Investments - Schedule of Contractual Maturities of Fixed Maturity Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Amortized  Cost
Due in less than one year	$ 364,501
Due after one through five years	8,117,971
Due after five through ten years	4,072,142
Due after ten years	356,268
Amortized cost	15,038,551	$ 13,552,579
Debt Securities, Trading, and Equity Securities, FV-NI [Abstract]
Due in less than one year	356,770
Due after one through five years	7,875,771
Due after five through ten years	3,805,287
Due after ten years	311,856
Fixed maturity investments	14,351,402	13,507,131
Mortgage-backed
Amortized  Cost
Amortized cost	1,009,205
Debt Securities, Trading, and Equity Securities, FV-NI [Abstract]
Fixed maturity investments	924,416
Asset-backed
Amortized  Cost
Amortized cost	1,118,464
Debt Securities, Trading, and Equity Securities, FV-NI [Abstract]
Fixed maturity investments	$ 1,077,302	$ 1,068,543