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Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2017	Nov. 01, 2017
Document and Entity Information
Entity Registrant Name	AFFILIATED MANAGERS GROUP, INC.
Entity Central Index Key	0001004434
Document Type	10-Q
Document Period End Date	Sep. 30, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		55,581,915
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q3

CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Revenue	$ 585.7	$ 544.7	$ 1,700.9	$ 1,644.2
Operating expenses:
Compensation and related expenses	238.7	244.2	722.9	702.9
Selling, general and administrative	91.9	94.2	269.7	286.7
Intangible amortization and impairments	21.2	26.9	65.1	82.2
Depreciation and other amortization	4.8	5.0	14.9	15.0
Other operating expenses (net)	10.3	3.4	32.0	25.9
Total operating expense (net)	366.9	373.7	1,104.6	1,112.7
Operating income before equity method investments	218.8	171.0	596.3	531.5
Income from equity method investments	70.7	67.5	231.6	200.7
Operating income	289.5	238.5	827.9	732.2
Non-operating (income) and expenses:
Investment and other income	(15.6)	(11.0)	(44.7)	(26.7)
Interest expense	21.5	22.4	65.8	66.4
Imputed interest expense and contingent payment arrangements	0.7	0.9	3.7	(0.2)
Total non-operating (income) and expenses	6.6	12.3	24.8	39.5
Income before income taxes	282.9	226.2	803.1	692.7
Income taxes	66.1	50.3	188.2	159.7
Net income	216.8	175.9	614.9	533.0
Net income (non-controlling interests)	(91.4)	(65.7)	(240.7)	(210.5)
Net income (controlling interest)	$ 125.4	$ 110.2	$ 374.2	$ 322.5
Average shares outstanding—basic (in shares)	55.8	53.9	56.3	53.9
Average shares outstanding—diluted (in shares)	58.3	56.6	58.8	56.6
Earnings per share—basic (in dollars per share)	$ 2.25	$ 2.04	$ 6.65	$ 5.98
Earnings per share—diluted (in dollars per share)	2.22	2.02	6.57	5.90
Dividends per share (in dollars per share)	$ 0.2	$ 0	$ 0.60	$ 0

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 216.8	$ 175.9	$ 614.9	$ 533.0
Controlling interest:
Foreign currency translation gain (loss)	47.5	(7.4)	79.0	(41.2)
Change in net realized and unrealized gain (loss) on derivative securities, net of tax	0.2	0.1	(1.7)	0.0
Change in net unrealized gain (loss) on investment securities, net of tax	(4.4)	2.8	(5.5)	(21.5)
Other comprehensive income (loss) (controlling interest)	43.3	(4.5)	71.8	(62.7)
Non-controlling interest:
Foreign currency translation gain (loss)	5.5	(9.4)	13.1	(31.5)
Change in net realized and unrealized gain (loss) on derivative securities, net of tax	(0.1)	0.0	0.9	(0.7)
Change in net unrealized gain (loss) on investment securities, net of tax	0.1	1.2	2.1	0.7
Other comprehensive income (loss) (non-controlling interest)	5.5	(8.2)	16.1	(31.5)
Other comprehensive income (loss)	48.8	(12.7)	87.9	(94.2)
Comprehensive income	265.6	163.2	702.8	438.8
Comprehensive income (non-controlling interests)	(96.9)	(57.5)	(256.8)	(179.0)
Comprehensive income (controlling interest)	$ 168.7	$ 105.7	$ 446.0	$ 259.8

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Assets
Cash and cash equivalents	$ 374.7	$ 430.8
Receivables	487.4	383.3
Investments in marketable securities	92.4	122.4
Other investments	160.5	147.5
Fixed assets (net)	111.7	110.1
Goodwill	2,661.8	2,628.1
Acquired client relationships (net)	1,467.2	1,497.4
Equity method investments in Affiliates	3,290.8	3,368.3
Other assets	54.9	61.2
Total assets	8,701.4	8,749.1
Liabilities and Equity
Payables and accrued liabilities	698.3	729.3
Senior bank debt	868.9	868.6
Senior notes	741.0	939.4
Convertible securities	303.7	301.6
Deferred income taxes	702.3	660.8
Other liabilities	178.3	149.4
Total liabilities	3,492.5	3,649.1
Commitments and contingencies
Redeemable non-controlling interests	804.6	673.5
Equity:
Common stock ($0.01 par value, 153.0 shares authorized; 58.5 shares outstanding in 2016 and 2017)	0.6	0.6
Additional paid-in capital	849.7	1,073.5
Accumulated other comprehensive loss	(51.1)	(122.9)
Retained earnings	3,394.4	3,054.4
Total stockholders' equity before treasury stock	4,193.6	4,005.6
Less: Treasury stock, at cost (1.8 shares in 2016 and 2.9 shares in 2017)	(566.1)	(386.0)
Total stockholders' equity	3,627.5	3,619.6
Non-controlling interests	776.8	806.9
Total equity	4,404.3	4,426.5
Total liabilities and equity	$ 8,701.4	$ 8,749.1

CONSOLIDATED BALANCE SHEETS CONSOLIDATED BALANCE SHEETS - Parenthetical - $ / shares shares in Millions	Sep. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	153.0	153.0
Common stock, shares outstanding (in shares)	58.5	58.5
Treasury stock, at cost (in shares)	2.9	1.8

CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Treasury Stock at Cost	Non-controlling Interests
Beginning Balance (in shares) at Dec. 31, 2015		55.8
Beginning Balance at Dec. 31, 2015	$ 3,769.1	$ 0.6	$ 694.9	$ (18.1)	$ 2,581.6	$ (421.9)	$ 932.0
Increase (Decrease) in Stockholders' Equity
Net income	533.0				322.5		210.5
Other comprehensive income	(94.2)			(62.7)			(31.5)
Share-based compensation	30.7		30.7
Common stock issued under share-based incentive plans	6.2		(35.6)			41.8
Share repurchases	(33.4)					(33.4)
Issuance costs and other	(2.3)		(2.3)
Common stock issued under forward equity agreement (in shares)		0.9
Common stock issued under forward equity agreement	150.3	$ 0.0	150.3
Affiliate equity activity:
Affiliate equity expense	34.9		7.7				27.2
Issuances	11.7		(2.5)				14.2
Repurchases	14.4		14.0				0.4
Changes in redemption value of Redeemable non-controlling interests	(84.9)		(84.9)
Transfers to Redeemable non-controlling interests	(38.3)						(38.3)
Capital contributions by Affiliate equity holders	2.7						2.7
Distributions to non-controlling interests	(270.1)						(270.1)
Ending Balance (in shares) at Sep. 30, 2016		56.7
Ending Balance at Sep. 30, 2016	$ 4,029.8	$ 0.6	772.3	(80.8)	2,904.1	(413.5)	847.1
Beginning Balance (in shares) at Dec. 31, 2016	58.5	58.5
Beginning Balance at Dec. 31, 2016	$ 4,426.5	$ 0.6	1,073.5	(122.9)	3,054.4	(386.0)	806.9
Increase (Decrease) in Stockholders' Equity
Net income	614.9				374.2		240.7
Other comprehensive income	87.9			71.8			16.1
Share-based compensation	30.0		30.0
Common stock issued under share-based incentive plans	14.5		(81.8)			96.3
Share repurchases	(276.4)					(276.4)
Dividends	(34.2)				(34.2)
Issuance costs and other	0.6		0.6
Affiliate equity activity:
Affiliate equity expense	38.6		9.4				29.2
Issuances	2.8		(0.2)				3.0
Repurchases	34.6		34.6
Changes in redemption value of Redeemable non-controlling interests	(216.4)		(216.4)
Transfers to Redeemable non-controlling interests	(56.8)						(56.8)
Capital contributions by Affiliate equity holders	4.5						4.5
Distributions to non-controlling interests	$ (266.8)						(266.8)
Ending Balance (in shares) at Sep. 30, 2017	58.5	58.5
Ending Balance at Sep. 30, 2017	$ 4,404.3	$ 0.6	$ 849.7	$ (51.1)	$ 3,394.4	$ (566.1)	$ 776.8

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flow from (used in) operating activities:
Net income	$ 614.9	$ 533.0
Adjustments to reconcile Net income to net Cash flow from operating activities:
Intangible amortization and impairments	65.1	82.2
Depreciation and other amortization	14.9	15.0
Deferred income tax provision	80.3	69.8
Income from equity method investments, net of amortization	(231.6)	(200.7)
Distributions of earnings received from equity method investments	368.0	287.0
Amortization of issuance costs	3.3	3.6
Share-based compensation and Affiliate equity expense	68.6	65.6
Other non-cash items	(30.7)	(14.3)
Changes in assets and liabilities:
Purchases of trading securities by Affiliate sponsored consolidated products	(24.1)	(62.5)
Sales of trading securities by Affiliate sponsored consolidated products	23.2	59.1
(Increase) decrease in receivables	(131.7)	37.7
Increase in other assets	(3.6)	(3.9)
Decrease in payables, accrued liabilities and other liabilities	(16.1)	(187.1)
Cash flow from operating activities	800.5	684.5
Cash flow from (used in) investing activities:
Investments in Affiliates	(30.3)	(884.9)
Purchase of fixed assets	(13.9)	(15.1)
Purchase of investment securities	(22.2)	(10.2)
Sale of investment securities	71.3	41.5
Cash flow from (used in) investing activities	4.9	(868.7)
Cash flow from (used in) financing activities:
Borrowings of senior debt	445.0	900.0
Repayments of senior debt	(645.0)	(670.0)
Issuance of common stock	33.7	163.2
Dividends paid on common stock	(33.8)	0.0
Repurchase of common stock	(276.4)	(33.4)
Distributions to non-controlling interests	(266.8)	(270.1)
Affiliate equity issuances and repurchases	(112.5)	(70.3)
Settlement of forward equity sale agreement	5.2	0.0
Other financing items	(20.9)	17.2
Cash flow from (used in) financing activities	(871.5)	36.6
Effect of foreign exchange rate changes on cash and cash equivalents	10.0	(19.7)
Net decrease in cash and cash equivalents	(56.1)	(167.3)
Cash and cash equivalents at beginning of period	430.8	563.8
Net cash inflows upon the consolidation and deconsolidation of Affiliate sponsored products	0.0	25.5
Cash and cash equivalents at end of period	$ 374.7	$ 422.0

Basis of Presentation and Use of Estimates	9 Months Ended
Basis of Presentation and Use of Estimates	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Use of Estimates	Basis of Presentation and Use of Estimates The Consolidated Financial Statements of Affiliated Managers Group, Inc. (the “Company”) have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for full year financial statements. In the opinion of management, all normal and recurring adjustments considered necessary for a fair presentation of the Company’s financial position and results of operations have been included and all intercompany balances and transactions have been eliminated. During the second quarter of 2017, the Company changed its Consolidated Statement of Income presentation to include Income from equity method investments in Operating income, as its equity method Affiliates are integral to the Company’s operations. This change, along with other reclassifications, has been made to the prior period’s financial statements to conform to the current period’s presentation. Operating results for interim periods are not necessarily indicative of the results that may be expected for any other period or for the full year. The Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2016 includes additional information about its operations, financial position and accounting policies, and should be read in conjunction with this Quarterly Report on Form 10-Q. The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts and disclosures in the financial statements. Actual results could differ from those estimates. All amounts in these notes, except per share data in the text and tables herein, are stated in millions unless otherwise indicated.

Recent Accounting Developments	9 Months Ended
Recent Accounting Developments	Sep. 30, 2017
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recent Accounting Developments	Recent Accounting Developments Effective January 1, 2017, the Company adopted Accounting Standard Update (“ASU”) 2016-07, Investments - Equity Method and Joint Ventures: Simplifying the Transition to the Equity Method of Accounting, and ASU 2016-06, Derivatives, and Hedging: Contingent Put and Call Options in Debt Instruments. The adoption of these updates did not have a significant impact on the Company’s Consolidated Financial Statements. In May 2014, the Financial Accounting Standards Board (the “FASB”) issued ASU 2014-09, Revenue from Contracts with Customers, and subsequently issued several related amendments. The standard provides a comprehensive model for revenue recognition and is effective for the Company and its consolidated Affiliates for interim and annual periods beginning after December 15, 2017 and for interim and annual periods beginning after December 15, 2018 for the Company’s equity method Affiliates. The standard may be adopted using either the full or modified retrospective method. The Company has not yet selected its transition method and continues to evaluate the impact of this standard on its Consolidated Financial Statements, but it does not expect the adoption to significantly impact the timing of the recognition of its Revenue. The Company is evaluating whether certain costs currently expensed as incurred meet the criteria for capitalization and whether certain revenue-related costs will be presented on a gross or net basis. In January 2016, the FASB issued ASU 2016-01, Fair Value: Recognition and Measurement of Financial Assets and Liabilities. Under the new standard, all equity investments in unconsolidated entities (other than those accounted for using the equity method of accounting) will generally be measured at fair value with any changes recognized through earnings. The standard is effective for interim and annual periods beginning after December 15, 2017 and must be adopted using a modified retrospective method. The impact of this standard on the Company’s Consolidated Financial Statements will depend on the equity investments held by the Company at the time of adoption. In February 2016, the FASB issued ASU 2016-02, Leases, which requires lessees to recognize assets and liabilities arising from most operating leases on the statement of financial position. The standard is effective for interim and annual periods beginning after December 15, 2018 for the Company and its consolidated Affiliates and for interim and annual periods beginning after December 15, 2019 for the Company’s equity method Affiliates. The standard must be adopted using a modified retrospective method. The Company is evaluating the impact of this standard on its Consolidated Financial Statements. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows - Classification of Certain Cash Receipts and Cash Payments, which clarifies how cash receipts and cash payments are classified in the statement of cash flows. The standard is effective for interim and annual periods beginning after December 15, 2017 and must be adopted using a full retrospective method. The Company does not expect the adoption of this standard to have a significant impact on its Consolidated Financial Statements. In January 2017, the FASB issued ASU 2017-01, Clarifying the Definition of a Business, which provides guidance on evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The standard is effective for interim and annual periods beginning after December 15, 2017. The Company will apply the standard prospectively upon adoption. The impact of this standard on the Company’s Consolidated Financial Statements will depend on acquisitions (or disposals) of assets or businesses by the Company in periods following adoption. In January 2017, the FASB issued ASU 2017-04, Intangibles - Goodwill and Other: Simplifying the Accounting for Goodwill Impairment. Under the new standard, a goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value. The standard is effective for interim and annual periods beginning after December 15, 2019. The Company will apply the standard prospectively upon adoption. The Company is evaluating the impact of this standard on its Consolidated Financial Statements. In May 2017, the FASB issued ASU 2017-09, Compensation - Stock Compensation, which simplifies modification accounting related to share-based arrangements. Under the new standard, modification assessments will not be required if fair value, vesting conditions and classification would be unaffected by a modification. The standard is effective for interim and annual periods beginning after December 15, 2017. The Company will apply the standard prospectively upon adoption. The Company does not expect the adoption of this standard to have a significant impact on its Consolidated Financial Statements.

