Disposition of Metropolitan Property and Casualty Insurance Company (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and cash equivalents	$ 611	$ 765	$ 0	$ 0
Liabilities held-for-sale	3,865	4,650
Metropolitan Property And Casualty Insurance Company
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Assets	6,599	7,418
Cash and cash equivalents	611	765
Goodwill	328	328
Other assets	153	143
Liabilities held-for-sale	3,865	4,650
Current income tax payable	59	0
Other liabilities	246	249
Metropolitan Property And Casualty Insurance Company | Fixed maturity securities AFS
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Assets	3,544	4,096
Metropolitan Property And Casualty Insurance Company | Equity Securities
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Assets	52	57
Metropolitan Property And Casualty Insurance Company | Mortgages [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Assets	287	355
Metropolitan Property And Casualty Insurance Company | Other invested assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Assets	2	29
Metropolitan Property And Casualty Insurance Company | Investments
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Assets	3,885	4,537
Metropolitan Property And Casualty Insurance Company | Accrued investment income
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Assets	38	38
Metropolitan Property And Casualty Insurance Company | Receivables [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Assets	1,398	1,411
Metropolitan Property And Casualty Insurance Company | Deferred policy acquisition costs
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Assets	186	196
Metropolitan Property And Casualty Insurance Company | Future policy benefits
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Liabilities held-for-sale	3,507	3,506
Metropolitan Property And Casualty Insurance Company | Other Policy-Related Balances
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Liabilities held-for-sale	48	33
Metropolitan Property And Casualty Insurance Company | Payables for collateral under securities loaned and other transactions
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Liabilities held-for-sale	0	862
Metropolitan Property And Casualty Insurance Company | Deferred income tax liability
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Liabilities held-for-sale	$ 5	$ 0