Long-Term Investments (Equity-Method Investments) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Equity-method investments	$ 16,589		$ 15,841
Proceeds from long-term equity method investment	414	$ 240
Equity in losses from investments	(1,162)	$ 1,061
Indian Creek Investors LP (“Indian Creek”)
Schedule of Equity Method Investments [Line Items]
Equity-method investments	$ 5,484		4,498
Equity-method ownership percentage	22.87%
Boyar Value Fund (“Boyar”)
Schedule of Equity Method Investments [Line Items]
Equity-method investments	$ 8,927		9,026
Equity-method ownership percentage	33.16%
Quoted market value	$ 8,927
Ladenburg Thalmann Financial Services Inc. (“LTS”)
Schedule of Equity Method Investments [Line Items]
Equity-method investments	$ 2,178		2,317
Equity-method ownership percentage	7.69%
Quoted market value	$ 49,675
Castle Brands, Inc. (“Castle”)
Schedule of Equity Method Investments [Line Items]
Equity-method investments	$ 0		$ 0
Equity-method ownership percentage	7.82%
Quoted market value	$ 15,990