Summary of Critical and Significant Accounting Policies - Marketable Securities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Equity securities:
Gross Unrealized (Loss) Gain	$ 33,104	$ 12,515	$ 5,710
Carrying Value	800	2,500
Available for sale
Total - Marketable securities, amortized cost	142,398	131,770
Total - Marketable securities, gross unrealized gain (loss)	49,431	15,998
Total - Marketable securities, carrying value	191,829	147,768
Proceeds from sale and maturities of marketable securities	16,600	113,500	147,500
Marketable securities, realized gain (loss)	3,400	2,100	1,300
Unrealized gain (loss) on equity securities recognized through income	33,104	12,515	$ 5,710
Investment funds - debt securities
Equity securities:
Amortized Cost	62,192	49,646
Gross Unrealized (Loss) Gain	(502)	985
Carrying Value	61,690	50,631
Available for sale
Unrealized gain (loss) on equity securities recognized through income	(502)	985
Common stock and stock funds
Equity securities:
Amortized Cost	79,155	81,074
Gross Unrealized (Loss) Gain	49,592	15,001
Carrying Value	128,747	96,075
Available for sale
Unrealized gain (loss) on equity securities recognized through income	49,592	15,001
Investment-grade unsecured debt
Available for sale
Amortized Cost	1,051	1,050
Gross Unrealized (Loss) Gain	341	12
Carrying Value	$ 1,392	$ 1,062