021	45.8
Contractual Obligations, Payments Due by Period, Thereafter	112.9
Contractual Obligations, Payments Due by Period, Total	468.4
Less Sublease Arrangements [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2017	(0.8)
Contractual Obligations, Payments Due by Period, 2018	(0.4)
Contractual Obligations, Payments Due by Period, 2019	(0.1)
Contractual Obligations, Payments Due by Period, 2020	(0.1)
Contractual Obligations, Payments Due by Period, Thereafter	(0.1)
Contractual Obligations, Payments Due by Period, Total	(1.5)
Outstanding Purchase Obligations [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2017	50.6
Contractual Obligations, Payments Due by Period, 2018	32.1
Contractual Obligations, Payments Due by Period, 2019	16.6
Contractual Obligations, Payments Due by Period, 2020	7.7
Contractual Obligations, Payments Due by Period, 2021	1.7
Contractual Obligations, Payments Due by Period, Total	108.7
Total Contractual Obligations [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2017	968
Contractual Obligations, Payments Due by Period, 2018	308.8
Contractual Obligations, Payments Due by Period, 2019	273.9
Contractual Obligations, Payments Due by Period, 2020	248.4
Contractual Obligations, Payments Due by Period, 2021	202
Contractual Obligations, Payments Due by Period, Thereafter	2,168.3
Contractual Obligations, Payments Due by Period, Total	$ 4,169.4

Commitments, Contingencies an97

Commitments, Contingencies and Off-Balance Sheet Arrangements - Additional Information (Detail)	12 Months Ended			180 Months Ended
	Dec. 31, 2016USD ($)ft²EntityEmployeesLetterOfCredit	Dec. 31, 2015USD ($)Entity	Dec. 31, 2014USD ($)Entity	Dec. 31, 2016USD ($)ft²Entity
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Acquired property through lease area, sqft | ft²	306,000
Acquired property through lease percentage of building	60.00%
Operating lease commitment, expiration date	Feb. 28, 2018
Number of square feet | ft²	360,000			360,000
Number of employees will accommodate at new facility | Employees	2,000
Total rent expense	$ 134,200,000	$ 121,600,000	$ 122,000,000
Number of companies acquired | Entity	101	105	67	420
Aggregate amount of maximum earnout obligations related to acquisitions	$ 527,200,000	$ 565,400,000
Aggregate amount of maximum earnout obligations related to acquisitions, recorded in consolidated balance sheet	$ 242,300,000	$ 229,700,000
Ownership interest	50.00%			50.00%
Liabilities recorded on self-insurance	$ 12,300,000			$ 12,300,000
Debt	$ 26,900,000			26,900,000
Self-Insurance Deductibles [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Number of letters of credit issued | LetterOfCredit	2
Rent-A-Captive Facility [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Number of letters of credit issued | LetterOfCredit	7
Letter of Credit [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Debt	$ 5,000,000			5,000,000
Number of letters of credit issued | LetterOfCredit	1
Letter of Credit [Member] | Security Deposit [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Debt	$ 500,000			500,000
Number of letters of credit issued | LetterOfCredit	1
Letter of Credit [Member] | Self-Insurance Deductibles [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Liabilities recorded on self-insurance	$ 9,300,000			9,300,000
Debt	12,300,000			12,300,000
Letter of Credit [Member] | Rent-A-Captive Facility [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Debt	$ 6,300,000			$ 6,300,000
Tax Increment Financing [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Property tax credit expect to receive period	15 years
Minimum [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Ownership interest	1.00%			1.00%
Minimum [Member] | Tax Increment Financing [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Property tax credit expect to receive	$ 60,000,000			$ 60,000,000
Maximum [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Ownership interest	50.00%			50.00%
Maximum [Member] | Tax Increment Financing [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Property tax credit expect to receive	$ 80,000,000			$ 80,000,000
Outstanding Purchase Obligations Related to New Corporate Headquarters Building [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, Total	$ 10,600,000			$ 10,600,000