- Definition

The entire disclosure of changes in accounting principles, including adoption of new accounting pronouncements, that describes the new methods, amount and effects on financial statement line items.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Change in Accounting Principle
-URI http://asc.fasb.org/extlink&oid=6507316

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Direct Effects of a Change in Accounting Principle
-URI http://asc.fasb.org/extlink&oid=66092750

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64853466&loc=d3e22583-107794

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Indirect Effects of a Change in Accounting Principle
-URI http://asc.fasb.org/extlink&oid=6515603

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64853466&loc=d3e22580-107794

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 270
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.10-01.(b)(6))
-URI http://asc.fasb.org/extlink&oid=27015980&loc=d3e46468-122699

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Accounting Change
-URI http://asc.fasb.org/extlink&oid=6503790

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=64853466&loc=d3e22499-107794

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Retrospective Application
-URI http://asc.fasb.org/extlink&oid=6523989

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 270
-SubTopic 10
-Section 45
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=68064558&loc=d3e765-108305

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 270
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=68064558&loc=d3e725-108305

+ Details

Investments in Marketable Securities

9 Months Ended

Sep. 30, 2017

Marketable Securities [Abstract]

Investments in Marketable Securities

Investments in marketable securities at December 31, 2016 and September 30, 2017 were $122.4 million and $92.4 million, respectively. The following is a summary of the cost, gross unrealized gains and losses and fair value of investments classified as available-for-sale and trading:



	Available-for-Sale					Trading
	December 31, 2016			September 30, 2017		December 31, 2016			September 30, 2017
Cost	$	66.1		$	30.5	$	34.4		$	44.2
Unrealized gains	17.6			10.8		6.6			8.5
Unrealized losses	(1.8		)	—		(0.5		)	(1.6		)
Fair Value	$	81.9		$	41.3	$	40.5		$	51.1

In the three and nine months ended September 30, 2016, the Company received proceeds of $12.6 million and $47.0 million, respectively, from the sale of investments classified as available-for-sale and recorded gains of $6.2 million and $15.4 million, respectively. In the three and nine months ended September 30, 2017, the Company received proceeds of $15.4 million and $58.7 million, respectively, from the sale of investments classified as available-for-sale and recorded gains of $7.4 million and $19.2 million, respectively. There were no significant realized gains or losses on investments classified as trading in the three and nine months ended September 30, 2016. In the three and nine months ended September 30, 2017, the Company received proceeds of $8.2 million and $23.2 million, respectively, from the sale of investments classified as trading and recorded net gains of $1.7 million and $5.0 million, respectively. The realized gains and losses on securities held in Affiliate sponsored consolidated products were recorded in Other operating expenses (net), other realized gains and losses were recorded in Investment and other income.

- Definition

The entire disclosure for investments in certain debt and equity securities.

+ References + Details

Investments in Affiliates and Affiliate Sponsored Investments Products

9 Months Ended

Sep. 30, 2017

Variable Interest Entities

Investments in Affiliates and Affiliate Sponsored Investments Products

Investments in Affiliates and Affiliate Sponsored Investment Products

Investments in Affiliates

The Company’s Affiliates are consolidated or accounted for under the equity method, depending upon the underlying structure of and relationship with each Affiliate.

A limited number of the Company’s Affiliates are considered voting rights entities (“VREs”) because the total equity investment at risk is sufficient to enable the entities to finance their respective activities independently and each entity’s equity holders have the right to receive residual returns, the obligation to absorb losses and the right to direct the activities of the entity that most significantly impact its economic performance. Most of the Company’s Affiliates considered VREs are accounted for under the equity method because the Company lacks control, but is deemed to have significant influence.

Substantially all of the Company’s Affiliates are considered variable interest entities (“VIEs”) because they are structured as partnerships (or similar entities) and the limited partners lack substantive kick-out or substantive participation rights over the general partner. The Company consolidates a VIE when it is the primary beneficiary of the entity, which is defined as having the power to direct the activities that most significantly impact the VIE’s economic performance and the right to receive benefits from or the obligation to absorb losses of the entity that could potentially be significant to the VIE. The Company applies the equity method of accounting to a VIE when it is not the primary beneficiary, but is deemed to have significant influence.

The unconsolidated assets, net of liabilities and non-controlling interests of equity method Affiliates considered VIEs, and the Company’s maximum risk of loss were as follows:



	December 31, 2016				September 30, 2017
	Unconsolidated VIE Net Assets		Carrying Value and Maximum Exposure to Loss		Unconsolidated VIE Net Assets		Carrying Value and Maximum Exposure to Loss
Affiliates accounted for under the equity method	$	1,047.6	$	2,846.8	$	1,019.4	$	2,749.7

Affiliate Sponsored Investment Products

The Company’s consolidated Affiliates sponsor various investment products for which they also act as the investment advisor. These investment products are primarily owned by third-party investors; however, certain products are funded with general partner and seed capital investments from the Company and its Affiliates. Third-party investors are generally entitled to substantially all of the economics of these products.

Certain of the Company’s Affiliate sponsored investment products are considered VIEs because they are structured as partnerships (or similar entities) and the limited partners lack substantive kick-out or substantive participation rights over the general partner. The Company's Affiliates’ involvement with sponsored investment products is generally limited to that of a service provider, and their seed capital investments, if any, represent an insignificant interest in the relevant investment products’ net assets. The Company’s and its consolidated Affiliates’ exposure to risk in these entities is generally limited to any capital contribution made or required to be made and any earned but uncollected management and performance fees. As a result, in most cases these VIEs are not consolidated and are accounted for under the equity method because neither the Company nor its Affiliates are deemed to be the primary beneficiary.

The net assets of Affiliate sponsored investment products that were considered VIEs accounted for under the equity method and the Company’s maximum risk of loss were as follows:



	December 31, 2016				September 30, 2017
	Unconsolidated VIE Net Assets		Carrying Value and Maximum Exposure to Loss		Unconsolidated VIE Net Assets		Carrying Value and Maximum Exposure to Loss
Affiliate sponsored investment products	$	1,756.6	$	9.4	$	1,961.5	$	9.9

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies From time to time, the Company and its Affiliates may be subject to claims, legal proceedings and other contingencies in the ordinary course of their business activities. Any such matters are subject to various uncertainties, and it is possible that some of these matters may be resolved in a manner unfavorable to the Company or its Affiliates. The Company and its Affiliates establish accruals, as necessary, for matters for which the outcome is probable and the amount of the liability can be reasonably estimated. Third Avenue Management LLC (“Third Avenue”), one of the Company’s consolidated Affiliates, was named as a defendant in various legal actions relating to the liquidation and closure of the Third Avenue Focused Credit Fund. The Company was named as a co-defendant in one of these actions, as a purported control person. In 2016, Third Avenue recorded a reserve of $15.0 million in connection with the proposed resolution of all claims related to the Focused Credit Fund. These claims, including those against the Company, were subsequently resolved in a court-approved settlement, and Third Avenue and its insurers paid amounts due under the settlement during the quarter and no additional expense was recognized. The Company has committed to co-invest in certain Affiliate sponsored investment products. As of September 30, 2017, these unfunded commitments were $94.9 million and may be called in future periods. As of September 30, 2017, the Company was contingently liable, upon the achievement by certain Affiliates of specified financial targets, to make payments related to the Company’s investments in these Affiliates through 2019. For its consolidated Affiliates, the Company was contingently liable for up to $21.7 million, and expected to make payments of $8.9 million ($1.6 million in 2017). The present value of these expected payments was $8.1 million. For its equity method Affiliates, the Company was contingently liable for up to $170.0 million, and expected to make no payments. Affiliate equity interests provide holders with a conditional right to put their interests to the Company over time. See Note 13. In addition, in connection with an investment in an Affiliate accounted for under the equity method, the Company entered into an arrangement with a minority owner of the Affiliate that gives such owner the right to sell a portion of its ownership interest in the Affiliate to the Company annually beginning in the fourth quarter of 2018. The purchase price of these conditional purchases will be at fair market value on the date of the transaction. The Company and certain consolidated Affiliates operate under regulatory authorities that require that they maintain minimum financial or capital requirements. Management is not aware of any significant violations of such requirements.

Senior Notes	9 Months Ended
Senior Notes	Sep. 30, 2017
Debt Disclosure [Abstract]
Senior Notes	Senior Notes In the three months ended September 30, 2017, the Company redeemed all $200.0 million principal amount outstanding of its 6.375% senior unsecured notes due 2042 at a redemption price equal to 100% of the principal amount. The notes were subsequently canceled and retired.

Fair Value Measurements

9 Months Ended

Sep. 30, 2017

Fair Value Disclosures [Abstract]

Fair Value Measurements

The following tables summarize the Company’s financial assets and liabilities that are measured at fair value on a recurring basis:



			Fair Value Measurements
	December 31, 2016		Fair Value Measurements
	December 31, 2016		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)
Financial Assets
Cash equivalents	$	64.1	$	64.1	$	—	$	—
Investments in marketable securities⁽¹⁾
Trading securities	40.5		40.5		—		—
Available-for-sale securities	81.9		81.9		—		—
Other investments	3.4		3.4		—		—
Foreign currency forward contracts⁽²⁾	0.6		—		0.6		—
Financial Liabilities⁽²⁾
Contingent payment arrangements	$	8.6	$	—	$	—	$	8.6
Affiliate equity obligations	12.1		—		—		12.1
Foreign currency forward contracts	0.5		—		0.5		—



			Fair Value Measurements
	September 30, 2017		Fair Value Measurements
	September 30, 2017		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)
Financial Assets
Cash equivalents	$	35.1	$	35.1	$	—	$	—
Investments in marketable securities⁽¹⁾
Trading securities	51.1		51.1		—		—
Available-for-sale securities	41.3		41.3		—		—
Foreign currency forward contracts⁽²⁾	0.7		—		0.7		—
Financial Liabilities⁽²⁾
Contingent payment arrangements	$	8.1	$	—	$	—	$	8.1
Affiliate equity obligations	45.7		—		—		45.7
Foreign currency forward contracts	1.0		—		1.0		—

__________________________


⁽¹⁾	Principally investments in equity securities.


⁽²⁾	Amounts are presented within Other assets or Other liabilities.

The following are descriptions of the significant financial assets and liabilities measured at fair value and the fair value methodologies used.

Cash equivalents consist primarily of highly liquid investments in daily redeeming money market funds, without enacted liquidity fees or redemption gates that are valued at net asset value (“NAV”).

Investments in marketable securities consist primarily of investments in publicly traded securities and funds advised by Affiliates that are valued at NAV. Publicly traded securities valued using unadjusted quoted market prices for identical instruments in active markets are classified as level 1. Publicly traded securities valued using quoted prices for similar instruments in active markets or quoted prices for identical or similar instruments in markets that are not active are classified as level 2. Investments in funds advised by Affiliates that are valued at NAV are classified as level 1.

Contingent payment arrangements represent the present value of the expected future settlement of contingent payment arrangements related to the Company’s investments in consolidated Affiliates. The significant unobservable inputs that are used in the fair value measurement of these obligations are growth and discount rates. Increases in the growth rate result in a higher obligation while increases in the discount rate result in a lower obligation.

Affiliate equity obligations include agreements to repurchase Affiliate equity. The significant unobservable inputs that are used in the fair value measurement of the agreements to repurchase Affiliate equity are growth and discount rates. Increases in the growth rate result in a higher obligation while increases in the discount rate result in a lower obligation.

Foreign currency forward contracts use model-derived valuations in which all significant inputs are observable in active markets to determine fair value.

It is the Company’s policy to value financial assets or liabilities transferred as of the beginning of the period in which the transfer occurs. There were no significant transfers of financial assets or liabilities between level 1 and level 2 in the three and nine months ended September 30, 2016 and 2017.

