Segment Reporting - Reconciliation of Income Before Provision for Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting Information [Line Items]
Income before provision for income taxes	$ 474.1	$ 541.2	$ 1,089.4	$ 1,013.6
Adjustments:
Other non-operating (income) expense	(2.9)	(4.6)	(1.8)	25.6
Net income attributable to non-controlling interests in consolidated entities	(370.8)	(369.7)	(809.9)	(694.2)
Reconciling Items
Adjustments:
Equity-based compensation issued in conjunction with the initial public offering, acquisitions and strategic investments	88.6	91.0	147.6	153.4
Acquisition related charges and amortization of intangibles	(2.3)	62.0	38.3	142.1
Other non-operating (income) expense	(2.9)	(4.6)	(1.8)	25.6
Tax expense associated with performance fee compensation	(9.1)	(28.3)	(14.3)	(38.5)
Net income attributable to non-controlling interests in consolidated entities	(370.8)	(369.7)	(809.9)	(694.2)
Other adjustments	2.0	(2.2)	3.0	(0.9)
Net performance fees	26.0	(18.8)	51.5	(12.6)
Operating Segments
Adjustments:
Economic Net Income	179.6	289.4	452.3	601.1
Net performance fees	149.2	233.4	431.0	529.8
Investment Income (Loss)	11.0	(4.7)	(17.0)	(12.6)
Equity-based compensation	27.9	19.5	60.2	33.5
Fee Related Earnings	47.3	80.2	98.5	117.4
Realized performance fees, net of related compensation	332.7	231.3	511.1	371.4
Realized investment income (loss)	6.1	11.5	(75.9)	16.8
Distributable Earnings	$ 386.1	$ 323.0	$ 533.7	$ 505.6