Schedule I - Summary of Investments Other than Investments in Affiliates (Details) $ in Millions	Dec. 31, 2019 USD ($)
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	$ 49,434
Fair Value	54,142
Amount Shown on Consolidated Balance Sheet	53,687
U.S. Treasuries
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	1,074
Fair Value	1,382
Amount Shown on Consolidated Balance Sheet	1,382
U.S. Government agencies and authorities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	74
Fair Value	95
Amount Shown on Consolidated Balance Sheet	95
State, municipalities, and political subdivisions
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	1,220
Fair Value	1,323
Amount Shown on Consolidated Balance Sheet	1,323
U.S. corporate public securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	12,980
Fair Value	14,938
Amount Shown on Consolidated Balance Sheet	14,938
U.S. corporate private securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	5,568
Fair Value	6,035
Amount Shown on Consolidated Balance Sheet	6,035
Foreign corporate public securities and foreign governments(1)
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	3,887
Fair Value	4,341
Amount Shown on Consolidated Balance Sheet	4,341
Foreign corporate private securities(1)
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	4,545
Fair Value	4,831
Amount Shown on Consolidated Balance Sheet	4,831
Residential mortgage-backed securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	4,999
Fair Value	5,204
Amount Shown on Consolidated Balance Sheet	5,204
Commercial mortgage-backed securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	3,402
Fair Value	3,574
Amount Shown on Consolidated Balance Sheet	3,574
Other asset-backed securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	2,058
Fair Value	2,055
Amount Shown on Consolidated Balance Sheet	2,055
Fixed maturities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	39,807
Fair Value	43,778
Amount Shown on Consolidated Balance Sheet	43,778
Equity securities, available-for-sale
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	196
Fair Value	196
Amount Shown on Consolidated Balance Sheet	196
Short-term investments
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	68
Fair Value	68
Amount Shown on Consolidated Balance Sheet	68
Mortgage loans on real estate
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	6,878
Fair Value	7,262
Amount Shown on Consolidated Balance Sheet	6,878
Policy loans
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	776
Fair Value	776
Amount Shown on Consolidated Balance Sheet	776
Limited partnerships/corporations
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	1,290
Fair Value	1,290
Amount Shown on Consolidated Balance Sheet	1,290
Derivatives
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	34
Fair Value	316
Amount Shown on Consolidated Balance Sheet	316
Other investments
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	385
Fair Value	456
Amount Shown on Consolidated Balance Sheet	$ 385