Level 3 Financial Assets and Liabilities

The following tables present the changes in level 3 liabilities:



	For the Three Months Ended September 30,
	2016						2017
	Contingent Payment Arrangements			Affiliate Equity Obligations			Contingent Payment Arrangements			Affiliate Equity Obligations
Balance, beginning of period	$	8.0		$	27.0		$	7.8		$	70.7
Net realized and unrealized (gains) losses	0.2		⁽¹⁾	0.1			0.3		⁽¹⁾	(0.2		)
Purchases and issuances	—			8.4			—			11.1
Settlements and reductions	—			(8.8		)	—			(35.9		)
Balance, end of period	$	8.2		$	26.7		$	8.1		$	45.7

Net change in unrealized (gains) losses relating to instruments still held at the reporting date	$	0.2	⁽¹⁾	$	—		$	0.3	⁽¹⁾	$	—



	For the Nine Months Ended September 30,
	2016							2017
	Contingent Payment Arrangements				Affiliate Equity Obligations			Contingent Payment Arrangements				Affiliate Equity Obligations
Balance, beginning of period	$	10.2			$	62.3		$	8.6			$	12.1
Net realized and unrealized (gains) losses	(2.0		)	⁽¹⁾	0.1			2.3			⁽¹⁾	(0.2		)
Purchases and issuances	—				48.2			—				161.5
Settlements and reductions	—				(83.9		)	(2.8		)		(127.7		)
Balance, end of period	$	8.2			$	26.7		$	8.1			$	45.7

Net change in unrealized (gains) losses relating to instruments still held at the reporting date	$	(2.0	)	⁽¹⁾	$	—		2.3			⁽¹⁾	$	—

___________________________


⁽¹⁾	Accretion and changes in the expected value of the Company’s contingent payment arrangements are recorded in Imputed interest expense and contingent payment arrangements.

The following table presents certain quantitative information about the significant unobservable inputs used in valuing the Company’s level 3 financial liabilities:



	Quantitative Information About Level 3 Fair Value Measurements
	Valuation Techniques	Unobservable Input	Fair Value at December 31, 2016		Range at December 31, 2016	Fair Value at September 30, 2017		Range at September 30, 2017
Contingent payment arrangements	Discounted cash flow	Growth rates	$	8.6	3% - 8%	$	8.1	8% - 9%
		Discount rates			14% - 15%			14% - 15%
Affiliate equity obligations	Discounted cash flow	Growth rates	12.1		4% - 10%	45.7		5% - 9%
		Discount rates			15% - 16%			12% - 16%

Investments Measured at NAV as a Practical Expedient

The Company’s Affiliates sponsor investment products in which the Company and Affiliates may make general partner and seed capital investments. The Company uses the NAV of these investments as a practical expedient for their fair value. The following table summarizes the nature of the Company’s investments, unfunded commitments and any related liquidity restrictions or other factors that may impact the ultimate value realized:



	December 31, 2016				September 30, 2017
Category of Investment	Fair Value		Unfunded Commitments		Fair Value		Unfunded Commitments
Private equity funds⁽¹⁾	$	137.8	$	92.2	$	151.9	$	94.9
Other funds⁽²⁾	9.7		—		8.6		—
Other investments⁽³⁾	$	147.5	$	92.2	$	160.5	$	94.9

___________________________


⁽¹⁾	The Company uses NAV as a practical expedient one quarter in arrears (adjusted for current period calls and distributions) to determine the fair value. These funds primarily invest in a broad range of private equity funds, as well as making direct investments. Distributions will be received as the underlying assets are liquidated over the life of the funds, which is generally up to 15 years.


⁽²⁾	These are multi-disciplinary funds that invest across various asset classes and strategies, including long/short equity, credit and real estate. Investments are generally redeemable on a daily, monthly or quarterly basis.


⁽³⁾	Fair value attributable to the controlling interest was $59.9 million and $72.8 million as of December 31, 2016 and September 30, 2017, respectively.

Other Financial Assets and Liabilities Not Carried at Fair Value

The carrying amount of Receivables and Payables and accrued liabilities approximates fair value because of the short-term nature of these instruments. The carrying value of notes receivable, which is reported in Other assets, approximates fair value because interest rates and other terms are at market rates. The carrying value of the credit facilities, which is reported in Senior bank debt, approximates fair value because the debt has variable interest based on selected short-term rates. The following table summarizes the Company’s other financial liabilities not carried at fair value:



	December 31, 2016				September 30, 2017
	Carrying Value		Fair Value		Carrying Value		Fair Value		Fair Value Hierarchy
Senior notes	$	945.1	$	936.0	$	745.5	$	779.6	Level 2
Convertible securities	307.5		466.9		309.3		527.8		Level 2

- Definition

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

+ References + Details

Goodwill and Acquired Client Relationships

9 Months Ended

Sep. 30, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Acquired Client Relationships

The following tables present the changes in the Company’s consolidated Affiliates’ Goodwill and components of Acquired client relationships (net):



	Goodwill
	Total
Balance, as of December 31, 2016	$	2,628.1
Foreign currency translation	33.7
Balance, as of September 30, 2017	$	2,661.8

As of September 30, 2017, the Company completed its impairment assessments on its goodwill and no impairments were indicated.



	Acquired Client Relationships
	Definite-lived								Indefinite-lived		Total
	Gross Book Value		Accumulated Amortization			Net Book Value			Net Book Value		Net Book Value
Balance, as of December 31, 2016	$	1,290.0	$	(788.1	)	$	501.9		$	995.5	$	1,497.4
Intangible amortization and impairments	—		(65.1		)	(65.1		)	—		(65.1		)
Foreign currency translation	5.0		—			5.0			29.9		34.9
Balance, as of September 30, 2017	$	1,295.0	$	(853.2	)	$	441.8		$	1,025.4	$	1,467.2

Definite-lived acquired client relationships are amortized over their expected useful lives. As of September 30, 2017, these relationships were being amortized over a weighted average life of approximately 12 years. The Company recorded amortization expense, in Intangible amortization and impairments, for these relationships of $26.9 million and $82.2 million for the three and nine months ended September 30, 2016, respectively, and $21.2 million and $65.1 million for the three and nine months ended September 30, 2017, respectively. Based on relationships existing as of September 30, 2017, the Company estimates that its consolidated annual amortization expense will be approximately $85 million in each of 2017, 2018 and 2019, $50 million in 2020 and $30 million in 2021.

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

Equity Method Investments in Affiliates

9 Months Ended

Sep. 30, 2017

Equity Method Investments and Joint Ventures [Abstract]

Equity Method Investments in Affiliates

In 2016, the Company completed investments in Systematica Investments L.P. and Baring Private Equity Asia, both of which closed on January 4, 2016, Capula Investment Management, LLP, Mount Lucas Management LP and Capeview Capital LLP, all of which closed on July 1, 2016, Partner Fund Management, L.P., which closed on September 30, 2016, and Winton Group Ltd., which closed on October 4, 2016. The purchase price allocations were completed using financial models that included assumptions of expected market performance, net client cash flows and discount rates. The majority of the consideration paid is deductible for U.S. tax purposes over a 15-year life. The financial results of certain equity method Affiliates are recognized in the Consolidated Financial Statements one quarter in arrears.

The aggregate purchase price allocation for the 2016 investments was as follows:



	Total
Consideration paid	$	1,362.3

Definite-lived acquired client relationships	$	560.8
Indefinite-lived acquired client relationships	36.9
Tangible assets	2.0
Deferred tax liability	(91.8		)
Goodwill	854.4
	$	1,362.3

For these new investments, the Company recorded amortization expense on the definite-lived acquired client relationships of $3.7 million and $11.2 million in the three and nine months ended September 30, 2016, respectively, and $15.5 million and $33.9 million in the three and nine months ended September 30, 2017, respectively.

The following table presents the change in Equity method investments in Affiliates:



	Total
Balance, as of December 31, 2016	$	3,368.3
Equity method earnings	303.3
Equity method intangible amortization	(71.7		)
Distributions of earnings from equity method investments	(368.0		)
Investments	29.8
Foreign currency translation	32.1
Other	(3.0		)
Balance, as of September 30, 2017	$	3,290.8

As of September 30, 2017, the definite-lived relationships at all of the Company’s equity method Affiliates were being amortized over a weighted average life of approximately 10 years. The Company recognized amortization expense for these relationships of $14.0 million and $43.0 million for the three and nine months ended September 30, 2016, respectively, and $25.9 million and $71.7 million for the three and nine months ended September 30, 2017, respectively. Based on relationships existing as of September 30, 2017, the Company estimates the annual amortization expense attributable to its current equity method Affiliates will be approximately $100 million in each of 2017 and 2018 and $80 million in each of 2019, 2020 and 2021.

The Company has determined that one of its equity method Affiliates is significant under Rule 10-01(b)(1) of Regulation S-X. For the three and nine months ended September 30, 2016, this equity method Affiliate recognized revenue of $230.2 million and $658.6 million, respectively, and net income of $126.4 million and $361.0 million, respectively. For the three and nine months ended September 30, 2017, this equity method Affiliate recognized revenue of $301.8 million and $826.6 million, respectively, and net income of $178.3 million and $471.3 million, respectively.

Related Party Transactions	9 Months Ended
Related Party Transactions	Sep. 30, 2017
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions A prior owner of one of the Company’s Affiliates retained an interest in certain of the Affiliate’s private equity investment partnerships. The prior owner’s interest is presented in the Company’s Consolidated Balance Sheets as either a liability in Other liabilities or as Non-controlling interests, depending on the structure of the prior owner’s investments in the partnerships. The total liability was $67.8 million and $64.1 million at December 31, 2016 and September 30, 2017, respectively. The total non-controlling interest was $2.5 million and $0.8 million at December 31, 2016 and September 30, 2017, respectively. The Company and its Affiliates earn asset based revenue, performance fees, distribution and servicing and other fees and incur distribution and servicing and other expenses for services provided to Affiliate sponsored investment products. In addition, Affiliate management owners and Company officers may serve as trustees or directors of certain investment vehicles from which an Affiliate earns revenue. The Company has liabilities to related parties for contingent payment arrangements in connection with certain business combinations. The net present value of the total amounts payable were $8.6 million and $8.1 million as of December 31, 2016 and September 30, 2017, respectively, and were included in Other liabilities. The Company has related party transactions in association with its Affiliate equity transactions, as more fully described in Notes 12 and 13.

Share-Based Compensation

9 Months Ended

Sep. 30, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Share-Based Compensation

The following is a summary of share-based compensation expense:



	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2016		2017		2016		2017
Share-based compensation	$	10.7	$	10.3	$	30.7	$	30.0
Tax benefit	4.1		4.0		11.8		11.5

The Company had $66.4 million and $73.8 million of unrecognized share-based compensation as of December 31, 2016 and September 30, 2017, respectively, which will be recognized over a weighted average period of approximately three years (assuming no forfeitures).

Stock Options

The following table summarizes transactions in the Company’s stock options:



	Stock Options		Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (years)
Unexercised options outstanding - December 31, 2016	1.4		$	108.53
Options granted	0.0		168.60
Options exercised	(0.6	)	96.86
Options forfeited	(0.1	)	140.26
Unexercised options outstanding - September 30, 2017	0.7		118.35		3.5
Exercisable at September 30, 2017	0.3		108.55		1.5

For the nine months ended September 30, 2016 and 2017, the Company granted stock options with fair values of $16.4 million and $0.8 million, respectively. Stock options generally vest over a period of three to four years and expire seven years after the grant date. All options have been granted with exercise prices equal to the closing price of the Company’s common stock on the grant date. In certain circumstances, option awards also require certain performance conditions to be satisfied in order for the options to be exercised.

The fair value of options granted was estimated using the Black-Scholes option pricing model. For the nine months ended September 30, 2016 and 2017, the weighted average fair values of options granted were $39.02 and $48.05, per option, respectively, based on the weighted-average grant date assumptions stated below.



	For the Nine Months Ended September 30,
	2016		2017
Dividend yield	—		0.5	%
Expected volatility	30.7	%	28.0	%
Risk-free interest rate	1.6	%	2.1	%
Expected life of options (in years)	5.7		5.7
Forfeiture rate	—		—

Restricted Stock

The following table summarizes transactions in the Company’s restricted stock units:



	Restricted Stock Units		Weighted Average Grant Date Value
Unvested units - December 31, 2016	0.6		$	168.84
Units granted	0.2		153.09
Units vested	(0.2	)	167.72
Units forfeited	(0.0	)	170.52
Unvested units - September 30, 2017	0.6		162.97

For the nine months ended September 30, 2016 and 2017, the Company granted awards with fair values of $28.0 million and $36.7 million, respectively. These awards were valued based on the closing price of the Company’s common stock on the grant date and contain vesting conditions requiring service over a period of three to four years. In certain circumstances, awards also require certain performance conditions to be satisfied.

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References + Details

Redeemable Non-Controlling Interests

9 Months Ended

Sep. 30, 2017

Noncontrolling Interest [Abstract]

Redeemable Non-Controlling Interests

Affiliate equity interests provide holders with a ratable portion of ownership in one of the Company’s consolidated Affiliates, consistent with the structured partnership interests in place at the respective Affiliate. Affiliate equity holders generally have a conditional right to put their interests to the Company at certain intervals (between five and 15 years from the date the equity interest is received or on an annual basis following an Affiliate equity holder’s departure). The current redemption value of the Company’s Affiliate equity interests is presented as Redeemable non-controlling interests. Changes in the current redemption value are recorded to Additional paid-in capital. The following table presents the changes in Redeemable non-controlling interests:



	Redeemable Non-controlling interests
Balance, as of December 31, 2016	$	673.5
Changes attributable to consolidated products	9.5
Repurchases of redeemable Affiliate equity	(151.6		)
Transfers from non-controlling interests	56.8
Changes in redemption value	216.4
Balance, as of September 30, 2017	$	804.6

Affiliate Equity

9 Months Ended

Sep. 30, 2017

Affiliate Equity [Abstract]

Affiliate Equity

Affiliate equity interests are allocated income in a manner that is consistent with the structured partnership interests in place at the respective Affiliate. The Company’s Affiliates generally pay quarterly distributions to Affiliate equity holders. For the nine months ended September 30, 2016 and 2017, distributions paid to Affiliate equity holders were $270.1 million and $266.8 million, respectively.

