Schedule I Summary of Investments - Other than Investments in Related Parties (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Summary of Investments Other than Investments in Related Parties
Cost	$ 353,253
Fair Value	377,960
Amount at which shown in the Balance Sheet	379,495
Fixed maturity securities
Summary of Investments Other than Investments in Related Parties
Cost	270,733
Fair Value	294,543
Amount at which shown in the Balance Sheet	294,543
U.S. government and government sponsored entities
Summary of Investments Other than Investments in Related Parties
Cost	9,955
Fair Value	10,277
Amount at which shown in the Balance Sheet	10,277
Obligations of states, municipalities and political subdivisions
Summary of Investments Other than Investments in Related Parties
Cost	33,042
Fair Value	35,705
Amount at which shown in the Balance Sheet	35,705
Non-U.S. government
Summary of Investments Other than Investments in Related Parties
Cost	25,451
Fair Value	26,802
Amount at which shown in the Balance Sheet	26,802
Public utilities
Summary of Investments Other than Investments in Related Parties
Cost	22,266
Fair Value	24,993
Amount at which shown in the Balance Sheet	24,993
All other corporate and debt securities
Summary of Investments Other than Investments in Related Parties
Cost	114,782
Fair Value	127,439
Amount at which shown in the Balance Sheet	127,439
Mortgage-backed, asset-backed and collateralized
Summary of Investments Other than Investments in Related Parties
Cost	65,237
Fair Value	69,327
Amount at which shown in the Balance Sheet	69,327
Equity securities and mutual funds
Summary of Investments Other than Investments in Related Parties
Cost	2,302
Fair Value	3,874
Amount at which shown in the Balance Sheet	3,874
Common stock
Summary of Investments Other than Investments in Related Parties
Cost	2,141
Fair Value	3,678
Amount at which shown in the Balance Sheet	3,678
Public utilities
Summary of Investments Other than Investments in Related Parties
Cost	9
Fair Value	11
Amount at which shown in the Balance Sheet	11
Banks, trust and insurance companies
Summary of Investments Other than Investments in Related Parties
Cost	1,579
Fair Value	3,036
Amount at which shown in the Balance Sheet	3,036
Industrial, miscellaneous and all other
Summary of Investments Other than Investments in Related Parties
Cost	553
Fair Value	631
Amount at which shown in the Balance Sheet	631
Preferred stock
Summary of Investments Other than Investments in Related Parties
Cost	56
Fair Value	78
Amount at which shown in the Balance Sheet	78
Mutual funds
Summary of Investments Other than Investments in Related Parties
Cost	105
Fair Value	118
Amount at which shown in the Balance Sheet	118
Mortgage and other loans receivable, net of allowance
Summary of Investments Other than Investments in Related Parties
Cost	19,482
Fair Value	20,353
Amount at which shown in the Balance Sheet	19,482
Other invested assets
Summary of Investments Other than Investments in Related Parties
Cost	28,257
Fair Value	26,711
Amount at which shown in the Balance Sheet	29,117
Short-term investments, at cost (approximates fair value)
Summary of Investments Other than Investments in Related Parties
Cost	28,808
Fair Value	28,808
Amount at which shown in the Balance Sheet	28,808
Derivative assets
Summary of Investments Other than Investments in Related Parties
Cost	3,671
Fair Value	3,671
Amount at which shown in the Balance Sheet	$ 3,671