Non-controlling Interests (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Noncontrolling Interest [Line Items]
Non-redeemable non-controlling interests	$ 7,978	$ (49)	$ 9,610	$ (6,953)
Total non-controlling interest in net income (loss)	17,169	4,843	33,487	(905)
Non-redeemable non-controlling interest	36,857		36,857		$ 36,172
Redeemable non-controlling interest	344,104		344,104		392,959
CPH acquisition
Noncontrolling Interest [Line Items]
Redeemable non-controlling interest	8,664		8,664		8,665
Other
Noncontrolling Interest [Line Items]
Non-redeemable non-controlling interests	48	101	195	200
Non-redeemable non-controlling interest	689		689		1,550
Company-sponsored investment funds
Noncontrolling Interest [Line Items]
Non-redeemable non-controlling interests	7,930	(150)	9,415	(7,153)
Redeemable non-controlling interests	9,191	$ 4,892	23,877	$ 6,048
Non-redeemable non-controlling interest	36,168		36,168		34,622
Redeemable non-controlling interest	$ 335,440		$ 335,440		$ 384,294