Fair Value Measurements - Fair Values of Separate Account Assets (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Guaranteed separate accounts	$ 503
Guaranteed separate accounts		$ 523
Non-guaranteed separate accounts	7,870
Non-guaranteed separate accounts		7,880
Subtotal	8,373
Subtotal		8,403
Non-guaranteed separate accounts priced at NAV as a practical expedient	842
Non-guaranteed separate accounts priced at NAV as a practical expedient		683
Total	9,215
Separate account assets of business classified as held for sale	(878)
Separate account assets per Consolidated Balance Sheets	8,337	9,086
Pension Plan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-guaranteed separate accounts	4,500
Non-guaranteed separate accounts		4,200
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	227
Guaranteed separate accounts		226
Non-guaranteed separate accounts	1,130
Non-guaranteed separate accounts		1,925
Subtotal	1,357
Subtotal		2,151
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Guaranteed separate accounts	276
Guaranteed separate accounts		297
Non-guaranteed separate accounts	6,406
Non-guaranteed separate accounts		5,600
Subtotal	6,682
Subtotal		5,897
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Guaranteed separate accounts	0
Guaranteed separate accounts		0
Non-guaranteed separate accounts	334
Non-guaranteed separate accounts		355
Subtotal	334
Subtotal		355
Significant Unobservable Inputs (Level 3) | Pension Plan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-guaranteed separate accounts	$ 300
Non-guaranteed separate accounts		$ 300