Schedule I Summary of Investments - Other Than Investments in Affiliates Level 4 (Details) $ in Millions	Dec. 31, 2015 USD ($)
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	$ 70,996
Amount which shown on Balance Sheet	72,728
Fixed Maturities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	57,475
Fair Value	59,699
Amount which shown on Balance Sheet	59,699
Industrial, miscellaneous and all other [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	969
Fair Value	956
Amount which shown on Balance Sheet	956
Non-redeemable preferred stocks [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	166
Fair Value	165
Amount which shown on Balance Sheet	165
Equity Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,145
Fair Value	1,132
Amount which shown on Balance Sheet	1,132
Mortgage loans [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	5,624
Fair Value	5,736
Amount which shown on Balance Sheet	5,624
Policy Loans [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,447
Fair Value	1,447
Amount which shown on Balance Sheet	1,447
Investments in partnerships and trusts [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	$ 2,874
Fair Value
Amount which shown on Balance Sheet	$ 2,874
Futures Options and Miscellaneous [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	588
Fair Value	109
Amount which shown on Balance Sheet	109
Short-term Investments [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,843
Fair Value	1,843
Amount which shown on Balance Sheet	1,843
Trading Securities [Member] | Equity Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	10
Fair Value	11
Amount which shown on Balance Sheet	11
Available-for-sale Securities [Member] | Equity Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,135
Fair Value	1,121
Amount which shown on Balance Sheet	1,121
Available-for-sale Securities [Member] | Fixed Maturities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	510
Fair Value	503
Amount which shown on Balance Sheet	503
Portion at Fair Value Measurement [Member] | U.S. government and government agencies and authorities (guaranteed and sponsored) [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	7,911
Fair Value	8,179
Amount which shown on Balance Sheet	8,179
Portion at Fair Value Measurement [Member] | US States and Political Subdivisions Debt Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	11,124
Fair Value	12,121
Amount which shown on Balance Sheet	12,121
Portion at Fair Value Measurement [Member] | Foreign governments [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,321
Fair Value	1,308
Amount which shown on Balance Sheet	1,308
Portion at Fair Value Measurement [Member] | Public utilities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	4,395
Fair Value	4,634
Amount which shown on Balance Sheet	4,634
Portion at Fair Value Measurement [Member] | All other corporate bonds [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	21,481
Fair Value	22,168
Amount which shown on Balance Sheet	22,168
Portion at Fair Value Measurement [Member] | All Other Mortgage Backed and Asset Backed Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	10,733
Fair Value	10,786
Amount which shown on Balance Sheet	10,786
Portion at Fair Value Measurement [Member] | Available-for-sale Securities [Member] | Fixed Maturities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	56,965
Fair Value	59,196
Amount which shown on Balance Sheet	$ 59,196