Consolidated Summary of Investments - Other Than Investments in Related Parties (Details) $ in Millions	Dec. 31, 2017 USD ($)
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	$ 418,743
Estimated Fair Value	444,067
Fixed Maturities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	286,069
Estimated Fair Value	308,931
Amount at Which Shown on Balance Sheet	308,931
Foreign government
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	55,351
Estimated Fair Value	61,534
Amount at Which Shown on Balance Sheet	61,534
U.S. government and agency
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	43,446
Estimated Fair Value	47,394
Amount at Which Shown on Balance Sheet	47,394
Public utilities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	12,087
Estimated Fair Value	13,581
Amount at Which Shown on Balance Sheet	13,581
State and political subdivision
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	10,752
Estimated Fair Value	12,455
Amount at Which Shown on Balance Sheet	12,455
All other corporate bonds
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	115,238
Estimated Fair Value	123,445
Amount at Which Shown on Balance Sheet	123,445
Total bonds
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	236,874
Estimated Fair Value	258,409
Amount at Which Shown on Balance Sheet	258,409
Mortgage-backed and asset-backed securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	48,106
Estimated Fair Value	49,318
Amount at Which Shown on Balance Sheet	49,318
Redeemable preferred stock
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	1,089
Estimated Fair Value	1,204
Amount at Which Shown on Balance Sheet	1,204
FVO securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	14,656
Estimated Fair Value	16,745
Amount at Which Shown on Balance Sheet	16,745
Equity Securities, Investment Summary [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	2,140
Estimated Fair Value	2,513
Amount at Which Shown on Balance Sheet	2,513
Industrial, miscellaneous and all other
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	1,538
Estimated Fair Value	1,807
Amount at Which Shown on Balance Sheet	1,807
Public utilities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	66
Estimated Fair Value	74
Amount at Which Shown on Balance Sheet	74
Banks, trust and insurance companies
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	83
Estimated Fair Value	154
Amount at Which Shown on Balance Sheet	154
Non-redeemable preferred stock
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	453
Estimated Fair Value	478
Amount at Which Shown on Balance Sheet	478
Held-for-investment
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	68,731
Estimated Fair Value	68,731
Policy loans
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	9,669
Estimated Fair Value	9,669
Real estate and real estate joint ventures
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	9,589
Estimated Fair Value	9,589
Real estate acquired in satisfaction of debt
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	48
Estimated Fair Value	48
Other limited partnership interests
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	5,708
Estimated Fair Value	5,708
Short-term investments
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	4,870
Estimated Fair Value	4,870
Other invested assets
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	17,263
Estimated Fair Value	$ 17,263