Reserves in Addition to Account Balance, Based on Expected No-Lapse Guarantee Benefits and Expected Policy Assessments (Detail) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	$ 3,027	$ 3,014
Life policy reserves:
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	1,447	1,428
Life policy reserves: | Ordinary/traditional life
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	1,395	1,376
Life policy reserves: | Other
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	52	52
Investment contract reserves:
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	1,580	1,586
Investment contract reserves: | Deferred annuities
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	757	762
Investment contract reserves: | Universal life
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	680	679
Investment contract reserves: | Structured Settlement Annuity
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	135	136
Investment contract reserves: | Other
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	$ 8	$ 9