Reserves in Addition to Account Balance, Based on Expected No-Lapse Guarantee Benefits and Expected Policy Assessments (Details) - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025	Sep. 30, 2025
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	$ 2,861	$ 2,992
Life policy reserves:
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	1,527	1,629
Investment contract reserves:
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	1,334	1,363
Term Life Insurance \| Life policy reserves:
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	1,035	1,103	$ 1,099
Whole Life Insurance \| Life policy reserves:
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	389	426	$ 430
Long-Duration Insurance, Other \| Life policy reserves:
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	103	100
Long-Duration Insurance, Other \| Investment contract reserves:
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	111	109
Deferred Fixed Annuity \| Investment contract reserves:
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	534	554
Universal life \| Investment contract reserves:
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	583	589
Structured Settlement Annuity \| Investment contract reserves:
Liability for Future Policy Benefit, by Product Segment
Life policy and investment contract reserves	$ 106	$ 111