Commitments, Contingencies an98

Commitments, Contingencies and Off-Balance Sheet Arrangements - Off-Balance Sheet Commitments (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Amount of Commitment Expiration by Period - 2017	$ 2.9
Amount of Commitment Expiration by Period - 2018	0.2
Amount of Commitment Expiration by Period - 2019	0.2
Amount of Commitment Expiration by Period - 2020	0.2
Amount of Commitment Expiration by Period - 2021	0.2
Amount of Commitment Expiration by Period - Thereafter	23.2
Total Amounts Committed	26.9
Letters of Credit [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Amount of Commitment Expiration by Period - Thereafter	21.1
Total Amounts Committed	21.1
Financial Guarantees [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Amount of Commitment Expiration by Period - 2017	0.2
Amount of Commitment Expiration by Period - 2018	0.2
Amount of Commitment Expiration by Period - 2019	0.2
Amount of Commitment Expiration by Period - 2020	0.2
Amount of Commitment Expiration by Period - 2021	0.2
Amount of Commitment Expiration by Period - Thereafter	1.4
Total Amounts Committed	2.4
Funding Commitments [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Amount of Commitment Expiration by Period - 2017	2.7
Amount of Commitment Expiration by Period - Thereafter	0.7
Total Amounts Committed	$ 3.4

Commitments, Contingencies an99

Commitments, Contingencies and Off-Balance Sheet Arrangements - Outstanding Letters of Credit, Financial Guarantees and Funding Commitments (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Maximum Exposure	$ 26.9
Liability Recorded	$ 12.3
Funding Commitment to One Fund Expires in 2023 Trigger [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Collateral	None
Compensation to Us	None
Maximum Exposure	$ 0.7
Credit Support Under Letters of Credit for Deductibles Due by Us on our Own Insurance Coverage's Expires after 2021 Trigger [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Collateral	None
Compensation to Us	None
Maximum Exposure	$ 9.3
Liability Recorded	$ 12.3
Credit Enhancement Under Letters of Credit for our Captive Insurance Operations to Meet Minimum Statutory Capital Requirements Expires after 2021 [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Collateral	None
Compensation to Us	Reimbursement of LOC fees
Maximum Exposure	$ 6.3
Credit Support Under Letters of Credit for Clients Claim Funds Held by Our Bermuda Captive Insurance Operation in Fiduciary Capacity Expires After 2021 [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Collateral	None
Compensation to Us	Reimbursement of LOC fees
Maximum Exposure	$ 5
Funding Commitments on Clean Energy Investment [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Collateral	None
Compensation to Us	None
Maximum Exposure	$ 2.7
Credit Support Under Letters of Credit in Lieu of Security Deposit for Acquisition Lease Expires 2023 [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Collateral	None
Compensation to Us	None
Maximum Exposure	$ 0.5
Financial Guarantees of Loans to Nineteen Canadian Based Employees Trigger [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Collateral	(1)
Compensation to Us	None
Maximum Exposure	$ 2.4

Commitments, Contingencies a100

Commitments, Contingencies and Off-Balance Sheet Arrangements - Litigation, Regulatory and Taxation Matters- Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016Companies
Minimum [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Number of micro-captive insurance companies organized or managed	100

Commitments, Contingencies a101

Commitments, Contingencies and Off-Balance Sheet Arrangements - Contingent Liabilities - Additional Information (Detail) - Errors and Omissions [Member]	12 Months Ended
	Dec. 31, 2016USD ($)
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Insurance claims, amount retained	$ 5,000,000
Amount of losses in excess of retained amounts	175,000,000
Maximum [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Actuarial range value	7,600,000
Minimum [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Actuarial range value	$ 1,700,000

Commitments, Contingencies a102

Commitments, Contingencies and Off-Balance Sheet Arrangements - Tax - advantaged Investments No Longer Held - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)
Commitments and Contingencies Disclosure [Abstract]
Income tax credits and adjustments	$ 109

Insurance Operations - Summary

Insurance Operations - Summary of Reconciliations of Direct to Net premiums on Written and Earned Basis Related to Wholly Owned Insurance Company Subsidiary (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Premiums Written and Earned [Abstract]
Written, Direct	$ 71.8	$ 71.5	$ 34.9
Written, Assumed	5.2	4.4	2.3
Written, Ceded	(77)	(75.9)	(37.2)
Written, Net	0	0	0
Earned, Direct	69.6	71.7	2.4
Earned, Assumed	4.9	5.1	0.2
Earned, Ceded	(74.5)	(76.8)	(2.6)
Earned, Net	$ 0	$ 0	$ 0

Insurance Operations - Addition

Insurance Operations - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Insurance [Abstract]
Reinsurance recoverables amount	$ 48.3	$ 40.1

