Schedule I (Details) $ in Millions	Dec. 31, 2024 USD ($)
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	$ 96,019
Fair value	93,547
Amount at which shown in the Balance sheet	93,663
U.S. government and government sponsored entities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	3,346
Fair value	3,267
Amount at which shown in the Balance sheet	3,267
Obligations of states, municipalities and political subdivisions
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	3,273
Fair value	3,193
Amount at which shown in the Balance sheet	3,193
Non-U.S. governments
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	8,668
Fair value	8,131
Amount at which shown in the Balance sheet	8,131
Public utilities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	3,253
Fair value	3,053
Amount at which shown in the Balance sheet	3,053
All other corporate debt securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	30,059
Fair value	29,055
Amount at which shown in the Balance sheet	29,055
Mortgage-backed, asset-backed and collateralized
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	18,341
Fair value	18,052
Amount at which shown in the Balance sheet	18,052
Fixed maturity securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	66,940
Fair value	64,751
Amount at which shown in the Balance sheet	64,751
Public utilities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	1
Fair value	1
Amount at which shown in the Balance sheet	1
Banks, trust and insurance companies
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	489
Fair value	489
Amount at which shown in the Balance sheet	489
Industrial, miscellaneous and all other
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	36
Fair value	36
Amount at which shown in the Balance sheet	36
Common Stock, Par Value $2.50 Per Share
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	526
Fair value	526
Amount at which shown in the Balance sheet	526
Mutual funds
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	178
Fair value	178
Amount at which shown in the Balance sheet	178
Equity Securities And Mutual Funds
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	704
Fair value	704
Amount at which shown in the Balance sheet	704
Mortgage and other loans receivable, net of allowance
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	3,868
Fair value	3,752
Amount at which shown in the Balance sheet	3,868
Other invested assets
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	9,995
Fair value	9,828
Amount at which shown in the Balance sheet	9,828
Short-term investments, at cost (approximates fair value)
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	14,462
Fair value	14,462
Amount at which shown in the Balance sheet	14,462
Derivative assets
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	50
Fair value	50
Amount at which shown in the Balance sheet	$ 50