Consolidated Summary of Investments - Other Than Investments in Related Parties (Details) $ in Millions	Dec. 31, 2019 USD ($)
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	$ 86,844
Amount at Which Shown on Balance Sheet	93,748
U.S. government and agency
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	5,396
Estimated Fair Value	7,244
Amount at Which Shown on Balance Sheet	7,244
State and political subdivision
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	3,326
Estimated Fair Value	4,011
Amount at Which Shown on Balance Sheet	4,011
Public utilities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	3,270
Estimated Fair Value	3,703
Amount at Which Shown on Balance Sheet	3,703
Foreign government
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	1,503
Estimated Fair Value	1,751
Amount at Which Shown on Balance Sheet	1,751
All other corporate bonds
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	33,243
Estimated Fair Value	36,215
Amount at Which Shown on Balance Sheet	36,215
Total bonds
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	46,738
Estimated Fair Value	52,924
Amount at Which Shown on Balance Sheet	52,924
Mortgage-backed and asset-backed securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	16,000
Estimated Fair Value	16,694
Amount at Which Shown on Balance Sheet	16,694
Redeemable preferred stock
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	345
Estimated Fair Value	359
Amount at Which Shown on Balance Sheet	359
Total fixed maturity securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	63,083
Estimated Fair Value	69,977
Amount at Which Shown on Balance Sheet	69,977
Non-redeemable preferred stock
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	127
Estimated Fair Value	129
Amount at Which Shown on Balance Sheet	129
Industrial, miscellaneous and all other
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	10
Estimated Fair Value	15
Amount at Which Shown on Balance Sheet	15
Public utilities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	0
Estimated Fair Value	3
Amount at Which Shown on Balance Sheet	3
Total equity securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	137
Estimated Fair Value	147
Amount at Which Shown on Balance Sheet	147
Mortgage loans
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	15,664
Amount at Which Shown on Balance Sheet	15,664
Policy loans
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	875
Amount at Which Shown on Balance Sheet	875
Limited partnerships and LLCs
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	2,379
Amount at Which Shown on Balance Sheet	2,379
Short-term investments
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	1,482
Amount at Which Shown on Balance Sheet	1,482
Other invested assets
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	3,224
Amount at Which Shown on Balance Sheet	$ 3,224