Consolidated Summary of Investments Other Than Investments in Related Parties (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011
Consolidated Summary of Investments - Other Than Investments In Related Parties [Abstract]
Cost or Amortized Cost	$ 40,099
Fair Value	42,769
Amount at which Shown in the Balance Sheet	42,769
Short term investments [Member]
Consolidated Summary of Investments - Other Than Investments In Related Parties [Abstract]
Cost or Amortized Cost	1,893
Fair Value	1,893
Amount at which Shown in the Balance Sheet	1,893
Fixed Maturities [Member]
Consolidated Summary of Investments - Other Than Investments In Related Parties [Abstract]
Cost or Amortized Cost	34,762
Fair Value	37,184
Amount at which Shown in the Balance Sheet	37,184
States, municipalities and political subdivisions [Member]
Consolidated Summary of Investments - Other Than Investments In Related Parties [Abstract]
Cost or Amortized Cost	19,055
Fair Value	20,492
Amount at which Shown in the Balance Sheet	20,492
Foreign government and government agencies [Member]
Consolidated Summary of Investments - Other Than Investments In Related Parties [Abstract]
Cost or Amortized Cost	6,409
Fair Value	6,823
Amount at which Shown in the Balance Sheet	6,823
Public utilities, Bonds [Member]
Consolidated Summary of Investments - Other Than Investments In Related Parties [Abstract]
Cost or Amortized Cost	924
Fair Value	1,023
Amount at which Shown in the Balance Sheet	1,023
Equity securities [Member]
Consolidated Summary of Investments - Other Than Investments In Related Parties [Abstract]
Cost or Amortized Cost	1,264
Fair Value	1,512
Amount at which Shown in the Balance Sheet	1,512
All other corporate bonds [Member]
Consolidated Summary of Investments - Other Than Investments In Related Parties [Abstract]
Cost or Amortized Cost	7,160
Fair Value	7,551
Amount at which Shown in the Balance Sheet	7,551
Public utilities, Equities [Member]
Consolidated Summary of Investments - Other Than Investments In Related Parties [Abstract]
Cost or Amortized Cost	114
Fair Value	157
Amount at which Shown in the Balance Sheet	157
Banks, trusts and insurance companies [Member]
Consolidated Summary of Investments - Other Than Investments In Related Parties [Abstract]
Cost or Amortized Cost	303
Fair Value	278
Amount at which Shown in the Balance Sheet	278
Industrial, miscellaneous and other [Member]
Consolidated Summary of Investments - Other Than Investments In Related Parties [Abstract]
Cost or Amortized Cost	837
Fair Value	1,065
Amount at which Shown in the Balance Sheet	1,065
Non-redeemable preferred stocks [Member]
Consolidated Summary of Investments - Other Than Investments In Related Parties [Abstract]
Cost or Amortized Cost	10
Fair Value	12
Amount at which Shown in the Balance Sheet	12
Common stocks [Member]
Consolidated Summary of Investments - Other Than Investments In Related Parties [Abstract]
Cost or Amortized Cost	1,254
Fair Value	1,500
Amount at which Shown in the Balance Sheet	1,500
Other invested assets [Member]
Consolidated Summary of Investments - Other Than Investments In Related Parties [Abstract]
Cost or Amortized Cost	2,180
Fair Value	2,180
Amount at which Shown in the Balance Sheet	2,180
United States Government and government agencies and authorities [Member]
Consolidated Summary of Investments - Other Than Investments In Related Parties [Abstract]
Cost or Amortized Cost	1,214
Fair Value	1,295
Amount at which Shown in the Balance Sheet	$ 1,295