Investments Of Operating Entities And Consolidated Funds - Consolidated Funds - Other Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Investment Holdings [Line Items]
Portfolio Funds, Consolidated Funds	$ 100,252	$ 192,670
Enterprise LP [Member]
Investment Holdings [Line Items]
Portfolio Funds, Consolidated Funds	100,252	104,475
Cowen Sustainable Investments I LP
Investment Holdings [Line Items]
Portfolio Funds, Consolidated Funds	$ 0	$ 88,195