Fair Value Measurements - Fair Values of Separate Account Assets (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Guaranteed separate accounts	$ 436	$ 503
Non-guaranteed separate accounts	6,787	7,870
Subtotal	7,223	8,373
Non-guaranteed separate accounts priced at NAV as a practical expedient	920	842
Total	8,143	9,215
Separate account assets of business classified as held for sale	(648)	(878)
Separate account assets	7,495	8,337
Pension Plan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-guaranteed separate accounts	4,200	4,500
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Guaranteed separate accounts	208	227
Non-guaranteed separate accounts	212	1,130
Subtotal	420	1,357
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Guaranteed separate accounts	228	276
Non-guaranteed separate accounts	6,326	6,406
Subtotal	6,554	6,682
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Guaranteed separate accounts	0	0
Non-guaranteed separate accounts	249	334
Subtotal	249	334
Significant Unobservable Inputs (Level 3) | Pension Plan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-guaranteed separate accounts	$ 200	$ 300