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Investments of Operating Entities and Consolidated Funds - Operating Entities - Equity Method Investment - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Schedule of Equity Method Investments [Line Items]
Other than Temporary Impairment Losses, Investments				$ 0
Surf House Ocean Views Holdings, LLC
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	40.00%		40.00%
Other than Temporary Impairment Losses, Investments			$ 11,300
Net Gains (Losses) on Securities, Derivatives and Other Investments
Schedule of Equity Method Investments [Line Items]
Income (Loss) from Equity Method Investments	$ 4,000	$ 2,700	$ 10,500	$ 23,100
Minimum
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	15.00%		15.00%
Maximum
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	55.00%		55.00%