Investments of Operating Entities and Consolidated Funds - Operating Entities - Equity Method Investment (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Schedule of Equity Method Investments [Line Items]
Net gains (losses) on other investments	$ 12,645	$ (62)

Amount of income (loss) for proportionate share of equity method investee's income (loss).

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