Investments - Schedule of Fixed Maturities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Amortized Cost, net
Due in one year or less	$ 162,473
Due after one year through five years	1,020,894
Due after five years through ten years	1,716,490
Due after ten years through twenty years	7,477,686
Due after twenty years	7,670,293
Mortgage-backed and asset-backed securities	125,635
Fixed maturities, net of allowance for credit losses	18,173,471
Fair Value
Due in one year or less	163,087
Due after one year through five years	1,021,499
Due after five years through ten years	1,695,969
Due after ten years through twenty years	6,932,181
Due after twenty years	6,058,402
Mortgage-backed and asset-backed securities	134,002
Fixed maturities, fair value	$ 16,005,140	$ 21,305,287