Consolidated Company-Sponsored Investment Funds - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) investments	Dec. 31, 2019 USD ($)	Jun. 30, 2020 USD ($)
Derivative [Line Items]
Cash collateral payable to trade counterparties	$ 400	$ 300
Cash collateral received	6,400	4,300
Maximum risk of loss in investment in VIEs	7,100
Institutional investment advisory and services fees receivable	$ 148,746	148,744
Seed capital
Derivative [Line Items]
Investment owned at fair value, number of deconsolidated funds | investments	5
Investment owned at fair value, deconsolidated amount			$ 94,600
VIEs
Derivative [Line Items]
Futures, forwards and swaps held	$ (3,700)	300
Gains (losses) on derivatives	(600)	3,300
Cash collateral payable to trade counterparties	513	1,631
Cash collateral received	4,200	3,200
VOEs
Derivative [Line Items]
Futures, forwards and swaps held	(200)	700
Gains (losses) on derivatives	200	500
Cash collateral payable to trade counterparties	0	534
Cash collateral received	100	$ 1,200
Variable Interest Entity, Not Primary Beneficiary
Derivative [Line Items]
Net assets	73,400,000
Institutional investment advisory and services fees receivable	$ 77,600