The Company periodically repurchases Affiliate equity interests from and issues Affiliate equity interests to its Affiliate equity holders. For the nine months ended September 30, 2016 and 2017, the amount of cash paid for repurchases was $82.1 million and $121.3 million, respectively. For the nine months ended September 30, 2016 and 2017, the total amount of cash received for issuances was $11.8 million and $8.8 million, respectively.

Sales and repurchases of Affiliate equity generally occur at fair value; however, the Company also grants Affiliate equity to its Affiliate partners, employees and officers as a form of compensation. If the equity is issued for consideration below the fair value of the equity or repurchased for consideration above the fair value of the equity, then such difference is recorded as compensation expense over the requisite service period.

The following is a summary of Affiliate equity expense:



	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2016		2017		2016		2017
Controlling interest	$	3.2	$	2.3	$	7.7	$	9.4
Non-controlling interests	18.5		7.7		27.2		29.2
Total	$	21.7	$	10.0	$	34.9	$	38.6

The following is a summary of unrecognized Affiliate equity expense:



	Controlling Interest		Remaining Life	Non-controlling Interests		Remaining Life
December 31, 2016	$	31.3	4 years	$	70.7	5 years
September 30, 2017	33.0		4 years	82.5		5 years

The Company records amounts receivable from and payable to Affiliate equity holders in connection with the transfer of Affiliate equity interests that have not settled at the end of the period. The total amount receivable was $22.9 million and $10.9 million at December 31, 2016 and September 30, 2017, respectively, and was included in Other assets. The total amount payable was $12.1 million and $45.7 million as of December 31, 2016 and September 30, 2017, respectively, and was included in Other liabilities.

Effects of Changes in the Company’s Ownership in Affiliates

The Company periodically acquires interests from, and transfers interests to, Affiliate equity holders. Because these transactions do not result in a change of control, any gain or loss related to these transactions is recorded to Additional paid-in capital, which increases or decreases the controlling interest’s equity. No gain or loss related to these transactions is recognized in the Consolidated Statements of Income or Comprehensive Income.

While the Company presents the current redemption value of Affiliate equity within Redeemable non-controlling interests with changes in the current redemption value increasing or decreasing the controlling interest’s equity over time, the following table discloses the cumulative effect that ownership changes had on the controlling interest’s equity related only to Affiliate equity transactions that settled during the periods:



	For the Three Months Ended September 30,						For the Nine Months Ended September 30,
	2016			2017			2016			2017
Net income (controlling interest)	$	110.2		$	125.4		$	322.5		$	374.2
Increase / (decrease) in controlling interest paid-in capital from purchases and sales of Affiliate equity issuances	5.3			(0.3		)	1.9			(0.6		)
Decrease in controlling interest paid-in capital related to Affiliate equity repurchases	(2.1		)	(12.7		)	(23.4		)	(81.8		)
Net income attributable to controlling interest and transfers from Non-controlling interests	$	113.4		$	112.4		$	301.0		$	291.8

Income Taxes

9 Months Ended

Sep. 30, 2017

Income Tax Disclosure [Abstract]

Income Taxes

The consolidated income tax provision includes taxes attributable to the controlling interest and, to a lesser extent, taxes attributable to the non-controlling interests as follows:



	For the Three Months Ended September 30,						For the Nine Months Ended September 30,
	2016			2017			2016			2017
Controlling interest:
Current tax	$	29.5		$	39.6		$	84.2		$	102.0
Intangible-related deferred taxes	19.5			22.9			63.0			61.8
Other deferred taxes	1.1			1.6			8.4			18.7
Total controlling interest	50.1			64.1			155.6			182.5
Non-controlling interests:
Current tax	$	1.5		$	2.1		$	5.7		$	5.9
Deferred taxes	(1.3		)	(0.1		)	(1.6		)	(0.2		)
Total non-controlling interests	0.2			2.0			4.1			5.7
Provision for income taxes	$	50.3		$	66.1		$	159.7		$	188.2
Income before income taxes (controlling interest)	$	160.3		$	189.5		$	478.1		$	556.7
Effective tax rate attributable to controlling interest⁽¹⁾	31.3		%	33.8		%	32.5		%	32.8		%

__________________________


⁽¹⁾	Taxes attributable to the controlling interest divided by Income before income taxes (controlling interest).

Earnings Per Share

9 Months Ended

Sep. 30, 2017

Earnings Per Share [Abstract]

Earnings Per Share

The calculation of basic earnings per share is based on the weighted average number of shares of the Company’s common stock outstanding during the period. Diluted earnings per share is similar to basic earnings per share, but adjusts for the dilutive effect of the potential issuance of incremental shares of the Company’s common stock. The following is a reconciliation of the numerator and denominator used in the calculation of basic and diluted earnings per share available to common stockholders.



	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2016		2017		2016		2017
Numerator
Net income (controlling interest)	$	110.2	$	125.4	$	322.5	$	374.2
Interest expense on convertible securities, net of taxes	3.9		3.9		11.6		11.6
Net income (controlling interest), as adjusted	$	114.1	$	129.3	$	334.1	$	385.8
Denominator
Average shares outstanding (basic)	53.9		55.8		53.9		56.3
Effect of dilutive instruments:
Stock options and restricted stock units	0.5		0.3		0.5		0.3
Junior convertible securities	2.2		2.2		2.2		2.2
Average shares outstanding (diluted)	56.6		58.3		56.6		58.8

Average shares outstanding (diluted) in the table above exclude share awards that have not satisfied performance conditions and the anti-dilutive effect of the following shares:



	For the Three Months Ended September 30,		For the Nine Months Ended September 30,
	2016	2017	2016	2017
Stock options and restricted stock units	0.5	0.0	0.7	0.1
Shares subject to forward sale agreement	2.0	—	2.0	—

The Company may settle portions of its Affiliate equity purchases in shares of its common stock. Because it is the Company’s intent to settle these potential purchases in cash, the calculation of diluted earnings per share excludes any potential dilutive effect from possible share settlements of Affiliate equity purchases.

In the three and nine months ended September 30, 2017, the Company repurchased 0.4 million and 1.7 million shares, respectively, at an average price per share of $175.68 and $164.00, respectively.

Comprehensive Income

9 Months Ended

Sep. 30, 2017

Other Comprehensive Income (Loss), Net of Tax [Abstract]

Comprehensive Income

The following tables show the tax effects allocated to each component of Other comprehensive income (loss):



	For the Three Months Ended September 30,
	2016									2017
	Pre-Tax			Tax Benefit (Expense)			Net of Tax			Pre-Tax			Tax Benefit (Expense)			Net of Tax
Foreign currency translation adjustment	$	(16.8	)	$	—		$	(16.8	)	$	53.0		$	—		$	53.0
Change in net realized and unrealized gain (loss) on derivative securities	0.1			(0.0		)	0.1			0.2			(0.1		)	0.1
Change in net unrealized gain (loss) on investment securities	5.8			(1.8		)	4.0			(6.8		)	2.5			(4.3		)
Other comprehensive income (loss)	$	(10.9	)	$	(1.8	)	$	(12.7	)	$	46.4		$	2.4		$	48.8



	For the Nine Months Ended September 30,
	2016									2017
	Pre-Tax			Tax Benefit (Expense)			Net of Tax			Pre-Tax			Tax Benefit (Expense)			Net of Tax
Foreign currency translation adjustment	$	(72.7	)	$	—		$	(72.7	)	$	92.1		$	—		$	92.1
Change in net realized and unrealized gain (loss) on derivative securities	(0.6		)	(0.1		)	(0.7		)	(0.7		)	(0.1		)	(0.8		)
Change in net unrealized gain (loss) on investment securities	(34.6		)	13.8			(20.8		)	(6.6		)	3.2			(3.4		)
Other comprehensive income (loss)	$	(107.9	)	$	13.7		$	(94.2	)	$	84.8		$	3.1		$	87.9

The components of accumulated other comprehensive income (loss), net of taxes, were as follows:



	Foreign Currency Translation Adjustment			Realized and Unrealized Gains (Losses) on Derivative Securities			Unrealized Gains (Losses) on Investment Securities ⁽¹⁾			Total
Balance, as of December 31, 2016	$	(213.9	)	$	0.4		$	9.8		$	(203.7	)
Other comprehensive gain (loss) before reclassifications	92.1			(0.4		)	13.8			105.5
Amounts reclassified	—			(0.4		)	(17.2		)	(17.6		)
Net other comprehensive gain (loss)	92.1			(0.8		)	(3.4		)	87.9
Balance, as of September 30, 2017	$	(121.8	)	$	(0.4	)	$	6.4		$	(115.8	)

__________________________


⁽¹⁾	See Note 3 for amounts reclassified from Other comprehensive income (loss).

- Definition

The entire disclosure for comprehensive income, which includes, but is not limited to, 1) the amount of income tax expense or benefit allocated to each component of other comprehensive income, including reclassification adjustments, 2) the reclassification adjustments for each classification of other comprehensive income and 3) the ending accumulated balances for each component of comprehensive income.

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-URI http://asc.fasb.org/extlink&oid=6522872

+ Details

Segment Information	9 Months Ended
Segment Information	Sep. 30, 2017
Segment Reporting [Abstract]
Segment Information	Segment Information In the first quarter of 2017, the Company’s Chief Operating Decision Maker (the “CODM”) changed the manner in which he assesses the Company’s performance. In 2016, the CODM assessed the performance of the Company in three business segments representing three distribution channels. Given an increase in the number of the Company’s Affiliates accounted for under the equity method of accounting and changes in the way asset management services are delivered, during the first quarter of 2017, the CODM began to assess the performance of the Company as a single global active asset management company. As a result, the CODM now reviews information organized around one operating segment to evaluate and manage the Company’s business operations. Therefore, the Company has determined that it has one reportable segment. In connection with this change, the Company completed impairment assessments based on its former three distribution channels, as well as its single global active asset management reporting unit, and determined that there were no impairments under either approach.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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+ Details

