Redeemable Noncontrolling Interests - Schedule of Redeemable Noncontrolling Interest (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Increase (Decrease) in Redeemable Non-controlling Interests [Roll Forward]
Beginning balance			$ 57,481
Net income (loss) attributable to noncontrolling interests	$ 749	$ 65	1,924	$ (80)
Net subscriptions (redemptions) and other			1,097
Ending balance	60,502		60,502
Consolidated Investment Products
Increase (Decrease) in Redeemable Non-controlling Interests [Roll Forward]
Beginning balance			2,384
Net income (loss) attributable to noncontrolling interests			339
Net subscriptions (redemptions) and other			4,123
Ending balance	6,846		6,846
Affiliate Noncontrolling Interests
Increase (Decrease) in Redeemable Non-controlling Interests [Roll Forward]
Beginning balance			55,097
Net income (loss) attributable to noncontrolling interests			1,585
Net subscriptions (redemptions) and other			(3,026)
Ending balance	$ 53,656		$ 53,656