Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Net Investment Income [Line Items]
Gross investment income	$ 326,374	$ 272,781	$ 1,023,430	$ 745,705
Investment expense	(2,618)	(1,837)	(7,707)	(6,211)
Net investment income	323,756	270,944	1,015,723	739,494
Fixed maturity securities, including cash and cash equivalents and loans receivable
Net Investment Income [Line Items]
Gross investment income	295,272	239,727	954,655	653,200
Arbitrage trading account (1)
Net Investment Income [Line Items]
Gross investment income	4,741	4,450	868	5,444
Equity securities
Net Investment Income [Line Items]
Gross investment income	12,203	12,714	35,924	41,714
Investment funds
Net Investment Income [Line Items]
Gross investment income	17,869	17,876	52,562	53,168
Real estate
Net Investment Income [Line Items]
Gross investment income	$ (3,711)	$ (1,986)	$ (20,579)	$ (7,821)