Investments - Disposition of Fixed Income and Equity Securities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Summary of the disposition of fixed income and equity securities
Fixed income securities - available-for-sale	$ 50,135	$ 53,300	$ 63,811
Fixed income securities - available-for-sale	504,168	1,393,674	376,750
Net Realized Gain (Loss) - Fixed income securities - available-for-sale	(2,000)
Net Realized Gain (Loss) - Equity securities	22,232	20,287	62,512
SALES
Summary of the disposition of fixed income and equity securities
Fixed income securities - available-for-sale	49,960	51,355	65,262
Gross Realized Gains - Fixed income securities - available-for-sale	451	287	2,161
Gross Realized Losses - Fixed income securities - available-for-sale	(2,174)	(2,849)	(815)
Net Realized Gain (Loss) - Fixed income securities - available-for-sale	(1,723)	(2,562)	1,346
Proceeds from Sales - Equity securities	51,881	62,212	180,256
Gross Realized Gains - Equity securities	23,482	21,623	64,298
Gross Realized Losses - Equity securities	(1,250)	(1,336)	(1,786)
Net Realized Gain (Loss) - Equity securities	22,232	20,287	62,512
Calls And Maturities Of Marketable Securities
Summary of the disposition of fixed income and equity securities
Fixed income securities - available-for-sale	506,910	1,393,704	376,751
Gross Realized Gains - Fixed income securities - available-for-sale	39	196	638
Gross Realized Losses - Fixed income securities - available-for-sale	(162)	(55)	(125)
Net Realized Gain (Loss) - Fixed income securities - available-for-sale	$ (123)	$ 141	$ 513