Investments - Disposition of Fixed Income and Equity Securities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Summary of the disposition of fixed income and equity securities
Fixed income securities - available-for-sale	$ 53,300	$ 63,811	$ 84,587
Fixed income securities - available-for-sale	1,393,674	376,750	283,107
Net Realized Gain (Loss) - Equity securities	20,287	62,512	15,796
SALES
Summary of the disposition of fixed income and equity securities
Fixed income securities - available-for-sale	51,355	65,262	84,697
Gross Realized Gains - Fixed income securities - available-for-sale	287	2,161	5,454
Gross Realized Losses - Fixed income securities - available-for-sale	(2,849)	(815)	(1,777)
Net Realized Gain (Loss) - Fixed income securities - available-for-sale	(2,562)	1,346	3,677
Proceeds from Sales - Equity securities	62,212	180,256	79,368
Gross Realized Gains - Equity securities	21,623	64,298	25,338
Gross Realized Losses - Equity securities	(1,336)	(1,786)	(9,542)
Net Realized Gain (Loss) - Equity securities	20,287	62,512	15,796
Calls And Maturities Of Marketable Securities
Summary of the disposition of fixed income and equity securities
Fixed income securities - available-for-sale	1,393,704	376,751	283,107
Gross Realized Gains - Fixed income securities - available-for-sale	196	638	821
Gross Realized Losses - Fixed income securities - available-for-sale	(55)	(125)	(27)
Net Realized Gain (Loss) - Fixed income securities - available-for-sale	$ 141	$ 513	$ 794