Pending Disposition of Metropolitan Property and Casualty Insurance Company (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 30, 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Assets	$ 7,418	$ 0	$ 0
Cash and Cash Equivalents	765	0	0
Disposal Group, Including Discontinued Operation, Liabilities	4,650	0	0
Income (loss) before provision for income tax and equity in earnings of subsidiaries	6,927	6,795	6,307
Metropolitan Property And Casualty Insurance Company [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Agreed upon proceeds from divestiture of business.				$ 3,900
Disposal Group, Including Discontinued Operation, Assets	7,418
Cash and Cash Equivalents	765
Goodwill	328
Other Assets	143
Disposal Group, Including Discontinued Operation, Liabilities	4,650
Other Liabilities	249
Income (loss) before provision for income tax and equity in earnings of subsidiaries	399	$ 291	$ 367
Metropolitan Property And Casualty Insurance Company [Member] | 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 [Member] | 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 [Member] | 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 [Member] | 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 [Member] | 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 [Member] | 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 [Member] | 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 [Member] | 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 [Member] | Future policy benefits
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Liabilities	3,506
Metropolitan Property And Casualty Insurance Company [Member] | Other Policy-Related Balances
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Liabilities	33
Metropolitan Property And Casualty Insurance Company [Member] | Payables for collateral under securities loaned and other transactions
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Liabilities	$ 862