Non-controlling Interests (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Noncontrolling Interest [Line Items]
Non-redeemable non-controlling interests	$ 16	$ 56
Total non-controlling interest in net income	10,116	22,650
Non-redeemable non-controlling interest	945		$ 949
Redeemable non-controlling interest	158,873		148,809
CPH acquisition
Noncontrolling Interest [Line Items]
Non-redeemable non-controlling interest	945		949
Redeemable non-controlling interest	2,888		2,888
Other
Noncontrolling Interest [Line Items]
Non-redeemable non-controlling interests	16	98
Company-sponsored investment funds
Noncontrolling Interest [Line Items]
Non-redeemable non-controlling interests	0	(42)
Redeemable non-controlling interests	10,100	$ 22,594
Non-redeemable non-controlling interest	0		0
Redeemable non-controlling interest	$ 155,985		$ 145,921