Consolidated Summary of Investments - Other Than Investments in Related Parties (Details) $ in Millions	Dec. 31, 2018 USD ($)
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	$ 423,772
Estimated Fair Value	436,210
Fixed Maturities [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	286,816
Estimated Fair Value	298,265
Amount at Which Shown on Balance Sheet	298,265
Foreign government
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	56,353
Estimated Fair Value	62,288
Amount at Which Shown on Balance Sheet	62,288
U.S. government and agency
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	37,030
Estimated Fair Value	39,322
Amount at Which Shown on Balance Sheet	39,322
Public utilities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	12,430
Estimated Fair Value	13,075
Amount at Which Shown on Balance Sheet	13,075
Municipals
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	10,376
Estimated Fair Value	11,533
Amount at Which Shown on Balance Sheet	11,533
All other corporate bonds
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	120,505
Estimated Fair Value	121,423
Amount at Which Shown on Balance Sheet	121,423
Total bonds
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	236,694
Estimated Fair Value	247,641
Amount at Which Shown on Balance Sheet	247,641
Mortgage-backed and asset-backed securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	49,006
Estimated Fair Value	49,471
Amount at Which Shown on Balance Sheet	49,471
Redeemable preferred stock
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	1,116
Estimated Fair Value	1,153
Amount at Which Shown on Balance Sheet	1,153
Unit-linked and FVO Securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	11,809
Estimated Fair Value	12,616
Amount at Which Shown on Balance Sheet	12,616
Equity Securities, Investment Summary [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	1,258
Estimated Fair Value	1,440
Amount at Which Shown on Balance Sheet	1,440
Industrial, miscellaneous and all other
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	667
Estimated Fair Value	827
Amount at Which Shown on Balance Sheet	827
Public utilities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	102
Estimated Fair Value	91
Amount at Which Shown on Balance Sheet	91
Banks, trust and insurance companies
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	67
Estimated Fair Value	119
Amount at Which Shown on Balance Sheet	119
Non-redeemable preferred stock
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	422
Estimated Fair Value	403
Amount at Which Shown on Balance Sheet	403
Held-for-investment
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	75,752
Estimated Fair Value	75,752
Policy loans
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	9,699
Estimated Fair Value	9,699
Real estate and real estate joint ventures
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	9,653
Estimated Fair Value	9,653
Real estate acquired in satisfaction of debt
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	45
Estimated Fair Value	45
Other limited partnership interests
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	6,613
Estimated Fair Value	6,613
Short-term investments
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	3,937
Estimated Fair Value	3,937
Other invested assets
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	18,190
Estimated Fair Value	$ 18,190