Investment Securities (Equity in Earnings of Investments) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Schedule of Equity Method Investments [Line Items]
Equity in earnings (losses) from investments	$ 2,207	$ (1,685)	$ 52,359	$ (323)
Mutual fund and hedge funds
Schedule of Equity Method Investments [Line Items]
Equity in earnings (losses) from investments	2,207	(230)	(693)	612
Ladenburg Thalmann Financial Services Inc. (“LTS”)
Schedule of Equity Method Investments [Line Items]
Equity in earnings (losses) from investments	0	(1,480)	53,052	(985)
Other
Schedule of Equity Method Investments [Line Items]
Equity in earnings (losses) from investments	$ 0	$ 25	$ 0	$ 50

Amount of income (loss) for proportionate share of equity method investee's income (loss).

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