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Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Net Investment Income [Line Items]
Gross investment income	$ 354,173	$ 326,374	$ 1,099,788	$ 1,023,430
Investment expense	(2,935)	(2,618)	(8,955)	(7,707)
Net investment income	351,238	323,756	1,090,833	1,015,723
Fixed maturity securities, including cash and cash equivalents and loans receivable
Net Investment Income [Line Items]
Gross investment income	324,319	295,272	960,625	954,655
Arbitrage Trading Account
Net Investment Income [Line Items]
Gross investment income	16,309	17,869	56,309	52,562
Equity securities
Net Investment Income [Line Items]
Gross investment income	11,497	12,203	34,623	35,924
Investment funds
Net Investment Income [Line Items]
Gross investment income	5,421	4,741	59,713	868
Real estate
Net Investment Income [Line Items]
Gross investment income	$ (3,373)	$ (3,711)	$ (11,482)	$ (20,579)

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