Fair Value Measurements - Fair Values of Separate Account Assets (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Guaranteed separate accounts	$ 562	$ 585
Non-guaranteed separate accounts	6,020	5,936
Subtotal	6,582	6,521
Non-guaranteed separate accounts priced at NAV as a practical expedient	758	757
Separate account assets	7,340	7,278	[1]
Pension Plans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-guaranteed separate accounts	4,000	4,000
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	213	203
Non-guaranteed separate accounts	221	211
Subtotal	434	414
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Guaranteed separate accounts	349	382
Non-guaranteed separate accounts	5,586	5,522
Subtotal	5,935	5,904
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	213	203
Subtotal	213	203
Significant Unobservable Inputs (Level 3) | Pension Plans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-guaranteed separate accounts	$ 200	$ 200

[1] Amounts have been restated to reflect the adoption of Targeted Improvements to the Accounting for Long-Duration Contracts in 2023. See Note 2 to the Consolidated Financial Statements for further information.