Basis of Presentation and Use of Estimates (Policies)	9 Months Ended
Basis of Presentation and Use of Estimates (Policies)	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	All amounts in these notes, except per share data in the text and tables herein, are stated in millions unless otherwise indicated The Consolidated Financial Statements of Affiliated Managers Group, Inc. (the “Company”) have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for full year financial statements. In the opinion of management, all normal and recurring adjustments considered necessary for a fair presentation of the Company’s financial position and results of operations have been included and all intercompany balances and transactions have been eliminated. During the second quarter of 2017, the Company changed its Consolidated Statement of Income presentation to include Income from equity method investments in Operating income, as its equity method Affiliates are integral to the Company’s operations. This change, along with other reclassifications, has been made to the prior period’s financial statements to conform to the current period’s presentation. Operating results for interim periods are not necessarily indicative of the results that may be expected for any other period or for the full year. The Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2016 includes additional information about its operations, financial position and accounting policies, and should be read in conjunction with this Quarterly Report on Form 10-Q.
Use of Estimates	The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts and disclosures in the financial statements. Actual results could differ from those estimates.
Recent Accounting Developments	Recent Accounting Developments Effective January 1, 2017, the Company adopted Accounting Standard Update (“ASU”) 2016-07, Investments - Equity Method and Joint Ventures: Simplifying the Transition to the Equity Method of Accounting, and ASU 2016-06, Derivatives, and Hedging: Contingent Put and Call Options in Debt Instruments. The adoption of these updates did not have a significant impact on the Company’s Consolidated Financial Statements. In May 2014, the Financial Accounting Standards Board (the “FASB”) issued ASU 2014-09, Revenue from Contracts with Customers, and subsequently issued several related amendments. The standard provides a comprehensive model for revenue recognition and is effective for the Company and its consolidated Affiliates for interim and annual periods beginning after December 15, 2017 and for interim and annual periods beginning after December 15, 2018 for the Company’s equity method Affiliates. The standard may be adopted using either the full or modified retrospective method. The Company has not yet selected its transition method and continues to evaluate the impact of this standard on its Consolidated Financial Statements, but it does not expect the adoption to significantly impact the timing of the recognition of its Revenue. The Company is evaluating whether certain costs currently expensed as incurred meet the criteria for capitalization and whether certain revenue-related costs will be presented on a gross or net basis. In January 2016, the FASB issued ASU 2016-01, Fair Value: Recognition and Measurement of Financial Assets and Liabilities. Under the new standard, all equity investments in unconsolidated entities (other than those accounted for using the equity method of accounting) will generally be measured at fair value with any changes recognized through earnings. The standard is effective for interim and annual periods beginning after December 15, 2017 and must be adopted using a modified retrospective method. The impact of this standard on the Company’s Consolidated Financial Statements will depend on the equity investments held by the Company at the time of adoption. In February 2016, the FASB issued ASU 2016-02, Leases, which requires lessees to recognize assets and liabilities arising from most operating leases on the statement of financial position. The standard is effective for interim and annual periods beginning after December 15, 2018 for the Company and its consolidated Affiliates and for interim and annual periods beginning after December 15, 2019 for the Company’s equity method Affiliates. The standard must be adopted using a modified retrospective method. The Company is evaluating the impact of this standard on its Consolidated Financial Statements. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows - Classification of Certain Cash Receipts and Cash Payments, which clarifies how cash receipts and cash payments are classified in the statement of cash flows. The standard is effective for interim and annual periods beginning after December 15, 2017 and must be adopted using a full retrospective method. The Company does not expect the adoption of this standard to have a significant impact on its Consolidated Financial Statements. In January 2017, the FASB issued ASU 2017-01, Clarifying the Definition of a Business, which provides guidance on evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The standard is effective for interim and annual periods beginning after December 15, 2017. The Company will apply the standard prospectively upon adoption. The impact of this standard on the Company’s Consolidated Financial Statements will depend on acquisitions (or disposals) of assets or businesses by the Company in periods following adoption. In January 2017, the FASB issued ASU 2017-04, Intangibles - Goodwill and Other: Simplifying the Accounting for Goodwill Impairment. Under the new standard, a goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value. The standard is effective for interim and annual periods beginning after December 15, 2019. The Company will apply the standard prospectively upon adoption. The Company is evaluating the impact of this standard on its Consolidated Financial Statements. In May 2017, the FASB issued ASU 2017-09, Compensation - Stock Compensation, which simplifies modification accounting related to share-based arrangements. Under the new standard, modification assessments will not be required if fair value, vesting conditions and classification would be unaffected by a modification. The standard is effective for interim and annual periods beginning after December 15, 2017. The Company will apply the standard prospectively upon adoption. The Company does not expect the adoption of this standard to have a significant impact on its Consolidated Financial Statements.
Investments in Affiliates and Affiliate Sponsored Investments Products	Investments in Affiliates The Company’s Affiliates are consolidated or accounted for under the equity method, depending upon the underlying structure of and relationship with each Affiliate. A limited number of the Company’s Affiliates are considered voting rights entities (“VREs”) because the total equity investment at risk is sufficient to enable the entities to finance their respective activities independently and each entity’s equity holders have the right to receive residual returns, the obligation to absorb losses and the right to direct the activities of the entity that most significantly impact its economic performance. Most of the Company’s Affiliates considered VREs are accounted for under the equity method because the Company lacks control, but is deemed to have significant influence. Substantially all of the Company’s Affiliates are considered variable interest entities (“VIEs”) because they are structured as partnerships (or similar entities) and the limited partners lack substantive kick-out or substantive participation rights over the general partner. The Company consolidates a VIE when it is the primary beneficiary of the entity, which is defined as having the power to direct the activities that most significantly impact the VIE’s economic performance and the right to receive benefits from or the obligation to absorb losses of the entity that could potentially be significant to the VIE. The Company applies the equity method of accounting to a VIE when it is not the primary beneficiary, but is deemed to have significant influence. Affiliate Sponsored Investment Products The Company’s consolidated Affiliates sponsor various investment products for which they also act as the investment advisor. These investment products are primarily owned by third-party investors; however, certain products are funded with general partner and seed capital investments from the Company and its Affiliates. Third-party investors are generally entitled to substantially all of the economics of these products. Certain of the Company’s Affiliate sponsored investment products are considered VIEs because they are structured as partnerships (or similar entities) and the limited partners lack substantive kick-out or substantive participation rights over the general partner. The Company's Affiliates’ involvement with sponsored investment products is generally limited to that of a service provider, and their seed capital investments, if any, represent an insignificant interest in the relevant investment products’ net assets. The Company’s and its consolidated Affiliates’ exposure to risk in these entities is generally limited to any capital contribution made or required to be made and any earned but uncollected management and performance fees. As a result, in most cases these VIEs are not consolidated and are accounted for under the equity method because neither the Company nor its Affiliates are deemed to be the primary beneficiary.
Fair Value Measurement	The following are descriptions of the significant financial assets and liabilities measured at fair value and the fair value methodologies used. Cash equivalents consist primarily of highly liquid investments in daily redeeming money market funds, without enacted liquidity fees or redemption gates that are valued at net asset value (“NAV”). Investments in marketable securities consist primarily of investments in publicly traded securities and funds advised by Affiliates that are valued at NAV. Publicly traded securities valued using unadjusted quoted market prices for identical instruments in active markets are classified as level 1. Publicly traded securities valued using quoted prices for similar instruments in active markets or quoted prices for identical or similar instruments in markets that are not active are classified as level 2. Investments in funds advised by Affiliates that are valued at NAV are classified as level 1. Contingent payment arrangements represent the present value of the expected future settlement of contingent payment arrangements related to the Company’s investments in consolidated Affiliates. The significant unobservable inputs that are used in the fair value measurement of these obligations are growth and discount rates. Increases in the growth rate result in a higher obligation while increases in the discount rate result in a lower obligation. Affiliate equity obligations include agreements to repurchase Affiliate equity. The significant unobservable inputs that are used in the fair value measurement of the agreements to repurchase Affiliate equity are growth and discount rates. Increases in the growth rate result in a higher obligation while increases in the discount rate result in a lower obligation. Foreign currency forward contracts use model-derived valuations in which all significant inputs are observable in active markets to determine fair value. It is the Company’s policy to value financial assets or liabilities transferred as of the beginning of the period in which the transfer occurs.

Investments in Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2017

Marketable Securities [Abstract]

Schedule of Available-For-Sale and Trading Securities

The following is a summary of the cost, gross unrealized gains and losses and fair value of investments classified as available-for-sale and trading:



	Available-for-Sale					Trading
	December 31, 2016			September 30, 2017		December 31, 2016			September 30, 2017
Cost	$	66.1		$	30.5	$	34.4		$	44.2
Unrealized gains	17.6			10.8		6.6			8.5
Unrealized losses	(1.8		)	—		(0.5		)	(1.6		)
Fair Value	$	81.9		$	41.3	$	40.5		$	51.1

Investments in Affiliates and Affiliate Sponsored Investments Products (Tables)

9 Months Ended

Sep. 30, 2017

Variable Interest Entities

Schedule of Unconsolidated Assets and Liabilities of Equity Method Investments and Company's Risk of Loss

The unconsolidated assets, net of liabilities and non-controlling interests of equity method Affiliates considered VIEs, and the Company’s maximum risk of loss were as follows:



	December 31, 2016				September 30, 2017
	Unconsolidated VIE Net Assets		Carrying Value and Maximum Exposure to Loss		Unconsolidated VIE Net Assets		Carrying Value and Maximum Exposure to Loss
Affiliates accounted for under the equity method	$	1,047.6	$	2,846.8	$	1,019.4	$	2,749.7

The net assets of Affiliate sponsored investment products that were considered VIEs accounted for under the equity method and the Company’s maximum risk of loss were as follows:



	December 31, 2016				September 30, 2017
	Unconsolidated VIE Net Assets		Carrying Value and Maximum Exposure to Loss		Unconsolidated VIE Net Assets		Carrying Value and Maximum Exposure to Loss
Affiliate sponsored investment products	$	1,756.6	$	9.4	$	1,961.5	$	9.9

- Definition

Tabular disclosure of the significant judgments and assumptions made in determining whether a variable interest (as defined) held by the entity requires the variable interest entity (VIE) (as defined) to be consolidated and (or) disclose information about its involvement with the VIE, individually or in aggregate (as applicable); the nature of restrictions, if any, on the consolidated VIE's assets and on the settlement of its liabilities reported by an entity in its statement of financial position, including the carrying amounts of such assets and liabilities; the nature of, and changes in, the risks associated with involvement in the VIE; how involvement with the VIE affects the entity's financial position, financial performance, and cash flows; the lack of recourse if creditors (or beneficial interest holders) of the consolidated VIE have no recourse to the general credit of the primary beneficiary (if applicable); the terms of arrangements, giving consideration to both explicit arrangements and implicit variable interests, if any, that could require the entity to provide financial support to the VIE, including events or circumstances that could expose the entity to a loss; the methodology used by the entity for determining whether or not it is the primary beneficiary of the variable interest entity; the significant factors considered and judgments made in determining that the power to direct the activities of a VIE that most significantly impact the VIE's economic performance are shared (as defined); the carrying amounts and classification of assets and liabilities of the VIE included in the statement of financial position; the entity's maximum exposure to loss, if any, as a result of its involvement with the VIE, including how the maximum exposure is determined and significant sources of the entity's exposure to the VIE; a comparison of the carrying amounts of the assets and liabilities and the entity's maximum exposure to loss; information about any liquidity arrangements, guarantees, and (or) other commitments by third parties that may affect the fair value or risk of the entity's variable interest in the VIE; whether or not the entity has provided financial support or other support (explicitly or implicitly) to the VIE that it was not previously contractually required to provide or whether the entity intends to provide that support, including the type and amount of the support and the primary reasons for providing the support; and supplemental information the entity determines necessary to provide.

+ References + Details

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2017

Fair Value Disclosures [Abstract]

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

The following tables summarize the Company’s financial assets and liabilities that are measured at fair value on a recurring basis:



			Fair Value Measurements
	December 31, 2016		Fair Value Measurements
	December 31, 2016		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)
Financial Assets
Cash equivalents	$	64.1	$	64.1	$	—	$	—
Investments in marketable securities⁽¹⁾
Trading securities	40.5		40.5		—		—
Available-for-sale securities	81.9		81.9		—		—
Other investments	3.4		3.4		—		—
Foreign currency forward contracts⁽²⁾	0.6		—		0.6		—
Financial Liabilities⁽²⁾
Contingent payment arrangements	$	8.6	$	—	$	—	$	8.6
Affiliate equity obligations	12.1		—		—		12.1
Foreign currency forward contracts	0.5		—		0.5		—



			Fair Value Measurements
	September 30, 2017		Fair Value Measurements
	September 30, 2017		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)
Financial Assets
Cash equivalents	$	35.1	$	35.1	$	—	$	—
Investments in marketable securities⁽¹⁾
Trading securities	51.1		51.1		—		—
Available-for-sale securities	41.3		41.3		—		—
Foreign currency forward contracts⁽²⁾	0.7		—		0.7		—
Financial Liabilities⁽²⁾
Contingent payment arrangements	$	8.1	$	—	$	—	$	8.1
Affiliate equity obligations	45.7		—		—		45.7
Foreign currency forward contracts	1.0		—		1.0		—

__________________________


⁽¹⁾	Principally investments in equity securities.


⁽²⁾	Amounts are presented within Other assets or Other liabilities.

Schedule of Changes in Level 3 Assets and Liabilities

The following tables present the changes in level 3 liabilities:



	For the Three Months Ended September 30,
	2016						2017
	Contingent Payment Arrangements			Affiliate Equity Obligations			Contingent Payment Arrangements			Affiliate Equity Obligations
Balance, beginning of period	$	8.0		$	27.0		$	7.8		$	70.7
Net realized and unrealized (gains) losses	0.2		⁽¹⁾	0.1			0.3		⁽¹⁾	(0.2		)
Purchases and issuances	—			8.4			—			11.1
Settlements and reductions	—			(8.8		)	—			(35.9		)
Balance, end of period	$	8.2		$	26.7		$	8.1		$	45.7

Net change in unrealized (gains) losses relating to instruments still held at the reporting date	$	0.2	⁽¹⁾	$	—		$	0.3	⁽¹⁾	$	—



	For the Nine Months Ended September 30,
	2016							2017
	Contingent Payment Arrangements				Affiliate Equity Obligations			Contingent Payment Arrangements				Affiliate Equity Obligations
Balance, beginning of period	$	10.2			$	62.3		$	8.6			$	12.1
Net realized and unrealized (gains) losses	(2.0		)	⁽¹⁾	0.1			2.3			⁽¹⁾	(0.2		)
Purchases and issuances	—				48.2			—				161.5
Settlements and reductions	—				(83.9		)	(2.8		)		(127.7		)
Balance, end of period	$	8.2			$	26.7		$	8.1			$	45.7

Net change in unrealized (gains) losses relating to instruments still held at the reporting date	$	(2.0	)	⁽¹⁾	$	—		2.3			⁽¹⁾	$	—

___________________________


⁽¹⁾	Accretion and changes in the expected value of the Company’s contingent payment arrangements are recorded in Imputed interest expense and contingent payment arrangements.

Schedule of Quantitative Information used in Valuing Level 3 Liabilities

The following table presents certain quantitative information about the significant unobservable inputs used in valuing the Company’s level 3 financial liabilities:



	Quantitative Information About Level 3 Fair Value Measurements
	Valuation Techniques	Unobservable Input	Fair Value at December 31, 2016		Range at December 31, 2016	Fair Value at September 30, 2017		Range at September 30, 2017
Contingent payment arrangements	Discounted cash flow	Growth rates	$	8.6	3% - 8%	$	8.1	8% - 9%
		Discount rates			14% - 15%			14% - 15%
Affiliate equity obligations	Discounted cash flow	Growth rates	12.1		4% - 10%	45.7		5% - 9%
		Discount rates			15% - 16%			12% - 16%

Summary of Investments in Certain Entities that Calculate Net Asset Value

The following table summarizes the nature of the Company’s investments, unfunded commitments and any related liquidity restrictions or other factors that may impact the ultimate value realized:



	December 31, 2016				September 30, 2017
Category of Investment	Fair Value		Unfunded Commitments		Fair Value		Unfunded Commitments
Private equity funds⁽¹⁾	$	137.8	$	92.2	$	151.9	$	94.9
Other funds⁽²⁾	9.7		—		8.6		—
Other investments⁽³⁾	$	147.5	$	92.2	$	160.5	$	94.9

___________________________


⁽¹⁾	The Company uses NAV as a practical expedient one quarter in arrears (adjusted for current period calls and distributions) to determine the fair value. These funds primarily invest in a broad range of private equity funds, as well as making direct investments. Distributions will be received as the underlying assets are liquidated over the life of the funds, which is generally up to 15 years.


