Investments - Investments, Fair Value (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity Investments, at Fair Value, Cost	$ 22,490	$ 34,727
Equity Investments, at Fair Value, Unrealized Gain/(Loss)	(1,627)	1,027
Equity Investments, at Fair Value	20,863	35,754
Trading Securities, Amortized Cost		9,099
Trading Securities Unrealized Gain Loss		1
Total Trading Securities	0	9,100
Securities Short Sold Proceeds	660
Securities Short Sold Unrealized (Gain)/Loss	30
Securities Short Sold,Fair Value	690
Equity Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity Investments, at Fair Value, Cost	15,211	14,712
Equity Investments, at Fair Value, Unrealized Gain/(Loss)	(1,655)	1,003
Equity Investments, at Fair Value	13,556	15,715
Securities Short Sold Proceeds	660
Securities Short Sold Unrealized (Gain)/Loss	30
Securities Short Sold,Fair Value	690
Mutual Funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity Investments, at Fair Value, Cost	7,279	20,015
Equity Investments, at Fair Value, Unrealized Gain/(Loss)	28	24
Equity Investments, at Fair Value	7,307	20,039
U.S. Treasury Bills
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading Securities, Amortized Cost		9,099
Trading Securities Unrealized Gain Loss		1
Total Trading Securities	$ 0	$ 9,100