Schedule I (Details) $ in Millions	Dec. 31, 2023 USD ($)
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	$ 345,335
Fair value	320,166
Amount at which shown in the Balance sheet	323,183
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	5,885
Fair value	5,616
Amount at which shown in the Balance sheet	5,616
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	11,479
Fair value	10,754
Amount at which shown in the Balance sheet	10,754
Non-U.S. governments
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	13,705
Fair value	12,490
Amount at which shown in the Balance sheet	12,490
Public utilities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	23,336
Fair value	20,088
Amount at which shown in the Balance sheet	20,088
All other corporate debt securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	134,244
Fair value	121,252
Amount at which shown in the Balance sheet	121,252
Mortgage-backed, asset-backed and collateralized
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	69,624
Fair value	66,774
Amount at which shown in the Balance sheet	66,774
Fixed maturity securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	258,273
Fair value	236,974
Amount at which shown in the Balance sheet	236,974
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	441
Fair value	441
Amount at which shown in the Balance sheet	441
Industrial, miscellaneous and all other
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	77
Fair value	77
Amount at which shown in the Balance sheet	77
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	519
Fair value	519
Amount at which shown in the Balance sheet	519
Preferred stock
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	57
Fair value	57
Amount at which shown in the Balance sheet	57
Mutual funds
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	152
Fair value	152
Amount at which shown in the Balance sheet	152
Equity Securities And Mutual Funds
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	728
Fair value	728
Amount at which shown in the Balance sheet	728
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	51,553
Fair value	48,536
Amount at which shown in the Balance sheet	51,553
Other invested assets
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	17,070
Fair value	16,217
Amount at which shown in the Balance sheet	16,217
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	17,200
Fair value	17,200
Amount at which shown in the Balance sheet	17,200
Derivative assets
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	511
Fair value	511
Amount at which shown in the Balance sheet	$ 511