Investments - Summary of Other Equity Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Equity Method Investment	$ 57,275	$ 58,507
ABS [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment	40,052	38,699
Atalanta Sosnoff [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment	12,300	13,291
Luminis [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment	$ 4,923	$ 6,517