Non-controlling Interests (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Variable Interest Entity [Line Items]
Non-redeemable non-controlling interests	$ 69	$ 9,632	$ 11,398
Net income of consolidated entities attributable to non-controlling interests	21,910	58,397	21,488
Non-redeemable non-controlling interest	949	1,564
Redeemable non-controlling interest	148,809	601,587
CPH Acquisition
Variable Interest Entity [Line Items]
Non-redeemable non-controlling interest	949	807
Redeemable non-controlling interest	2,888	5,364
Other
Variable Interest Entity [Line Items]
Non-redeemable non-controlling interests	188	279	312
Company-Sponsored Investment Funds
Variable Interest Entity [Line Items]
Non-redeemable non-controlling interests	(119)	9,353	11,086
Redeemable non-controlling interests	21,841	48,765	$ 10,090
Non-redeemable non-controlling interest	0	757
Redeemable non-controlling interest	$ 145,921	$ 596,223