Schedule II - Financial Information of Registrant - Parent Company Statement of Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenues
Net investment income	$ 258,430	$ 195,658	$ 147,909
Net gains (losses) on investments and other financial instruments (includes net realized gains (losses) on investments of $(10,733), $(8,306) and $20,842) (Note 6)	10,241	(80,733)	15,603
Other income	6,247	2,454	3,412
Total revenues	1,240,588	1,190,726	1,329,932
Expenses
Other operating expenses	347,578	381,148	323,686
Total expenses (Note B)	473,101	237,947	565,100
Pretax income	767,487	952,779	764,832
Income tax provision	164,368	209,845	164,161
Net income	603,119	742,934	600,671
Other comprehensive income (loss), net of tax	125,948	(576,892)	(143,632)
Comprehensive income	729,067	166,042	457,039
Parent Company
Revenues
Net investment income	55,370	20,584	7,540
Net gains (losses) on investments and other financial instruments (includes net realized gains (losses) on investments of $(10,733), $(8,306) and $20,842) (Note 6)	(5,844)	(4,322)	980
Other income	0	78	11
Total revenues	49,526	16,340	8,531
Expenses
Other operating expenses	5,025	2,043	3,163
Total expenses (Note B)	5,025	2,043	3,163
Pretax income	44,501	14,297	5,368
Income tax provision	12,479	8,148	1,167
Equity in net income of affiliates	571,097	736,785	596,470
Net income	603,119	742,934	600,671
Other comprehensive income (loss), net of tax	125,949	(576,892)	(143,632)
Comprehensive income	$ 729,068	$ 166,042	$ 457,039