Investments - Schedule of Fair Value of Fixed Maturity Investments Trading (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Schedule of Investments [Line Items]
Fixed maturity investments	$ 14,351,402	$ 13,507,131
U.S. treasuries
Schedule of Investments [Line Items]
Fixed maturity investments	7,180,129	6,247,779
Corporate
Schedule of Investments [Line Items]
Fixed maturity investments	4,390,568	3,689,286
Agencies
Schedule of Investments [Line Items]
Fixed maturity investments	395,149	361,684
Non-U.S. government
Schedule of Investments [Line Items]
Fixed maturity investments	383,838	549,613
Residential mortgage-backed
Schedule of Investments [Line Items]
Fixed maturity investments	710,429	955,301
Commercial mortgage-backed
Schedule of Investments [Line Items]
Fixed maturity investments	213,987	634,925
Asset-backed
Schedule of Investments [Line Items]
Fixed maturity investments	$ 1,077,302	$ 1,068,543