Investments - Gross Realized Gains and Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Debt securities:
Gross realized gains	$ 63	$ 4,646	$ 269
Gross realized losses	(6)	(8)	(54)
Total debt securities	57	4,638	215
Equity securities:
Gross realized gains	4,605	4,854	1,020
Gross realized losses	(1,784)	(1,366)	(39)
Total equity securities	2,821	3,488	981
Total net realized investment gains	$ 2,878	$ 8,126	$ 1,196