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Expense Benefit [Line Items]
Earnings (losses) before income taxes, foreign	$ 5.6	$ (52.1)	$ 3.4
Interest expense, foreign deposits	110.7	107	76.5
Interest expense, domestic deposits	110.7	107	$ 76.5
Net unrecognized tax benefits	10	10.8
Accrued interest and penalties related to unrecognized tax benefits	2.8	1.1
Deferred tax liabilities	371.1	352.1
Deferred minimum tax credits	108.2
Deferred business tax credits	$ 368.8
Deferred business tax credits expiration year	2,033
Deferred state tax credits	$ 0.9
Deferred state tax credits expiration year	2,021
Undistributed earnings of foreign subsidiaries	$ 243	231.9
Unrecognized deferred tax liability on undistributed earnings	15.6	10.4
Noncurrent Liabilities [Member]
Income Tax Expense Benefit [Line Items]
Deferred tax liabilities	$ 371.1	$ 352.1

Income Taxes - Components of Ea

Income Taxes - Components of Earnings Before Income Taxes and Provision for Income Taxes (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
United States									$ 351.3	$ 345.6	$ 288.1
Foreign, principally Australia, Canada, New Zealand and the U.K.									5.6	(52.1)	3.4
Earnings before income taxes	$ 68.8	$ 94.9	$ 137.5	$ 55.7	$ 28.4	$ 105.7	$ 128.5	$ 30.9	356.9	293.5	291.5
Federal Current									45.9	43.9	38.8
Federal Deferred									(146.7)	(139.4)	(96.6)
Total Provision (benefit) for income taxes, Federal									(100.8)	(95.5)	(57.8)
State and local Current									8.4	18.9	19.5
State and local Deferred									(0.3)	(3.3)	(1.1)
Total Provision (benefit) for income taxes, State and local									8.1	15.6	18.4
Foreign Current									22.4	22.9	30.5
Foreign Deferred									(17.8)	(38.6)	(27.1)
Total Provision (benefit) for income taxes, Foreign									4.6	(15.7)	3.4
Benefit for income taxes									$ (88.1)	$ (95.6)	$ (36)

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Provision for Income Taxes with Federal Statutory Income Tax Rate (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Federal statutory rate	$ 124.9	$ 102.7	$ 102
State income taxes - net of Federal benefit	5.3	10.2	12
Differences related to non U.S. operations	(34.1)	(22.6)	(11.2)
Alternative energy, foreign and other tax credits	(194.4)	(181.3)	(145.5)
Other permanent differences	(4.8)	(4.9)	(2.5)
Nondeductible employee compensation			5.4
Changes in unrecognized tax benefits	2.2	3	2.4
Change in valuation allowance	14	1.7
Change in U.K. tax rate	(1.5)	(4.2)
Other	0.3	(0.2)	1.4
Benefit for income taxes	$ (88.1)	$ (95.6)	$ (36)
Federal statutory rate, % of Pretax Earnings	35.00%	35.00%	35.00%
State income taxes-net of Federal benefit, % of Pretax Earnings	1.50%	3.50%	4.10%
Differences related to non U.S. operations, % of Pretax Earnings	(9.60%)	(7.70%)	(3.80%)
Alternative energy, foreign and other tax credits, % of Pretax Earnings	(54.50%)	(61.80%)	(49.90%)
Other permanent differences, % of Pretax Earnings	(1.30%)	(1.70%)	(0.90%)
Nondeductible employee compensation, % of Pretax Earnings			1.90%
Changes in unrecognized tax benefits, % of Pretax Earnings	0.60%	1.00%	0.80%
Change in valuation allowance, % of Pretax Earnings	3.90%	0.60%
Change in U.K. tax rate, % of Pretax Earnings	(0.40%)	(1.40%)
Other, % of Pretax Earnings	0.10%	(0.10%)	0.50%
Total benefit for income taxes-continuing operations, % of Pretax Earnings	(24.70%)	(32.60%)	(12.30%)

Income Taxes - Gross Unrecogniz

Income Taxes - Gross Unrecognized Tax Benefit (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Gross unrecognized tax benefits at January	$ 15.7	$ 12.5
Increases in tax positions for current year	2.4	2.9
Settlements	(1.4)
Lapse in statute of limitations	(1.8)	(1.3)
Increases in tax positions for prior years	1.8	2.1
Decreases in tax positions for prior years	(2.2)	(0.5)
Gross unrecognized tax benefits at December	$ 14.5	$ 15.7

