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		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Summarized Financial Information, Assets	$ 59,379		$ 59,379		$ 95,825
Liabilities	0		0		82,482
Equity	59,379		59,379		$ 13,343
Revenue	274	$ 4,564	54,717	$ 83,287
Expenses	0	0	0	0
Net realized and unrealized gain (loss)	77	55	412	717
Net Income	$ 351	$ 4,619	$ 55,129	$ 84,004