Investments - Schedule of Fixed Maturities by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Amortized Cost, net
Due in one year or less	$ 110,352
Due after one year through five years	850,072
Due after five years through ten years	1,988,461
Due after ten years through twenty years	8,376,525
Due after twenty years	7,468,886
Mortgage-backed and asset-backed securities	123,503
Fixed maturities, net of allowance for credit losses	18,917,799
Fair Value
Due in one year or less	109,817
Due after one year through five years	858,859
Due after five years through ten years	2,011,887
Due after ten years through twenty years	8,164,465
Due after twenty years	6,600,692
Mortgage-backed and asset-backed securities	124,486
Fixed maturities, fair value	$ 17,870,206	$ 16,503,365