Redeemable Non-Controlling Interests in Consolidated Subsidiaries and Funds (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Noncontrolling Interest [Line Items]
Redeemable non-controlling interests in consolidated subsidiaries and funds	$ 186,911				$ 86,076				$ 186,911	$ 86,076
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	4,266	$ 4,344	$ 3,916	$ 2,720	2,155	$ 4,006	$ 5,216	$ 4,187	15,246	15,564	$ 13,193
Operating Entities
Noncontrolling Interest [Line Items]
Redeemable non-controlling interests in consolidated subsidiaries and funds	10,906				9,619				10,906	9,619
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds									9,503	10,094	10,461
Consolidated Funds
Noncontrolling Interest [Line Items]
Redeemable non-controlling interests in consolidated subsidiaries and funds	$ 176,005				$ 76,457				176,005	76,457
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds									$ 5,743	$ 5,470	$ 2,732