Disposition of Metropolitan Property and Casualty Insurance Company (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Assets	$ 7,462		$ 0
Cash and cash equivalents	103	$ 765	0	$ 0
Liabilities held-for-sale	$ 6,757	4,650	$ 0
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		7,418
Cash and cash equivalents		765
Goodwill		328
Other assets		143
Liabilities held-for-sale		4,650
Other liabilities		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		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		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		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		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		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
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		1,411
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		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		3,506
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		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		$ 862