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Alternative minimum tax and other credit carryforwards	$ 477.9	$ 341.6
Accrued and unfunded compensation and employee benefits	219	197
Amortizable intangible assets	38.8	39.4
Compensation expense related to stock options	16.9	12.6
Accrued liabilities	31.7	34.3
Accrued pension liability	22.9	23.4
Investments	7.7	9.5
Net operating loss carryforwards	20.4	19.2
Capital loss carryforwards	16	2.9
Deferred rent liability	8.1	8.7
Other	3.9	7.7
Total deferred tax assets	863.3	696.3
Valuation allowance for deferred tax assets	(66.8)	(52.8)
Deferred tax assets	796.5	643.5
Nondeductible amortizable intangible assets	310.2	307.1
Investment-related partnerships	34.5	28.7
Depreciable fixed assets	18.2	11.7
Hedging instruments	4.1
Other prepaid items	4.1	4.6
Total deferred tax liabilities	371.1	352.1
Net deferred tax assets	$ 425.4	$ 291.4

Accumulated Other Comprehens110

Accumulated Other Comprehensive Earnings - Schedule of Accumulated Other Comprehensive Earnings (Loss) Attributable to Controlling Interests (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (522.5)
Ending Balance	(763.6)	$ (522.5)
Pension Liability [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(42.9)	(44.2)	$ (25.6)
Net change in period	(4.4)	1.3	(18.6)
Ending Balance	(47.3)	(42.9)	(44.2)
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(477.4)	(216.3)	22.1
Net change in period	(231.8)	(261.1)	(238.4)
Ending Balance	(709.2)	(477.4)	(216.3)
Fair Value of Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(2.2)	(0.1)	0.9
Net change in period	(4.9)	(2.1)	(1)
Ending Balance	(7.1)	(2.2)	(0.1)
Accumulated Other Comprehensive Earnings (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(522.5)	(260.6)	(2.6)
Net change in period	(241.1)	(261.9)	(258)
Ending Balance	$ (763.6)	$ (522.5)	$ (260.6)

Accumulated Other Comprehens111

Accumulated Other Comprehensive Earnings - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Expense related to pension liability reclassified from accumulated other comprehensive earnings	$ 5,300,000	$ 6,200,000	$ 14,300,000
Income (expense) related to fair value of derivative investments reclassified from accumulated other comprehensive earnings	(8,200,000)	700,000	(500,000)
Foreign currency translation reclassified from accumulated other comprehensive earnings	$ 0	$ 0	$ 0

Quarterly Operating Results 112

Quarterly Operating Results (unaudited) - Quarterly Operating Results (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Total revenues	$ 1,385	$ 1,482.3	$ 1,427.1	$ 1,300.4	$ 1,334.9	$ 1,454.8	$ 1,371.4	$ 1,231.3	$ 5,594.8	$ 5,392.4	$ 4,626.5
Total expenses	1,316.2	1,387.4	1,289.6	1,244.7	1,306.5	1,349.1	1,242.9	1,200.4
Earnings before income taxes	68.8	94.9	137.5	55.7	28.4	105.7	128.5	30.9	356.9	293.5	291.5
Net earnings attributable to controlling interests	$ 95.1	$ 122.8	$ 150	$ 46.5	$ 62.3	$ 133.3	$ 139.3	$ 21.9	$ 414.4	$ 356.8	$ 303.4
Basic net earnings per share	$ 0.53	$ 0.69	$ 0.85	$ 0.26	$ 0.35	$ 0.76	$ 0.82	$ 0.13
Diluted net earnings per share	$ 0.53	$ 0.69	$ 0.84	$ 0.26	$ 0.35	$ 0.75	$ 0.81	$ 0.13

Segment Information - Additiona

Segment Information - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016Segment
Segment Reporting [Abstract]
Number of reportable operating segments	3

