Investments of Operating Entities and Consolidated Funds - Operating Entities - Regulation S-X (Details) - Equity Method Investee, Exceeded Threshold for Income Test [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Summarized Financial Information, Assets	$ 793,662		$ 818,193
Liabilities	26,054		77,092
Equity	767,608		$ 741,101
Revenue	58,920	$ 28,001
Expenses	(11,661)	(27,522)
Net realized and unrealized gain (loss)	(49,113)	91,334
Net Income	(2,579)	91,108
Equity Method Investment, Summarized Financial Information, Income (Loss) from Continuing Operations	(1,854)	91,813
Equity method investment, summarized financial information, income tax expense (benefit)	$ (725)	$ (705)