Investments - Schedule of Fixed Maturities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Amortized Cost, net
Due in one year or less	$ 131,203
Due after one year through five years	1,015,277
Due after five years through ten years	1,691,289
Due after ten years through twenty years	7,125,279
Due after twenty years	7,906,891
Mortgage-backed and asset-backed securities	126,447
Fixed maturities, net of allowance for credit losses	17,996,386
Fair Value
Due in one year or less	132,177
Due after one year through five years	1,045,058
Due after five years through ten years	1,759,932
Due after ten years through twenty years	7,207,999
Due after twenty years	6,896,832
Mortgage-backed and asset-backed securities	139,969
Fixed maturities, fair value	$ 17,181,967	$ 21,305,287