Segment Information - Schedule

Segment Information - Schedule of Segment Reporting Information by Segment (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Commissions									$ 2,439.1	$ 2,338.7	$ 2,083
Fees									1,492.8	1,432.3	1,258.3
Supplemental commissions									147	125.5	104
Contingent commissions									107.2	93.7	84.7
Investment income									53.3	54.2	41.3
Gains on books of business sales and other									6.6	6.7	7.3
Revenue from clean coal activities									1,350.1	1,310.8	1,029.5
Other - net gain									(1.3)	30.5	18.4
Total revenues	$ 1,385	$ 1,482.3	$ 1,427.1	$ 1,300.4	$ 1,334.9	$ 1,454.8	$ 1,371.4	$ 1,231.3	5,594.8	5,392.4	4,626.5
Compensation									2,538.9	2,428.9	2,167.6
Operating									797.7	840.7	743.1
Cost of revenues from clean coal activities									1,408.6	1,351.5	1,058.9
Interest									109.8	103	89
Depreciation									103.6	93.9	69.4
Amortization									247.2	240.3	189.5
Change in estimated acquisition earnout payables									32.1	40.6	17.5
Total expenses									5,237.9	5,098.9	4,335
Earnings (loss) before income taxes									356.9	293.5	291.5
Provision (benefit) for income taxes									(88.1)	(95.6)	(36)
Net earnings									445	389.1	327.5
Net earnings attributable to noncontrolling interests									30.6	32.3	24.1
Net earnings (loss) attributable to controlling interests	95.1	122.8	150	46.5	62.3	133.3	139.3	21.9	414.4	356.8	303.4
Net foreign exchange gain (loss)									3	0.2	0.5
Total revenues	1,385	$ 1,482.3	$ 1,427.1	$ 1,300.4	1,334.9	$ 1,454.8	$ 1,371.4	$ 1,231.3	5,594.8	5,392.4	4,626.5
Total assets	11,489.6				10,910.5				11,489.6	10,910.5	10,010
Goodwill - net	3,767.8				3,662.9				3,767.8	3,662.9	3,449.6
Amortizable intangible assets - net	1,627.3				1,698.8				1,627.3	1,698.8	1,776
Brokerage [Member]
Segment Reporting Information [Line Items]
Goodwill - net	3,736.9				3,635.6				3,736.9	3,635.6	3,427.5
Corporate [Member]
Segment Reporting Information [Line Items]
Goodwill - net	2.8								2.8
Unites States [Member]
Segment Reporting Information [Line Items]
Total revenues									4,272.6	4,041.4	3,442.8
Total revenues									4,272.6	4,041.4	3,442.8
Total assets	6,556.3				5,882.9				6,556.3	5,882.9	5,046.6
Goodwill - net	2,138.5				1,970.4				2,138.5	1,970.4
Unites States [Member] | Brokerage [Member]
Segment Reporting Information [Line Items]
Goodwill - net	2,115				1,946.9				2,115	1,946.9
United Kingdom [Member]
Segment Reporting Information [Line Items]
Total revenues									712.1	766.9	726.2
Total revenues									712.1	766.9	726.2
Total assets	2,383.7				2,652.1				2,383.7	2,652.1	2,450.4
Goodwill - net	666.5				782.8				666.5	782.8
United Kingdom [Member] | Brokerage [Member]
Segment Reporting Information [Line Items]
Goodwill - net	662.2				779.3				662.2	779.3
Australia [Member]
Segment Reporting Information [Line Items]
Total revenues									245.5	256.7	236.6
Total revenues									245.5	256.7	236.6
Total assets	951.3				951.4				951.3	951.4	1,031.2
Goodwill - net	382.7				380.1				382.7	380.1
Australia [Member] | Brokerage [Member]
Segment Reporting Information [Line Items]
Goodwill - net	382.7				380.1				382.7	380.1
Canada [Member]
Segment Reporting Information [Line Items]
Total revenues									138.2	136.6	85
Total revenues									138.2	136.6	85
Total assets	576.1				578.1				576.1	578.1	642
Goodwill - net	292.2				282.6				292.2	282.6
Canada [Member] | Brokerage [Member]
Segment Reporting Information [Line Items]
Goodwill - net	292.2				282.6				292.2	282.6
New Zealand [Member]
Segment Reporting Information [Line Items]
Total revenues									125.8	122.6	81.3
Total revenues									125.8	122.6	81.3
Total assets	673.3				627.2				673.3	627.2	615.7
Goodwill - net	205.3				204.5				205.3	204.5
New Zealand [Member] | Brokerage [Member]
Segment Reporting Information [Line Items]
