Changes in the redemption value of Affiliate Equity and other transactions with Affiliate partners.

No definition available.

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- Definition

Amount of other increase (decrease) in additional paid in capital (APIC).

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No definition available.

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- Definition

This element represents the amount of recognized equity-based compensation during the period, that is, the amount recognized as expense in the income statement (or as asset if compensation is capitalized). Alternate captions include the words "stock-based compensation".

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- Definition

Amount of increase in additional paid in capital (APIC) resulting from a tax benefit associated with share-based compensation plan other than an employee stock ownership plan (ESOP). Includes, but is not limited to, excess tax benefit.

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- Definition

Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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- Definition

Decrease in noncontrolling interest balance from payment of dividends or other distributions by the non-wholly owned subsidiary or partially owned entity, included in the consolidation of the parent entity, to the noncontrolling interest holders.

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- Definition

Amount of increase in noncontrolling interest from subsidiary issuance of equity interests to noncontrolling interest holders.

+ References

No definition available.

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- Definition

Amount after tax and reclassification adjustments of other comprehensive income (loss).

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- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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- Definition

Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.

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- Definition

Number of shares issued during the period as a result of the conversion of convertible securities.

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- Definition

The gross value of stock issued during the period upon the conversion of convertible securities.

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Value of stock (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of stock value of such awards forfeited. Stock issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

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Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

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CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (USD $) In Millions, unless otherwise specified	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Treasury Stock at Cost	Noncontrolling Interest
Beginning Balance at Dec. 31, 2013	$ 3,144.6	$ 0.5	$ 479.9	$ 74.0	$ 1,711.2	$ (131.4)	$ 1,010.4
Beginning Balance (in shares) at Dec. 31, 2013	53.9us-gaap_CommonStockSharesOutstanding
Increase (Decrease) in Stockholders' Equity
Net income	159.4us-gaap_ProfitLoss				77.2		82.2
Share-based compensation	6.5		6.5
Common stock issued under share-based incentive plans	(37.7)		(67.5)			29.8
Tax benefit from share-based incentive plans	33.1		33.1
Settlement of senior convertible securities (in shares)	1.9
Settlement of senior convertible securities	276.5	0.1	276.4
Forward equity	(9.4)		(9.4)
Investments in Affiliates	78.9						78.9
Affiliate equity activity	(34.8)amg_ChangesInAffiliateEquity		(27.4)				(7.4)
Distributions to non-controlling interests	(219.0)						(219.0)
Other comprehensive income (loss)	(22.4)			(22.6)			0.2
Ending Balance at Mar. 31, 2014	3,375.7	0.6	691.6	51.4	1,788.4	(101.6)	945.3
Ending Balance (in shares) at Mar. 31, 2014	55.8us-gaap_CommonStockSharesOutstanding
Beginning Balance at Dec. 31, 2014	3,643.2	0.6	672.2	31.8	2,163.3	(240.9)	1,016.2
Beginning Balance (in shares) at Dec. 31, 2014	55.8us-gaap_CommonStockSharesOutstanding
Increase (Decrease) in Stockholders' Equity
Net income	220.7us-gaap_ProfitLoss				128.0		92.7
Share-based compensation	8.0		8.0
Common stock issued under share-based incentive plans	40.1		(100.3)			140.4
Tax benefit from share-based incentive plans	34.5		34.5
Affiliate equity activity	(88.4)amg_ChangesInAffiliateEquity		(95.2)				6.8
Share repurchases	(150.0)					(150.0)
Distributions to non-controlling interests	(114.6)						(114.6)
Other comprehensive income (loss)	(48.7)			(34.6)			(14.1)
Ending Balance at Mar. 31, 2015	$ 3,544.8	$ 0.6	$ 519.2	$ (2.8)	$ 2,291.3	$ (250.5)	$ 987.0
Ending Balance (in shares) at Mar. 31, 2015	55.8us-gaap_CommonStockSharesOutstanding