⁽²⁾	These are multi-disciplinary funds that invest across various asset classes and strategies, including long/short equity, credit and real estate. Investments are generally redeemable on a daily, monthly or quarterly basis.


⁽³⁾	Fair value attributable to the controlling interest was $59.9 million and $72.8 million as of December 31, 2016 and September 30, 2017, respectively.

Summary of Financial Assets and Liabilities Not Carried at Fair Value

The following table summarizes the Company’s other financial liabilities not carried at fair value:



	December 31, 2016				September 30, 2017
	Carrying Value		Fair Value		Carrying Value		Fair Value		Fair Value Hierarchy
Senior notes	$	945.1	$	936.0	$	745.5	$	779.6	Level 2
Convertible securities	307.5		466.9		309.3		527.8		Level 2

Goodwill and Acquired Client Relationships (Tables)

9 Months Ended

Sep. 30, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Changes in Goodwill

The following tables present the changes in the Company’s consolidated Affiliates’ Goodwill and components of Acquired client relationships (net):



	Goodwill
	Total
Balance, as of December 31, 2016	$	2,628.1
Foreign currency translation	33.7
Balance, as of September 30, 2017	$	2,661.8

Schedule of Changes in the Components of Acquired Client Relationships



	Acquired Client Relationships
	Definite-lived								Indefinite-lived		Total
	Gross Book Value		Accumulated Amortization			Net Book Value			Net Book Value		Net Book Value
Balance, as of December 31, 2016	$	1,290.0	$	(788.1	)	$	501.9		$	995.5	$	1,497.4
Intangible amortization and impairments	—		(65.1		)	(65.1		)	—		(65.1		)
Foreign currency translation	5.0		—			5.0			29.9		34.9
Balance, as of September 30, 2017	$	1,295.0	$	(853.2	)	$	441.8		$	1,025.4	$	1,467.2

Equity Method Investments in Affiliates (Tables)

9 Months Ended

Sep. 30, 2017

Equity Method Investments and Joint Ventures [Abstract]

Schedule of Aggregate Purchase Price Allocation of Equity Method Investments

The aggregate purchase price allocation for the 2016 investments was as follows:



	Total
Consideration paid	$	1,362.3

Definite-lived acquired client relationships	$	560.8
Indefinite-lived acquired client relationships	36.9
Tangible assets	2.0
Deferred tax liability	(91.8		)
Goodwill	854.4
	$	1,362.3

Schedule of Changes in Equity Method Investments in Affiliates

The following table presents the change in Equity method investments in Affiliates:



	Total
Balance, as of December 31, 2016	$	3,368.3
Equity method earnings	303.3
Equity method intangible amortization	(71.7		)
Distributions of earnings from equity method investments	(368.0		)
Investments	29.8
Foreign currency translation	32.1
Other	(3.0		)
Balance, as of September 30, 2017	$	3,290.8

Share-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of Share-Based Compensation

The following is a summary of share-based compensation expense:



	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2016		2017		2016		2017
Share-based compensation	$	10.7	$	10.3	$	30.7	$	30.0
Tax benefit	4.1		4.0		11.8		11.5

Schedule of Company Stock Option Transactions

The following table summarizes transactions in the Company’s stock options:



	Stock Options		Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (years)
Unexercised options outstanding - December 31, 2016	1.4		$	108.53
Options granted	0.0		168.60
Options exercised	(0.6	)	96.86
Options forfeited	(0.1	)	140.26
Unexercised options outstanding - September 30, 2017	0.7		118.35		3.5
Exercisable at September 30, 2017	0.3		108.55		1.5

Schedule of Fair Value of Options Granted and Assumptions

For the nine months ended September 30, 2016 and 2017, the weighted average fair values of options granted were $39.02 and $48.05, per option, respectively, based on the weighted-average grant date assumptions stated below.



	For the Nine Months Ended September 30,
	2016		2017
Dividend yield	—		0.5	%
Expected volatility	30.7	%	28.0	%
Risk-free interest rate	1.6	%	2.1	%
Expected life of options (in years)	5.7		5.7
Forfeiture rate	—		—

Schedule of Company Restricted Stock Unit Transactions

The following table summarizes transactions in the Company’s restricted stock units:



	Restricted Stock Units		Weighted Average Grant Date Value
Unvested units - December 31, 2016	0.6		$	168.84
Units granted	0.2		153.09
Units vested	(0.2	)	167.72
Units forfeited	(0.0	)	170.52
Unvested units - September 30, 2017	0.6		162.97

Redeemable Non-Controlling Interests (Tables)

9 Months Ended

Sep. 30, 2017

Noncontrolling Interest [Abstract]

Schedule of Changes in Redeemable Non-Controlling Interests

The following table presents the changes in Redeemable non-controlling interests:



	Redeemable Non-controlling interests
Balance, as of December 31, 2016	$	673.5
Changes attributable to consolidated products	9.5
Repurchases of redeemable Affiliate equity	(151.6		)
Transfers from non-controlling interests	56.8
Changes in redemption value	216.4
Balance, as of September 30, 2017	$	804.6

Affiliate Equity (Tables)

9 Months Ended

Sep. 30, 2017

Affiliate Equity [Abstract]

Summary of Affiliate Equity Compensation

The following is a summary of Affiliate equity expense:



	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2016		2017		2016		2017
Controlling interest	$	3.2	$	2.3	$	7.7	$	9.4
Non-controlling interests	18.5		7.7		27.2		29.2
Total	$	21.7	$	10.0	$	34.9	$	38.6

Summary of Affiliate Equity Unrecognized Compensation Expense [Table Text Block]

The following is a summary of unrecognized Affiliate equity expense:



	Controlling Interest		Remaining Life	Non-controlling Interests		Remaining Life
December 31, 2016	$	31.3	4 years	$	70.7	5 years
September 30, 2017	33.0		4 years	82.5		5 years

Schedule of Changes in the Company's Interest in its Affiliates on the Controlling Interest's Equity



	For the Three Months Ended September 30,						For the Nine Months Ended September 30,
	2016			2017			2016			2017
Net income (controlling interest)	$	110.2		$	125.4		$	322.5		$	374.2
Increase / (decrease) in controlling interest paid-in capital from purchases and sales of Affiliate equity issuances	5.3			(0.3		)	1.9			(0.6		)
Decrease in controlling interest paid-in capital related to Affiliate equity repurchases	(2.1		)	(12.7		)	(23.4		)	(81.8		)
Net income attributable to controlling interest and transfers from Non-controlling interests	$	113.4		$	112.4		$	301.0		$	291.8

Income Taxes (Tables)

9 Months Ended

Sep. 30, 2017

Income Tax Disclosure [Abstract]

Schedule of Income Tax Provisions by Controlling and Noncontrolling Interests

The consolidated income tax provision includes taxes attributable to the controlling interest and, to a lesser extent, taxes attributable to the non-controlling interests as follows:



	For the Three Months Ended September 30,						For the Nine Months Ended September 30,
	2016			2017			2016			2017
Controlling interest:
Current tax	$	29.5		$	39.6		$	84.2		$	102.0
Intangible-related deferred taxes	19.5			22.9			63.0			61.8
Other deferred taxes	1.1			1.6			8.4			18.7
Total controlling interest	50.1			64.1			155.6			182.5
Non-controlling interests:
Current tax	$	1.5		$	2.1		$	5.7		$	5.9
Deferred taxes	(1.3		)	(0.1		)	(1.6		)	(0.2		)
Total non-controlling interests	0.2			2.0			4.1			5.7
Provision for income taxes	$	50.3		$	66.1		$	159.7		$	188.2
Income before income taxes (controlling interest)	$	160.3		$	189.5		$	478.1		$	556.7
Effective tax rate attributable to controlling interest⁽¹⁾	31.3		%	33.8		%	32.5		%	32.8		%

__________________________


⁽¹⁾	Taxes attributable to the controlling interest divided by Income before income taxes (controlling interest).

Earnings Per Share (Tables)

9 Months Ended

Sep. 30, 2017

Earnings Per Share [Abstract]

Schedule of Basic and Diluted Earnings Per Share

The following is a reconciliation of the numerator and denominator used in the calculation of basic and diluted earnings per share available to common stockholders.



	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2016		2017		2016		2017
Numerator
Net income (controlling interest)	$	110.2	$	125.4	$	322.5	$	374.2
Interest expense on convertible securities, net of taxes	3.9		3.9		11.6		11.6
Net income (controlling interest), as adjusted	$	114.1	$	129.3	$	334.1	$	385.8
Denominator
Average shares outstanding (basic)	53.9		55.8		53.9		56.3
Effect of dilutive instruments:
Stock options and restricted stock units	0.5		0.3		0.5		0.3
Junior convertible securities	2.2		2.2		2.2		2.2
Average shares outstanding (diluted)	56.6		58.3		56.6		58.8

Schedule of Shares Excluded from Calculation of Basic and Diluted Earnings Per Share

Average shares outstanding (diluted) in the table above exclude share awards that have not satisfied performance conditions and the anti-dilutive effect of the following shares:



	For the Three Months Ended September 30,		For the Nine Months Ended September 30,
	2016	2017	2016	2017
Stock options and restricted stock units	0.5	0.0	0.7	0.1
Shares subject to forward sale agreement	2.0	—	2.0	—

Comprehensive Income (Tables)

9 Months Ended

Sep. 30, 2017

Other Comprehensive Income (Loss), Net of Tax [Abstract]

Summary of the Tax Effects Allocated to Each Component of Other Comprehensive Income

The following tables show the tax effects allocated to each component of Other comprehensive income (loss):



	For the Three Months Ended September 30,
	2016									2017
	Pre-Tax			Tax Benefit (Expense)			Net of Tax			Pre-Tax			Tax Benefit (Expense)			Net of Tax
Foreign currency translation adjustment	$	(16.8	)	$	—		$	(16.8	)	$	53.0		$	—		$	53.0
Change in net realized and unrealized gain (loss) on derivative securities	0.1			(0.0		)	0.1			0.2			(0.1		)	0.1
Change in net unrealized gain (loss) on investment securities	5.8			(1.8		)	4.0			(6.8		)	2.5			(4.3		)
Other comprehensive income (loss)	$	(10.9	)	$	(1.8	)	$	(12.7	)	$	46.4		$	2.4		$	48.8



	For the Nine Months Ended September 30,
	2016									2017
	Pre-Tax			Tax Benefit (Expense)			Net of Tax			Pre-Tax			Tax Benefit (Expense)			Net of Tax
Foreign currency translation adjustment	$	(72.7	)	$	—		$	(72.7	)	$	92.1		$	—		$	92.1
Change in net realized and unrealized gain (loss) on derivative securities	(0.6		)	(0.1		)	(0.7		)	(0.7		)	(0.1		)	(0.8		)
Change in net unrealized gain (loss) on investment securities	(34.6		)	13.8			(20.8		)	(6.6		)	3.2			(3.4		)
Other comprehensive income (loss)	$	(107.9	)	$	13.7		$	(94.2	)	$	84.8		$	3.1		$	87.9

Schedule of Components of Accumulated Other Comprehensive Income

The components of accumulated other comprehensive income (loss), net of taxes, were as follows:



	Foreign Currency Translation Adjustment			Realized and Unrealized Gains (Losses) on Derivative Securities			Unrealized Gains (Losses) on Investment Securities ⁽¹⁾			Total
Balance, as of December 31, 2016	$	(213.9	)	$	0.4		$	9.8		$	(203.7	)
Other comprehensive gain (loss) before reclassifications	92.1			(0.4		)	13.8			105.5
Amounts reclassified	—			(0.4		)	(17.2		)	(17.6		)
Net other comprehensive gain (loss)	92.1			(0.8		)	(3.4		)	87.9
Balance, as of September 30, 2017	$	(121.8	)	$	(0.4	)	$	6.4		$	(115.8	)

__________________________


⁽¹⁾	See Note 3 for amounts reclassified from Other comprehensive income (loss).