Goodwill - net	205				204.2				205	204.2
Other Foreign [Member]
Segment Reporting Information [Line Items]
Total revenues									100.6	68.2	54.6
Total revenues									100.6	68.2	54.6
Total assets	348.9				222.1				348.9	222.1	224.1
Goodwill - net	82.6				42.5				82.6	42.5
Other Foreign [Member] | Brokerage [Member]
Segment Reporting Information [Line Items]
Goodwill - net	79.8				42.5				79.8	42.5
Other Foreign [Member] | Corporate [Member]
Segment Reporting Information [Line Items]
Goodwill - net	2.8								2.8
Operating Segments [Member] | Brokerage [Member]
Segment Reporting Information [Line Items]
Commissions									2,439.1	2,338.7	2,083
Fees									775.7	705.8	577
Supplemental commissions									147	125.5	104
Contingent commissions									107.2	93.7	84.7
Investment income									52.3	53.6	40.3
Gains on books of business sales and other									6.6	6.7	7.3
Total revenues									3,527.9	3,324	2,896.3
Compensation									2,041.8	1,939.7	1,703.1
Operating									600.9	638.1	530.1
Depreciation									57.2	54.4	44.4
Amortization									244.7	237.3	186.3
Change in estimated acquisition earnout payables									32.1	41.1	17.6
Total expenses									2,976.7	2,910.6	2,481.5
Earnings (loss) before income taxes									551.2	413.4	414.8
Provision (benefit) for income taxes									194.1	145.3	151
Net earnings									357.1	268.1	263.8
Net earnings attributable to noncontrolling interests									3.6	1.7	0.9
Net earnings (loss) attributable to controlling interests									353.5	266.4	262.9
Net foreign exchange gain (loss)									2.9	(0.2)	1.1
Total revenues									3,527.9	3,324	2,896.3
Total assets	9,183.4				8,969.7				9,183.4	8,969.7	8,386.2
Goodwill - net	3,736.9				3,635.6				3,736.9	3,635.6	3,427.5
Amortizable intangible assets - net	1,613.6				1,677.8				1,613.6	1,677.8	1,757.3
Operating Segments [Member] | Risk Management [Member]
Segment Reporting Information [Line Items]
Fees									717.1	726.5	681.3
Investment income									1	0.6	1
Total revenues									718.1	727.1	682.3
Compensation									424.5	427.2	414.2
Operating									171.4	180.8	176.4
Depreciation									27.2	24.3	21.2
Amortization									2.5	3	3.2
Change in estimated acquisition earnout payables										(0.5)	(0.1)
Total expenses									625.6	634.8	614.9
Earnings (loss) before income taxes									92.5	92.3	67.4
Provision (benefit) for income taxes									35.3	35.1	25.3
Net earnings									57.2	57.2	42.1
Net earnings (loss) attributable to controlling interests									57.2	57.2	42.1
Total revenues									718.1	727.1	682.3
Total assets	666.4				660.1				666.4	660.1	574.9
Goodwill - net	28.1				27.3				28.1	27.3	22.1
Amortizable intangible assets - net	13.7				21				13.7	21	18.7
Operating Segments [Member] | Corporate [Member]
Segment Reporting Information [Line Items]
Revenue from clean coal activities									1,350.1	1,310.8	1,029.5
Other - net gain									(1.3)	30.5	18.4
Total revenues									1,348.8	1,341.3	1,047.9
Compensation									72.6	62	50.3
Operating									25.4	21.8	36.6
Cost of revenues from clean coal activities									1,408.6	1,351.5	1,058.9
Interest									109.8	103	89
Depreciation									19.2	15.2	3.8
Total expenses									1,635.6	1,553.5	1,238.6
Earnings (loss) before income taxes									(286.8)	(212.2)	(190.7)
Provision (benefit) for income taxes									(317.5)	(276)	(212.3)
Net earnings									30.7	63.8	21.6
Net earnings attributable to noncontrolling interests									27	30.6	23.2
Net earnings (loss) attributable to controlling interests									3.7	33.2	(1.6)
Net foreign exchange gain (loss)									0.1	0.4	(0.6)
Total revenues									1,348.8	1,341.3	1,047.9
Total assets	1,639.8				1,284				1,639.8	1,284	1,048.9
Goodwill - net	2.8								2.8
Operating Segments [Member] | Unites States [Member] | Brokerage [Member]
