Redeemable Non-Controlling Interests in Consolidated Subsidiaries and Funds (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Noncontrolling Interest [Line Items]
Redeemable non-controlling interests in consolidated subsidiaries and funds	$ 392,326		$ 440,604
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	11,156	$ 9,105
Operating Entities
Noncontrolling Interest [Line Items]
Redeemable non-controlling interests in consolidated subsidiaries and funds	7,420		6,113
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	1,620	717
Consolidated Funds
Noncontrolling Interest [Line Items]
Redeemable non-controlling interests in consolidated subsidiaries and funds	384,906		$ 434,491
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	$ 9,536	$ 8,388