Redeemable Noncontrolling Interests - Schedule of Redeemable Noncontrolling Interest (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Increase (Decrease) in Redeemable Non-controlling Interests [Roll Forward]
Beginning balance	$ 57,481
Net income (loss) attributable to noncontrolling interests	1,175	$ (145)
Net subscriptions (redemptions) and other	347
Ending balance	59,003
Consolidated investment products
Increase (Decrease) in Redeemable Non-controlling Interests [Roll Forward]
Beginning balance	2,384
Net income (loss) attributable to noncontrolling interests	338
Net subscriptions (redemptions) and other	1,923
Ending balance	4,645
Affiliate Noncontrolling Interests
Increase (Decrease) in Redeemable Non-controlling Interests [Roll Forward]
Beginning balance	55,097
Net income (loss) attributable to noncontrolling interests	837
Net subscriptions (redemptions) and other	(1,576)
Ending balance	$ 54,358