Investments - Schedule of Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Cost	$ 31,999	$ 55,882
Fair Value	39,990	60,990
Sponsored funds
Debt Securities, Available-for-sale [Line Items]
Cost	22,378	44,588
Fair Value	25,909	47,654
Equity securities
Debt Securities, Available-for-sale [Line Items]
Cost	9,614	11,250
Fair Value	14,078	13,320
Debt securities
Debt Securities, Available-for-sale [Line Items]
Cost	7	44
Fair Value	$ 3	$ 16