Schedule I Summary of Investments - Other than Investments in Related Parties (Details) $ in Millions	Dec. 31, 2020 USD ($)
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	$ 335,039
Fair Value	364,516
Amount at which shown in the Balance Sheet	361,442
Fixed maturity securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	249,628
Fair Value	276,787
Amount at which shown in the Balance Sheet	276,787
U.S. government and government sponsored entities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	5,485
Fair Value	5,971
Amount at which shown in the Balance Sheet	5,971
Obligations of states, municipalities and political subdivisions
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	13,915
Fair Value	16,124
Amount at which shown in the Balance Sheet	16,124
Non-U.S. government
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	14,231
Fair Value	15,345
Amount at which shown in the Balance Sheet	15,345
Public utilities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	20,567
Fair Value	23,420
Amount at which shown in the Balance Sheet	23,420
All other corporate and debt securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	129,556
Fair Value	145,890
Amount at which shown in the Balance Sheet	145,890
Mortgage-backed, asset-backed and collateralized
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	65,874
Fair Value	70,037
Amount at which shown in the Balance Sheet	70,037
Equity securities and mutual funds
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,056
Fair Value	1,056
Amount at which shown in the Balance Sheet	1,056
Common Stock
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	767
Fair Value	767
Amount at which shown in the Balance Sheet	767
Public utilities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1
Fair Value	1
Amount at which shown in the Balance Sheet	1
Banks, trust and insurance companies
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	187
Fair Value	187
Amount at which shown in the Balance Sheet	187
Industrial, miscellaneous and all other
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	579
Fair Value	579
Amount at which shown in the Balance Sheet	579
Preferred stock
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	13
Fair Value	13
Amount at which shown in the Balance Sheet	13
Mutual funds
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	276
Fair Value	276
Amount at which shown in the Balance Sheet	276
Mortgage and other loans receivable, net of allowance
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	45,562
Fair Value	48,636
Amount at which shown in the Balance Sheet	45,562
Other invested assets
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	19,816
Fair Value	19,060
Amount at which shown in the Balance Sheet	19,060
Short-term investments, at cost
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	18,203
Fair Value	18,203
Amount at which shown in the Balance Sheet	18,203
Derivative assets
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	774
Fair Value	774
Amount at which shown in the Balance Sheet	$ 774