Investments - Marketable Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Investment Securities - fair value
Cost	$ 50,434	$ 31,999
Fair Value	54,448	39,990
Sponsored funds
Investment Securities - fair value
Cost	40,304	22,378
Fair Value	40,791	25,909
Equity securities
Investment Securities - fair value
Cost	10,123	9,614
Fair Value	13,642	14,078
Debt securities
Investment Securities - fair value
Cost	7	7
Fair Value	$ 15	$ 3