Consolidated Summary of Investments - Other Than Investments in Related Parties (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	$ 66,236
Amount at Which Shown on Balance Sheet	68,729
Other Investments	3,887	$ 4,942
Short-term investments	926	1,737
Other Limited Partnership Interests	1,639	1,846
Real Estate Investments, Net	215	628
Loans, Gross, Insurance Policy	1,093	1,266
Mortgage Loans on Real Estate	8,884	$ 7,262
Fixed Maturities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	49,312
Estimated Fair Value	51,785
Amount at Which Shown on Balance Sheet	51,785
U.S. government and agency securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	10,517
Estimated Fair Value	11,550
Amount at Which Shown on Balance Sheet	11,550
State and political subdivision securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	2,633
Estimated Fair Value	2,914
Amount at Which Shown on Balance Sheet	2,914
Public utilities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	1,637
Estimated Fair Value	1,815
Amount at Which Shown on Balance Sheet	1,815
Foreign government
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	946
Estimated Fair Value	1,046
Amount at Which Shown on Balance Sheet	1,046
All other corporate bonds
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	21,214
Estimated Fair Value	21,912
Amount at Which Shown on Balance Sheet	21,912
Total bonds
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	36,947
Estimated Fair Value	39,237
Amount at Which Shown on Balance Sheet	39,237
Mortgage-backed and asset-backed securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	12,121
Estimated Fair Value	12,214
Amount at Which Shown on Balance Sheet	12,214
Redeemable preferred stock
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	244
Estimated Fair Value	334
Amount at Which Shown on Balance Sheet	334
Equity Securities, Investment Summary [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	280
Estimated Fair Value	300
Amount at Which Shown on Balance Sheet	300
Industrial, miscellaneous and all other
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	98
Estimated Fair Value	116
Amount at Which Shown on Balance Sheet	116
Public utilities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	0
Estimated Fair Value	2
Amount at Which Shown on Balance Sheet	2
Banks, Trust and Insurance, Equities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	2
Estimated Fair Value	5
Amount at Which Shown on Balance Sheet	5
Non-redeemable preferred stock
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	180
Estimated Fair Value	177
Amount at Which Shown on Balance Sheet	177
Mortgage loans
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Amount at Which Shown on Balance Sheet	8,884
Policy loans
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Amount at Which Shown on Balance Sheet	1,093
Real estate and real estate joint ventures
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Amount at Which Shown on Balance Sheet	215
Other limited partnership interests
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Amount at Which Shown on Balance Sheet	1,639
Short-term investments
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Amount at Which Shown on Balance Sheet	926
Other invested assets
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Amount at Which Shown on Balance Sheet	$ 3,887