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
Cost/amortized cost	$ 80,022
Amount at which shown in the Balance Sheet	81,799
United States government, government agencies and authorities
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	3,572
Fair value	3,637
Amount at which shown in the Balance Sheet	3,637
States, municipalities and political subdivisions
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	7,116
Fair value	7,333
Amount at which shown in the Balance Sheet	7,333
Foreign governments
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	1,043
Fair value	1,075
Amount at which shown in the Balance Sheet	1,075
Public utilities
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	5,048
Fair value	5,322
Amount at which shown in the Balance Sheet	5,322
All other corporate bonds
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	37,694
Fair value	38,279
Amount at which shown in the Balance Sheet	38,279
Asset-backed securities
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	1,169
Fair value	1,171
Amount at which shown in the Balance Sheet	1,171
Residential mortgage-backed securities
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	651
Fair value	728
Amount at which shown in the Balance Sheet	728
Commercial mortgage-backed securities
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	262
Fair value	270
Amount at which shown in the Balance Sheet	270
Redeemable preferred stock
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	21
Fair value	24
Amount at which shown in the Balance Sheet	24
Fixed income securities
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	56,576
Fair value	57,839
Amount at which shown in the Balance Sheet	57,839
Public utilities
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	108
Fair value	114
Amount at which shown in the Balance Sheet	114
Banks, trusts and insurance companies
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	804
Fair value	895
Amount at which shown in the Balance Sheet	895
Industrial, miscellaneous and all other
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	4,100
Fair value	4,477
Amount at which shown in the Balance Sheet	4,477
Nonredeemable preferred stocks
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	145
Fair value	180
Amount at which shown in the Balance Sheet	180
Equity securities
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	5,157
Fair value	5,666
Amount at which shown in the Balance Sheet	5,666
Mortgage loans on real estate
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	4,486
Fair value	4,514
Amount at which shown in the Balance Sheet	4,486
Real estate
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	318
Amount at which shown in the Balance Sheet	318
Real estate acquired in satisfaction of debt
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	0
Amount at which shown in the Balance Sheet	0
Policy loans
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	904
Amount at which shown in the Balance Sheet	904
Derivative instruments
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	106
Fair value	111
Amount at which shown in the Balance Sheet	111
Limited partnership interests
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	5,814
Amount at which shown in the Balance Sheet	5,814
Other long-term investments
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	2,373
Amount at which shown in the Balance Sheet	2,373
Short-term investments
Summary of Investments Other Than Investments in Related Parties
Cost/amortized cost	4,288
Fair value	4,288
Amount at which shown in the Balance Sheet	$ 4,288