Redeemable Noncontrolling Interest in Subsidiaries (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019
Increase (Decrease) in Temporary Equity [Roll Forward]
Temporary equity, beginning balance	$ 199,261	$ 212,086	$ 186,200	$ 182,513
Net Income (Loss)	3,605	(913)	1,116	65
Other Comprehensive Income (Loss), net of tax	(435)	(11,454)	(4,600)	3,714
Subscriptions—Redeemable Noncontrolling Interest Holders	6,225	5,577	1,822	42
Consolidation/(Deconsolidation)		(4,019)
Stock Award Activity	2,087	2,153	1,773	2,126
Distributions to Noncontrolling Interest in Subsidiaries	(4,058)	(6,039)	(541)	(2,260)
Business Acquisition			(386)
Change in Estimated Redemption Value of Redeemable Noncontrolling Interests	(2,013)	1,870	16,604
Temporary equity, ending balance	204,672	199,261	201,988	186,200
Consolidated Investment Companies
Increase (Decrease) in Temporary Equity [Roll Forward]
Temporary equity, beginning balance	12,589	19,872	10,086	11,626
Net Income (Loss)	2,560	(2,802)	340	678
Subscriptions—Redeemable Noncontrolling Interest Holders	6,225	5,577	1,822	42
Consolidation/(Deconsolidation)		(4,019)
Distributions to Noncontrolling Interest in Subsidiaries	(4,058)	(6,039)	(541)	(2,260)
Temporary equity, ending balance	17,316	12,589	11,707	10,086
Hermes
Increase (Decrease) in Temporary Equity [Roll Forward]
Temporary equity, beginning balance	186,672	192,214	176,114	170,887
Net Income (Loss)	1,045	1,889	776	(613)
Other Comprehensive Income (Loss), net of tax	(435)	(11,454)	(4,600)	3,714
Stock Award Activity	2,087	2,153	1,773	2,126
Business Acquisition			(386)
Change in Estimated Redemption Value of Redeemable Noncontrolling Interests	(2,013)	1,870	16,604
Temporary equity, ending balance	$ 187,356	$ 186,672	$ 190,281	$ 176,114