Fair Value, Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Investments in securities [Abstract]
Total investments in securities	$ 32,975	$ 38,942
Securities sold, not yet purchased [Abstract]
Total securities sold, not yet purchased	129	0
Recurring Basis [Member]
Assets [Abstract]
Cash equivalents	13,538	12,467
Investments in securities [Abstract]
AFS - Common stocks	32,607	38,942
Trading - Common stocks	368	0
Total investments in securities	32,975	38,942
Total assets at fair value	46,513	51,409
Securities sold, not yet purchased [Abstract]
Trading - Common stocks	129	0
Total securities sold, not yet purchased	129	0
Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets [Abstract]
Cash equivalents	13,538	12,467
Investments in securities [Abstract]
AFS - Common stocks	32,607	38,942
Trading - Common stocks	368	0
Total investments in securities	32,975	38,942
Total assets at fair value	46,513	51,409
Securities sold, not yet purchased [Abstract]
Trading - Common stocks	129	0
Total securities sold, not yet purchased	129	0
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Cash equivalents	0	0
Investments in securities [Abstract]
AFS - Common stocks	0	0
Trading - Common stocks	0	0
Total investments in securities	0	0
Total assets at fair value	0	0
Securities sold, not yet purchased [Abstract]
Trading - Common stocks	0	0
Total securities sold, not yet purchased	0	0
Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets [Abstract]
Cash equivalents	0	0
Investments in securities [Abstract]
AFS - Common stocks	0	0
Trading - Common stocks	0	0
Total investments in securities	0	0
Total assets at fair value	0	0
Securities sold, not yet purchased [Abstract]
Trading - Common stocks	0	0
Total securities sold, not yet purchased	$ 0	$ 0