Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Net Investment Income [Line Items]
Gross investment income	$ 246,812	$ 173,623	$ 472,925	$ 349,108
Investment expense	(1,660)	(2,049)	(4,374)	(4,022)
Net investment income	245,152	171,574	468,551	345,086
Fixed maturity securities, including cash and cash equivalents and loans receivable
Net Investment Income [Line Items]
Gross investment income	217,830	124,389	413,473	225,673
Arbitrage trading account (1)
Net Investment Income [Line Items]
Gross investment income	(1,186)	33,861	993	85,874
Equity securities
Net Investment Income [Line Items]
Gross investment income	15,254	12,797	29,000	23,653
Investment funds
Net Investment Income [Line Items]
Gross investment income	17,037	4,127	35,293	13,313
Real estate
Net Investment Income [Line Items]
Gross investment income	$ (2,123)	$ (1,551)	$ (5,834)	$ 595