SCHEDULE I - SUMMARY OF INVESTMENTS OTHER THAN INVESTMENTS IN RELATED PARTIES (Details) $ in Millions	Dec. 31, 2015 USD ($)
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	$ 76,729
Amount at which shown in the Balance Sheet	77,758
United States government, government agencies and authorities
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	3,836
Fair value	3,922
Amount at which shown in the Balance Sheet	3,922
States, municipalities and political subdivisions
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	7,032
Fair value	7,401
Amount at which shown in the Balance Sheet	7,401
Foreign governments
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	983
Fair value	1,033
Amount at which shown in the Balance Sheet	1,033
Public utilities
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	4,605
Fair value	4,864
Amount at which shown in the Balance Sheet	4,864
All other corporate bonds
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	37,069
Fair value	36,963
Amount at which shown in the Balance Sheet	36,963
Asset-backed securities
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	2,359
Fair value	2,327
Amount at which shown in the Balance Sheet	2,327
Residential mortgage-backed securities
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	857
Fair value	947
Amount at which shown in the Balance Sheet	947
Commercial mortgage-backed securities
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	438
Fair value	466
Amount at which shown in the Balance Sheet	466
Redeemable preferred stock
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	22
Fair value	25
Amount at which shown in the Balance Sheet	25
Fixed income securities
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	57,201
Fair value	57,948
Amount at which shown in the Balance Sheet	57,948
Public utilities
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	109
Fair value	111
Amount at which shown in the Balance Sheet	111
Banks, trusts and insurance companies
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	1,160
Fair value	1,193
Amount at which shown in the Balance Sheet	1,193
Industrial, miscellaneous and all other
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	3,453
Fair value	3,672
Amount at which shown in the Balance Sheet	3,672
Nonredeemable preferred stocks
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	84
Fair value	106
Amount at which shown in the Balance Sheet	106
Equity securities
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	4,806
Fair value	5,082
Amount at which shown in the Balance Sheet	5,082
Mortgage loans on real estate
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	4,338
Fair value	4,489
Amount at which shown in the Balance Sheet	4,338
Real estate
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	245
Amount at which shown in the Balance Sheet	245
Real estate acquired in satisfaction of debt
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	6
Amount at which shown in the Balance Sheet	6
Policy loans
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	905
Amount at which shown in the Balance Sheet	905
Derivative instruments
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	47
Fair value	53
Amount at which shown in the Balance Sheet	53
Limited partnership interests
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	4,874
Amount at which shown in the Balance Sheet	4,874
Other long-term investments
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	2,191
Amount at which shown in the Balance Sheet	2,191
Short-term investments
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	2,122
Fair value	2,122
Amount at which shown in the Balance Sheet	$ 2,122