Summary of Aggregate Fair Value of Assets (Detail) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022	Jan. 01, 2021
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Separate Account Assets	$ 4,244	$ 4,417	$ 6,081
Equity funds
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Separate Account Assets	1,866	1,866
Balanced funds
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Separate Account Assets	1,831	1,962
Bond funds
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Separate Account Assets	306	332
Money market funds
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Separate Account Assets	$ 241	$ 257