Redeemable Non-Controlling Interests in Consolidated Subsidiaries and Funds (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Noncontrolling Interest [Line Items]
Redeemable non-controlling interests in consolidated subsidiaries and funds	$ 421,661		$ 421,661		$ 379,205
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	5,162	$ 18,478	35,412	$ (2,524)
Operating Entities
Noncontrolling Interest [Line Items]
Redeemable non-controlling interests in consolidated subsidiaries and funds	5,766		5,766		7,638
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	(266)	1,433	1,457	2,880
Consolidated Funds
Noncontrolling Interest [Line Items]
Redeemable non-controlling interests in consolidated subsidiaries and funds	415,895		415,895		$ 371,567
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	$ 5,428	$ 17,045	$ 33,955	$ (5,404)