Schedule I Summary of Investments - Other than Investments in Related Parties (Details) $ in Millions	Dec. 31, 2016 USD ($)
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	$ 320,118
Fair Value	330,026
Amount at which shown in the Balance Sheet	329,984
Fixed maturity securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	246,239
Fair Value	255,535
Amount at which shown in the Balance Sheet	255,535
U.S. government and government sponsored entities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	4,809
Fair Value	4,932
Amount at which shown in the Balance Sheet	4,932
Obligations of states, municipalities and political subdivisions
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	24,026
Fair Value	24,772
Amount at which shown in the Balance Sheet	24,772
Non-U.S. government
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	14,068
Fair Value	14,585
Amount at which shown in the Balance Sheet	14,585
Public utilities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	17,094
Fair Value	18,018
Amount at which shown in the Balance Sheet	18,018
All other corporate and debt securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	111,326
Fair Value	115,934
Amount at which shown in the Balance Sheet	115,934
Mortgage-backed, asset-backed and collateralized
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	74,916
Fair Value	77,294
Amount at which shown in the Balance Sheet	77,294
Equity securities and mutual funds
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	2,179
Fair Value	2,560
Amount at which shown in the Balance Sheet	2,560
Common Stock
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,148
Fair Value	1,506
Amount at which shown in the Balance Sheet	1,506
Public utilities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	3
Fair Value	4
Amount at which shown in the Balance Sheet	4
Banks, trust and insurance companies
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	900
Fair Value	1,108
Amount at which shown in the Balance Sheet	1,108
Industrial, miscellaneous and all other
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	245
Fair Value	394
Amount at which shown in the Balance Sheet	394
Preferred stock
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	748
Fair Value	752
Amount at which shown in the Balance Sheet	752
Mutual funds
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	283
Fair Value	302
Amount at which shown in the Balance Sheet	302
Mortgage and other loans receivable, net of allowance
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	33,240
Fair Value	33,747
Amount at which shown in the Balance Sheet	33,240
Other invested assets
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	24,349
Fair Value	24,073
Amount at which shown in the Balance Sheet	24,538
Short-term investments, at cost
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	12,302
Fair Value	12,302
Amount at which shown in the Balance Sheet	12,302
Derivative assets
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,809
Fair Value	1,809
Amount at which shown in the Balance Sheet	$ 1,809