Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Net Investment Income [Line Items]
Gross investment income	$ 363,764	$ 322,083
Investment expense	(3,472)	(2,244)
Net investment income	360,292	319,839
Fixed maturity securities, including cash and cash equivalents and loans receivable
Net Investment Income [Line Items]
Gross investment income	313,788	335,248
Investment funds
Net Investment Income [Line Items]
Gross investment income	27,023	(29,349)
Arbitrage Trading Account
Net Investment Income [Line Items]
Gross investment income	16,329	18,011
Equity securities
Net Investment Income [Line Items]
Gross investment income	10,641	11,336
Real estate
Net Investment Income [Line Items]
Gross investment income	$ (4,017)	$ (13,163)