Investments - Schedule of Marketable Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Investment Securities - fair value
Cost	$ 37,797	$ 31,999
Fair Value	40,904	39,990
Sponsored funds
Investment Securities - fair value
Cost	27,323	22,378
Fair Value	26,598	25,909
Equity securities
Investment Securities - fair value
Cost	10,467	9,614
Fair Value	14,303	14,078
Debt securities
Investment Securities - fair value
Cost	7	7
Fair Value	$ 3	$ 3