Investment Securities (Equity in Earnings of Investments) (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]
Equity in earnings (losses) from investments	$ 1,840	$ (468)	$ 54,199	$ (791)
Mutual fund and hedge funds
Schedule of Equity Method Investments [Line Items]
Equity in earnings (losses) from investments	1,468	(632)	775	(20)
Ladenburg Thalmann Financial Services Inc. (“LTS”)
Schedule of Equity Method Investments [Line Items]
Equity in earnings (losses) from investments	372	139	53,424	(846)
Other
Schedule of Equity Method Investments [Line Items]
Equity in earnings (losses) from investments	$ 0	$ 25	$ 0	$ 75