Investments in Marketable Securities - Schedule of Available-For-Sale and Trading Securities (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Available-for-Sale
Cost	$ 30.5		$ 66.1
Unrealized gains	10.8		17.6
Unrealized losses	0.0		(1.8)
Fair Value	41.3		81.9
Trading
Cost			$ 44.2	$ 34.4
Unrealized gains	8.5	$ 6.6
Unrealized losses	(1.6)	(0.5)
Fair Value	$ 51.1	$ 40.5

Investments in Marketable Securities - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Investments in marketable securities	$ 92.4		$ 92.4		$ 122.4
Proceeds from sale of available-for-sale securities	15.4	$ 12.6	58.7	$ 47.0
Realized gains on available-for-sale securities	7.4	$ 6.2	19.2	$ 15.4
Proceeds from sale of trading securities	8.2		23.2
Realized gains on trading securities	$ 1.7		$ 5.0

Investments in Affiliates and Affiliate Sponsored Investments Products - Affiliated Accounted For Under Equity Method (Details) - Affiliates accounted for under the equity method - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Variable Interest Entities
Unconsolidated VIE Net Assets	$ 1,019.4	$ 1,047.6
Carrying Value and Maximum Exposure to Loss	$ 2,749.7	$ 2,846.8

Investments in Affiliates and Affiliate Sponsored Investments Products - Affiliated Sponsored Investment Products (Details) - Affiliate sponsored investment products - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Variable Interest Entities
Unconsolidated VIE Net Assets	$ 1,961.5	$ 1,756.6
Carrying Value and Maximum Exposure to Loss	$ 9.9	$ 9.4

Commitments and Contingencies (Details) - USD ($)	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Commitments and Contingencies
Co-investment commitments in partnership		$ 94,900,000
Consolidated Affiliates
Commitments and Contingencies
Contingent liability		21,700,000
Expected payments of contingent liability		8,900,000
Present value of expected payments of contingent liabilities		8,100,000
Consolidated Affiliates \| Scenario, Forecast
Commitments and Contingencies
Expected payments of contingent liability	$ 1,600,000
Equity Method Investee
Commitments and Contingencies
Contingent liability		$ 170,000,000
Equity Method Investee \| Scenario, Forecast
Commitments and Contingencies
Expected payments of contingent liability	$ 0
Third Avenue Focused Credit Fund \| Affiliated Entity \| Third Avenue
Commitments and Contingencies
Loss contingency reserve			$ 15,000,000

Senior Notes (Details) - Senior Notes - Senior Notes 6.375% due 2042 $ in Millions	3 Months Ended
	Sep. 30, 2017 USD ($)
Long-term debt
Debt redeemed	$ 200.0
Interest rate	6.375%
Debt, redemption price as a percentage of principal amount	100.00%

Fair Value Measurements - Assets and Liabilities Measured on a Recurring Basis (Details) - USD ($)
$ in Millions

Sep. 30, 2017

Dec. 31, 2016

Sep. 30, 2016

Investments in marketable securities

Trading securities

$ 51.1

$ 40.5

Fair Value Measured On A Recurring Basis

Financial Assets

Cash equivalents

35.1

$ 64.1

Investments in marketable securities

Trading securities

^[1]

51.1

40.5

Available-for-sale securities

^[1]

41.3

81.9

Other investments

3.4

Foreign currency forward contracts

^[2]

0.7

0.6

Financial Liabilities

Contingent payment arrangements

^[2]

8.1

8.6

Affiliate equity obligations

^[2]

45.7

12.1

Foreign currency forward contracts

^[2]

1.0

0.5

Fair Value Measured On A Recurring Basis | Quoted Prices in Active Markets for Identical Assets (Level 1)

Financial Assets

Cash equivalents

35.1

64.1

Investments in marketable securities

Trading securities

^[1]

51.1

40.5

Available-for-sale securities

^[1]

41.3

81.9

Other investments

3.4

Foreign currency forward contracts

^[2]

0.0

Financial Liabilities

Contingent payment arrangements

^[2]

0.0

Affiliate equity obligations

^[2]

0.0

Foreign currency forward contracts

^[2]

0.0

Fair Value Measured On A Recurring Basis | Significant Other Observable Inputs (Level 2)

Financial Assets

Cash equivalents

0.0

Investments in marketable securities

Trading securities

^[1]

0.0

Available-for-sale securities

^[1]

0.0

Other investments

0.0

Foreign currency forward contracts

^[2]

0.7

0.6

Financial Liabilities

Contingent payment arrangements

^[2]

0.0

Affiliate equity obligations

^[2]

0.0

Foreign currency forward contracts

^[2]

1.0

0.5

Fair Value Measured On A Recurring Basis | Significant Other Unobservable Inputs (Level 3)

Financial Assets

Cash equivalents

0.0

Investments in marketable securities

Trading securities

^[1]

0.0

Available-for-sale securities

^[1]

0.0

Other investments

0.0

Foreign currency forward contracts

^[2]

0.0

Financial Liabilities

Contingent payment arrangements

^[2]

8.1

8.6

Affiliate equity obligations

^[2]

45.7

12.1

Foreign currency forward contracts

^[2]

$ 0.0

[1]	Principally investments in equity securities.
[2]	Amounts are presented within Other assets or Other liabilities.

Fair Value Measurements - Changes in Level 3 Assets and Liabilities (Details) - USD ($)
$ in Millions

3 Months Ended

9 Months Ended

Sep. 30, 2017

Sep. 30, 2016

Sep. 30, 2017

Sep. 30, 2016

Contingent Payment Arrangements

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]

Balance, beginning of period

$ 7.8

$ 8.0

$ 8.6

$ 10.2

Net realized and unrealized (gains) losses

^[1]

0.3

0.2

2.3

(2.0)

Purchases and issuances

0.0

Settlements and reductions

0.0

(2.8)

0.0

Balance, end of period

8.1

8.2

8.1

8.2

Net change in unrealized (gains) losses relating to instruments still held at the reporting date

^[1]

0.3

0.2

2.3

(2.0)

Affiliate Equity Obligations

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]

Balance, beginning of period

70.7

27.0

12.1

62.3

Net realized and unrealized (gains) losses

^[1]

(0.2)

0.1

(0.2)

0.1

Purchases and issuances

11.1

8.4

161.5

48.2

Settlements and reductions

(35.9)

(8.8)

(127.7)

(83.9)

Balance, end of period

45.7

26.7

45.7

26.7

Net change in unrealized (gains) losses relating to instruments still held at the reporting date

$ 0.0

[1]	Accretion and changes in the expected value of the Company’s contingent payment arrangements are recorded in Imputed interest expense and contingent payment arrangements.

Fair Value Measurements - Quantitative Information used in Valuing Level 3 Liabilities (Details) - Discounted Cash Flow - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Contingent Payment Arrangements
Quantitative information for Level 3 Fair Value Measurements Liabilities
Fair value liabilities	$ 8.1	$ 8.6
Contingent Payment Arrangements \| Minimum
Quantitative information for Level 3 Fair Value Measurements Liabilities
Growth rate (as a percent)	8.00%	3.00%
Discount rate (as a percent)	14.00%	14.00%
Contingent Payment Arrangements \| Maximum
Quantitative information for Level 3 Fair Value Measurements Liabilities
Growth rate (as a percent)	9.00%	8.00%
Discount rate (as a percent)	15.00%	15.00%
Affiliate Equity Obligations
Quantitative information for Level 3 Fair Value Measurements Liabilities
Fair value liabilities	$ 45.7	$ 12.1
Affiliate Equity Obligations \| Minimum
Quantitative information for Level 3 Fair Value Measurements Liabilities
Growth rate (as a percent)	5.00%	4.00%
Discount rate (as a percent)	12.00%	15.00%
Affiliate Equity Obligations \| Maximum
Quantitative information for Level 3 Fair Value Measurements Liabilities
Growth rate (as a percent)	9.00%	10.00%
Discount rate (as a percent)	16.00%	16.00%

Fair Value Measurements - Investments Measured at Net Asset Value as Practical Expedient (Details) - USD ($)
$ in Millions

9 Months Ended

Sep. 30, 2017

Dec. 31, 2016

NAV of investments at fair value

Life of funds (in years)

15 years

Other Investments

NAV of investments at fair value

Fair Value

^[1]

$ 160.5

$ 147.5

Unfunded Commitments

94.9

92.2

Other Investments | Controlling Interest

NAV of investments at fair value

Fair Value

59.9

72.8

Private Equity Funds

NAV of investments at fair value

Fair Value

^[2]

151.9

137.8

Unfunded Commitments

^[2]

94.9

92.2

Other Funds

NAV of investments at fair value

Fair Value

^[3]

8.6

9.7

Unfunded Commitments

^[3]

$ 0.0

[1]	Fair value attributable to the controlling interest was $59.9 million and $72.8 million as of December 31, 2016 and September 30, 2017, respectively.
[2]	The Company uses NAV as a practical expedient one quarter in arrears (adjusted for current period calls and distributions) to determine the fair value. These funds primarily invest in a broad range of private equity funds, as well as making direct investments. Distributions will be received as the underlying assets are liquidated over the life of the funds, which is generally up to 15 years.
[3]	These are multi-disciplinary funds that invest across various asset classes and strategies, including long/short equity, credit and real estate. Investments are generally redeemable on a daily, monthly or quarterly basis.

Fair Value Measurements - Financial Assets and Liabilities Not Carried at Fair Value (Details) - Level 2 - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Senior notes	$ 745.5	$ 945.1
Convertible securities	309.3	307.5
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Senior notes	779.6	936.0
Convertible securities	$ 527.8	$ 466.9

Goodwill and Acquired Client Relationships - Schedule of Changes in Goodwill (Details) $ in Millions	9 Months Ended
	Sep. 30, 2017 USD ($)
Goodwill [Roll Forward]
Balance, as of December 31, 2016	$ 2,628.1
Foreign currency translation	33.7
Balance, as of September 30, 2017	$ 2,661.8

Goodwill and Acquired Client Relationships - Schedule of Changes in the Components of Acquired Client Relationships (Details) $ in Millions	9 Months Ended
	Sep. 30, 2017 USD ($)
Total
Beginning balance, net book value	$ 1,497.4
Ending balance, net book value	1,467.2
Acquired Client Relationships
Definite-lived
Beginning balance, gross book value	1,290.0
Beginning balance, accumulated amortization	(788.1)
Beginning balance, net book value	501.9
Amortization and impairments	(65.1)
Foreign currency translation	5.0
Ending balance, gross book value	1,295.0
Ending balance, accumulated amortization	(853.2)
Ending balance, net book value	441.8
Indefinite-lived
Beginning balance, net book value	995.5
Intangible amortization and impairments	0.0
Foreign currency translation	29.9
Ending balance, net book value	1,025.4
Total
Beginning balance, net book value	1,497.4
Amortization and impairments	(65.1)
Foreign currency translation	34.9
Ending balance, net book value	$ 1,467.2

Goodwill and Acquired Client Relationships - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Intangible Assets
Goodwill impairments			$ 0
Amortization and impairment expenses of intangible assets	$ 21,200,000	$ 26,900,000	$ 65,100,000	$ 82,200,000
Acquired Client Relationships
Intangible Assets
Weighted average life			12 years
Finite-Lived Intangible Assets, Net, Amortization Expense, Rolling Maturity [Abstract]
Finite-lived intangible, future amortization expense in 2017	85,000,000		$ 85,000,000
Finite-lived intangible, future amortization expense in 2018	85,000,000		85,000,000
Finite-lived intangible, future amortization expense in 2019	85,000,000		85,000,000
Finite-lived intangible, future amortization expense in 2020	50,000,000		50,000,000
Finite-lived intangible, future amortization expense in 2021	30,000,000		30,000,000
Acquired Client Relationships \| Intangible amortization and impairments
Intangible Assets
Amortization and impairment expenses of intangible assets	$ 21,200,000	$ 26,900,000	$ 65,100,000	$ 82,200,000

Equity Method Investments in Affiliates - Aggregate Purchase Price Allocation (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Deferred Tax Liability	$ (702.3)		$ (702.3)		$ (660.8)
Goodwill	2,661.8		2,661.8		2,628.1
Intangible amortization and impairments	21.2	$ 26.9	65.1	$ 82.2
Acquired Client Relationships
Schedule of Equity Method Investments [Line Items]
Definite-lived acquired client relationships	441.8		441.8		501.9
Indefinite-lived acquired client relationships	1,025.4		1,025.4		995.5
Equity Method Investee \| Acquired Client Relationships
Schedule of Equity Method Investments [Line Items]
Intangible amortization and impairments	$ 25.9	$ 14.0	$ 71.7	$ 43.0
Equity Method Investee \| 2016 New Seven Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Consideration paid					1,362.3
Tangible assets					2.0
Deferred Tax Liability					(91.8)
Goodwill					854.4
Equity Method Investments					1,362.3
Equity Method Investee \| 2016 New Seven Equity Method Investments \| Acquired Client Relationships
Schedule of Equity Method Investments [Line Items]
Definite-lived acquired client relationships					560.8
Indefinite-lived acquired client relationships					$ 36.9

Equity Method Investments in Affiliates - Change in Equity Method Investments (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Change in Equity Method Investments in Affiliates [Roll Forward]
Balance, as of December 31, 2016	$ 3,368.3
Distributions of earnings from equity method investments	(368.0)	$ (287.0)
Balance, as of September 30, 2017	3,290.8
Equity Method Investee
Change in Equity Method Investments in Affiliates [Roll Forward]
Balance, as of December 31, 2016	3,368.3
Equity method earnings	303.3
Equity method intangible amortization	(71.7)
Distributions of earnings from equity method investments	(368.0)
Investments	29.8
Foreign currency translation	32.1
Other	(3.0)
Balance, as of September 30, 2017	$ 3,290.8

Equity Method Investments in Affiliates - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Schedule of Equity Method Investments [Line Items]
Amortization expense during the period	$ 21.2	$ 26.9	$ 65.1	$ 82.2
Acquired Client Relationships
Schedule of Equity Method Investments [Line Items]
Weighted average client-acquired relationships			12 years
Finite-lived intangible, future amortization expense, next twelve months	85.0		$ 85.0
Finite-lived intangible, future amortization expense, year 2	85.0		85.0
Finite-lived intangible, future amortization expense, year 3	85.0		85.0
Finite-lived intangible, future amortization expense, year 4	50.0		50.0
Finite-lived intangible, future amortization expense, year 5	30.0		30.0
Equity Method Investee
Schedule of Equity Method Investments [Line Items]
Revenue from equity method investments	301.8	230.2	826.6	658.6
Net income from equity method investments	178.3	126.4	$ 471.3	361.0
Equity Method Investee \| Acquired Client Relationships
Schedule of Equity Method Investments [Line Items]
Weighted average client-acquired relationships			10 years
Amortization expense during the period	25.9	14.0	$ 71.7	43.0
Finite-lived intangible, future amortization expense, next twelve months	100.0		100.0
Finite-lived intangible, future amortization expense, year 2	100.0		100.0
Finite-lived intangible, future amortization expense, year 3	80.0		80.0
Finite-lived intangible, future amortization expense, year 4	80.0		80.0
Finite-lived intangible, future amortization expense, year 5	80.0		80.0
Systematica Investment LP and Baring Private Equity Asia \| Equity Method Investee \| Acquired Client Relationships
Schedule of Equity Method Investments [Line Items]
Amortization expense during the period	$ 15.5	$ 3.7	$ 33.9	$ 11.2

