SCHEDULE I - 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	$ 66,612
Fair Value	68,953
Carrying Value	68,098
U.S. Treasury, government and agency
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	12,644
Fair Value	13,135
Carrying Value	13,135
States and political subdivisions
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	414
Fair Value	481
Carrying Value	481
Foreign governments
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	376
Fair Value	396
Carrying Value	396
Public utilities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	3,540
Fair Value	3,728
Carrying Value	3,728
All other corporate bonds
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	17,083
Fair Value	17,784
Carrying Value	17,784
Residential mortgage-backed
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	236
Fair Value	251
Carrying Value	251
Asset-backed
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	89
Fair Value	92
Carrying Value	92
Redeemable preferred stock
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	449
Fair Value	491
Carrying Value	491
Fixed maturities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	34,831
Fair Value	36,358
Carrying Value	36,358
Mortgage loans on real estate
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	10,943
Fair Value	10,895
Carrying Value	10,935
Real estate held for the production of income
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	390
Fair Value	390
Carrying Value	390
Policy loans
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	3,315
Fair Value	4,210
Carrying Value	3,315
Other equity investments
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,351
Fair Value	1,351
Carrying Value	1,351
Trading securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	12,661
Fair Value	12,628
Carrying Value	12,628
Other invested assets
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	3,121
Fair Value	3,121
Carrying Value	$ 3,121