Segment Reporting Information [Line Items]
Total revenues									2,334.4	2,122.1	1,873.3
Total revenues									2,334.4	2,122.1	1,873.3
Total assets	4,393.6				4,092.8				4,393.6	4,092.8	3,557.1
Operating Segments [Member] | Unites States [Member] | Risk Management [Member]
Segment Reporting Information [Line Items]
Total revenues									610.3	591.8	532.6
Total revenues									610.3	591.8	532.6
Total assets	540.5				525.2				540.5	525.2	457.5
Operating Segments [Member] | Unites States [Member] | Corporate [Member]
Segment Reporting Information [Line Items]
Total revenues									1,327.9	1,327.5	1,036.9
Total revenues									1,327.9	1,327.5	1,036.9
Total assets	1,622.2				1,264.9				1,622.2	1,264.9	1,032
Operating Segments [Member] | United Kingdom [Member] | Brokerage [Member]
Segment Reporting Information [Line Items]
Total revenues									686.5	738.5	696.8
Total revenues									686.5	738.5	696.8
Total assets	2,321.9				2,580				2,321.9	2,580	2,376.4
Operating Segments [Member] | United Kingdom [Member] | Risk Management [Member]
Segment Reporting Information [Line Items]
Total revenues									25.6	28.4	29.4
Total revenues									25.6	28.4	29.4
Total assets	61.8				72.1				61.8	72.1	74
Operating Segments [Member] | Australia [Member] | Brokerage [Member]
Segment Reporting Information [Line Items]
Total revenues									172.5	157.3	122.4
Total revenues									172.5	157.3	122.4
Total assets	894.4				895.8				894.4	895.8	992.2
Operating Segments [Member] | Australia [Member] | Risk Management [Member]
Segment Reporting Information [Line Items]
Total revenues									73	99.4	114.2
Total revenues									73	99.4	114.2
Total assets	56.9				55.6				56.9	55.6	39
Operating Segments [Member] | Canada [Member] | Brokerage [Member]
Segment Reporting Information [Line Items]
Total revenues									134.1	133.1	81.8
Total revenues									134.1	133.1	81.8
Total assets	573.3				575				573.3	575	639.2
Operating Segments [Member] | Canada [Member] | Risk Management [Member]
Segment Reporting Information [Line Items]
Total revenues									4.1	3.5	3.2
Total revenues									4.1	3.5	3.2
Total assets	2.8				3.1				2.8	3.1	2.8
Operating Segments [Member] | New Zealand [Member] | Brokerage [Member]
Segment Reporting Information [Line Items]
Total revenues									120.7	118.6	78.4
Total revenues									120.7	118.6	78.4
Total assets	668.9				623.1				668.9	623.1	614.1
Operating Segments [Member] | New Zealand [Member] | Risk Management [Member]
Segment Reporting Information [Line Items]
Total revenues									5.1	4	2.9
Total revenues									5.1	4	2.9
Total assets	4.4				4.1				4.4	4.1	1.6
Operating Segments [Member] | Other Foreign [Member] | Brokerage [Member]
Segment Reporting Information [Line Items]
Total revenues									79.7	54.4	43.6
Total revenues									79.7	54.4	43.6
Total assets	331.3				203				331.3	203	207.2
Operating Segments [Member] | Other Foreign [Member] | Corporate [Member]
Segment Reporting Information [Line Items]
Total revenues									20.9	13.8	11
Total revenues									20.9	13.8	11
Total assets	$ 17.6				$ 19.1				$ 17.6	$ 19.1	$ 16.9

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	$ 13.3	$ 10.7	$ 6.7
Amounts Recorded in Earnings	4.9	5.7	2.7
Adjustments	(5.4)	(3.1)	1.3
Balance at End of Year	12.8	13.3	10.7
Allowance for Estimated Policy Cancellations [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	7.4	6.8	4.2
Amounts Recorded in Earnings	0.2	3.6	(0.2)
Adjustments	(0.5)	(3)	2.8
Balance at End of Year	7.1	7.4	6.8
Accumulated Amortization of Expiration Lists, Noncompete Agreements and Trade Names [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	983.9	758.8	544.1
Amounts Recorded in Earnings	247.2	240.3	189.5
Adjustments	(27.5)	(15.2)	25.2
Balance at End of Year	$ 1,203.6	$ 983.9	$ 758.8