Related Party Transactions (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Related Party Transactions
Other liabilities	$ 178.3	$ 149.4
Non-controlling interests	776.8	806.9
Prior Owner \| Private Equity Investment Partnerships of Affiliate
Related Party Transactions
Other liabilities	64.1	67.8
Non-controlling interests	0.8	2.5
Affiliated Entity \| Other Liabilities
Related Party Transactions
Contingent payment arrangements liability	$ 8.1	$ 8.6

Share-Based Compensation - Summary of Share-Based Compensation (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-based compensation	$ 10.3	$ 10.7	$ 30.0	$ 30.7
Tax benefit	4.0	$ 4.1	11.5	$ 11.8
Compensation expense related to share-based compensation	$ 73.8		$ 73.8		$ 66.4
Weighted average period over which compensation expense will be recognized			3 years

Share-Based Compensation - Schedule of the Transactions of the Company's Stock Options (Details) - Stock Options shares in Millions	9 Months Ended
	Sep. 30, 2017 $ / shares shares
Stock Options
Unexercised options outstanding at the beginning of the period (in shares) \| shares	1.4
Options granted (in shares) \| shares	0.0
Options exercised (in shares) \| shares	(0.6)
Options forfeited (in shares) \| shares	(0.1)
Unexercised options outstanding at the end of the period (in shares) \| shares	0.7
Exercisable at the end of the period (in shares) \| shares	0.3
Weighted Average Exercise Price
Unexercised options outstanding at the beginning of the period (in dollars per share) \| $ / shares	$ 108.53
Options granted (in dollars per share) \| $ / shares	168.60
Options exercised (in dollars per share) \| $ / shares	96.86
Options forfeited (in dollars per share) \| $ / shares	140.26
Unexercised options outstanding at the end of the period (in dollars per share) \| $ / shares	118.35
Exercisable at the end of the period (in dollars per share) \| $ / shares	$ 108.55
Weighted Average Remaining Contractual Life
Unexercised options outstanding at the end of the period (in years)	3 years 6 months
Exercisable at the end of the period (in years)	1 year 6 months

Share-Based Compensation - Schedule of Fair Value Options Granted and Assumptions (Details) - Stock Options - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Share-based Compensation
Stock options granted, fair value	$ 0.8	$ 16.4
Stock options, expiration period (in years)	7 years
Stock options granted, weighted average fair value (in dollar per share)	$ 48.05	$ 39.02
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Dividend yield	0.50%	0.00%
Expected volatility	28.00%	30.70%
Risk-fee interest rate	2.10%	1.60%
Expected life of options (in years)	5 years 8 months 12 days	5 years 8 months 12 days
Forfeiture rate	0.00%	0.00%
Minimum
Share-based Compensation
Stock options, vesting period (in years)	3 years
Maximum
Share-based Compensation
Stock options, vesting period (in years)	4 years

Share-Based Compensation - Schedule of Company Restricted Stock Unit Transactions (Details) - Restricted Stock - USD ($) $ / shares in Units, shares in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Restricted Stock Units
Unvested units at the beginning of the period (in shares)	0.6
Units granted (in shares)	0.2
Units vested (in shares)	(0.2)
Units forfeited (in shares)	0.0
Unvested units at the end of the period (in shares)	0.6
Weighted Average Grant Date Value
Unvested units at the beginning of the period (in dollars per share)	$ 168.84
Units granted (in dollars per share)	153.09
Units vested (in dollars per share)	167.72
Units forfeited (in dollars per share)	170.52
Unvested units at the end of the period (in dollars per share)	$ 162.97
Restricted stocks granted, fair value	$ 36.7	$ 28.0
Minimum
Weighted Average Grant Date Value
Restricted stock, vesting period (in years)	3 years
Maximum
Weighted Average Grant Date Value
Restricted stock, vesting period (in years)	4 years

Redeemable Non-Controlling Interests (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Redeemable Noncontrolling Interest [Roll Forward]
Balance, as of December 31, 2016	$ 673.5
Changes attributable to consolidated products	9.5
Repurchases of redeemable Affiliate equity	(151.6)
Transfers from non-controlling interests	56.8	$ 38.3
Changes in redemption value	216.4
Balance, as of September 30, 2017	$ 804.6
Minimum
Noncontrolling Interest [Line Items]
Term of conditional right to put interest	5 years
Maximum
Noncontrolling Interest [Line Items]
Term of conditional right to put interest	15 years

Affiliated Equity - Additional Information (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Affiliate Equity [Line Items]
Distributions paid to affiliate partners	$ 266.8	$ 270.1
Payments to acquire interest in affiliates	121.3	82.1
Issuance of interest in affiliates	8.8	$ 11.8
Other Assets
Affiliate Equity [Line Items]
Due from affiliates	10.9		$ 22.9
Other Liabilities
Affiliate Equity [Line Items]
Due to affiliates	$ 45.7		$ 12.1

Affiliate Equity - Summary of Affiliate Recognized and Unrecognized Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Affiliate Equity [Line Items]
Affiliate equity expense	$ 10.0	$ 21.7	$ 38.6	$ 34.9
Non-controlling Interests
Affiliate Equity [Line Items]
Non-controlling interests	7.7	18.5	$ 29.2	27.2
Unrecognized Affiliate Equity Expense [Abstract]
Remaining Life (in years)			5 years		5 years
Non-Controlling Interest			$ 82.5		$ 70.7
Affiliated Entity
Affiliate Equity [Line Items]
Controlling interest	$ 2.3	$ 3.2	9.4	$ 7.7
Unrecognized Affiliate Equity Expense [Abstract]
Controlling Interest			$ 33.0		$ 31.3
Remaining Life (in years)			4 years		4 years

Affiliate Equity - Schedule of Changes in the Company's Interest in its Affiliates on the Controlling Interest's Equity (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Affiliate Equity [Abstract]
Net income (controlling interest)	$ 125.4	$ 110.2	$ 374.2	$ 322.5
Increase / (decrease) in controlling interest paid-in capital from purchases and sales of Affiliate equity issuances	(0.3)	5.3	(0.6)	1.9
Decrease in controlling interest paid-in capital related to Affiliate equity repurchases	(12.7)	(2.1)	(81.8)	(23.4)
Net income attributable to controlling interest and transfers (to) or from Non-controlling interests	$ 112.4	$ 113.4	$ 291.8	$ 301.0

Income Taxes - Schedule of Income Tax Provisions by Controlling and Noncontrolling Interests (Details) - USD ($)
$ in Millions

3 Months Ended

9 Months Ended

Sep. 30, 2017

Sep. 30, 2016

Sep. 30, 2017

Sep. 30, 2016

Income Tax Provision

Deferred taxes

$ 80.3

$ 69.8

Provision for income taxes

$ 66.1

$ 50.3

188.2

159.7

Non-controlling Interests

Income Tax Provision

Current tax

2.1

1.5

5.9

5.7

Deferred taxes

(0.1)

(1.3)

(0.2)

(1.6)

Provision for income taxes

2.0

0.2

5.7

4.1

Controlling Interest

Income Tax Provision

Current tax

39.6

29.5

102.0

84.2

Intangible-related deferred taxes

22.9

19.5

61.8

63.0

Other deferred taxes

1.6

1.1

18.7

8.4

Provision for income taxes

64.1

50.1

182.5

155.6

Income before income taxes (controlling interest)

$ 189.5

$ 160.3

$ 556.7

$ 478.1

Effective tax rate attributable to controlling interests

^[1]

33.80%

31.30%

32.80%

32.50%

[1]	Taxes attributable to the controlling interest divided by Income before income taxes (controlling interest).

Earnings Per Share - Schedule of Basic and Diluted Earnings Per Share (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator
Net income (controlling interest)	$ 125.4	$ 110.2	$ 374.2	$ 322.5
Interest expense on convertible securities, net of taxes	3.9	3.9	11.6	11.6
Net income (controlling interest), as adjusted	$ 129.3	$ 114.1	$ 385.8	$ 334.1
Denominator
Average shares outstanding—basic (in shares)	55.8	53.9	56.3	53.9
Effect of dilutive instruments:
Stock options and restricted stock (in shares)	0.3	0.5	0.3	0.5
Junior convertible securities (in shares)	2.2	2.2	2.2	2.2
Average shares outstanding—diluted (in shares)	58.3	56.6	58.8	56.6

Earnings Per Share - Schedule of Shares Excluded from Calculation of Basic and Diluted Earnings Per Share (Details) - shares shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Stock options and restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	0.0	0.5	0.1	0.7
Shares subject to forward sale agreement
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	0.0	2.0	0.0	2.0

Earnings Per Share - Additional Information (Details) - $ / shares shares in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017
Earnings Per Share [Abstract]
Number or shares repurchased during period (in shares)	0.4	1.7
Average price of shares repurchased during period (in dollars per share)	$ 175.68	$ 164.00

Comprehensive Income - Summary of the Tax Effects Allocated to Each Component of Other Comprehensive Income(Details) - USD ($)
$ in Millions

3 Months Ended

9 Months Ended

Sep. 30, 2017

Sep. 30, 2016

Sep. 30, 2017

Sep. 30, 2016

Accumulated Other Comprehensive Income (Loss)

Pre-Tax

$ 46.4

$ (10.9)

$ 84.8

$ (107.9)

Tax Benefit (Expense)

2.4

(1.8)

3.1

13.7

Other comprehensive income (loss)

48.8

(12.7)

87.9

(94.2)

Foreign Currency Translation Adjustment

Accumulated Other Comprehensive Income (Loss)

Pre-Tax

53.0

(16.8)

92.1

(72.7)

Tax Benefit (Expense)

0.0

Other comprehensive income (loss)

53.0

(16.8)

92.1

(72.7)

Change in net realized and unrealized gain (loss) on derivative securities

Accumulated Other Comprehensive Income (Loss)

Pre-Tax

0.2

0.1

(0.7)

(0.6)

Tax Benefit (Expense)

(0.1)

0.0

(0.1)

Other comprehensive income (loss)

0.1

(0.8)

(0.7)

Change in net unrealized gain (loss) on investment securities

Accumulated Other Comprehensive Income (Loss)

Pre-Tax

(6.8)

5.8

(6.6)

(34.6)

Tax Benefit (Expense)

2.5

(1.8)

3.2

13.8

Other comprehensive income (loss)

$ (4.3)

$ 4.0

$ (3.4)

^[1]

$ (20.8)

[1]	See Note 3 for amounts reclassified from Other comprehensive income (loss).

Comprehensive Income - Schedule of Components of Accumulated Other Comprehensive Income (Details) - USD ($)
$ in Millions

3 Months Ended

9 Months Ended

Sep. 30, 2017

Sep. 30, 2016

Sep. 30, 2017

Sep. 30, 2016

Components of Accumulated other comprehensive income, net of taxes

Beginning Balance

$ 4,426.5

$ 3,769.1

Other comprehensive gain (loss) before reclassifications

105.5

Amounts reclassified

(17.6)

Other comprehensive income (loss)

$ 48.8

$ (12.7)

87.9

(94.2)

Ending Balance

4,404.3

4,029.8

4,404.3

4,029.8

Foreign Currency Translation Adjustment

Components of Accumulated other comprehensive income, net of taxes

Beginning Balance

(213.9)

Other comprehensive gain (loss) before reclassifications

92.1

Amounts reclassified

0.0

Other comprehensive income (loss)

53.0

(16.8)

92.1

(72.7)

Ending Balance

(121.8)

Realized and Unrealized Gains (Losses) on Derivative Securities

Components of Accumulated other comprehensive income, net of taxes

Beginning Balance

0.4

Other comprehensive gain (loss) before reclassifications

(0.4)

Amounts reclassified

(0.4)

Other comprehensive income (loss)

0.1

(0.8)

(0.7)

Ending Balance

(0.4)

Change in net unrealized gain (loss) on investment securities

Components of Accumulated other comprehensive income, net of taxes

Beginning Balance

^[1]

9.8

Other comprehensive gain (loss) before reclassifications

^[1]

13.8

Amounts reclassified

^[1]

(17.2)

Other comprehensive income (loss)

(4.3)

$ 4.0

(3.4)

^[1]

$ (20.8)

Ending Balance

^[1]

6.4

AOCI Including Portion Attributable to Noncontrolling Interest [Member]

Components of Accumulated other comprehensive income, net of taxes

Beginning Balance

(203.7)

Ending Balance

$ (115.8)

[1]	See Note 3 for amounts reclassified from Other comprehensive income (loss).

Segment Information (Details) - segment	3 Months Ended	12 Months Ended
Segment Information (Details) - segment	Mar. 31, 2017	Dec. 31, 2016
Segment Reporting [Abstract]
Number of business segments		3
Number of operating segments	1
Number of reportable segments	1