Redeemable Non-Controlling Interests in Consolidated Subsidiaries and Funds (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Noncontrolling Interest [Line Items]
Redeemable non-controlling interests in consolidated subsidiaries and funds	$ 171,245		$ 171,245		$ 86,076
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	4,344	$ 4,006	10,980	$ 13,409
Operating Entities
Noncontrolling Interest [Line Items]
Redeemable non-controlling interests in consolidated subsidiaries and funds	15,730		15,730		9,619
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	4,577	3,223	8,669	9,690
Consolidated Funds
Noncontrolling Interest [Line Items]
Redeemable non-controlling interests in consolidated subsidiaries and funds	155,515		155,515		$ 76,457
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	$ (233)	$ 783	$ 2,311	$ 3,719