Investments, Investment Income By Category (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	$ 160,598	$ 159,608	$ 171,347
Investment expenses	(4,160)	(5,212)	(4,302)
Net investment income	156,438	154,396	167,045
Fixed income securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	160,030	157,065	165,523
Equity securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	471	620	406
Cash equivalents
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	75	1,648	4,444
Other
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	$ 22	$ 275	$ 974