Investments - Amortized Cost and Fair Value of Fixed Maturity Available-for-Sale Securities (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Due in one year or less, Amortized Cost	$ 417
Due after one year through five years, Amortized Cost	2,104
Due after five years through ten years, Amortized Cost	2,236
Due after ten years, Amortized Cost	10,776
Subtotal, Amortized Cost	15,533
Other securities which provide for periodic payments, Amortized Cost	8,912
Amortized Cost	24,445	$ 2,029
Due in one year or less, Fair Value	416
Due after one year through five years, Fair Value	2,164
Due after five years through ten years, Fair Value	2,307
Due after ten years, Fair Value	11,080
Subtotal, Fair Value	15,967
Other securities which provide for periodic payments, Fair Value	9,147
Total fixed maturity available-for-sale securities, Fair Value	25,114
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Other securities which provide for periodic payments, Amortized Cost	5,501
Amortized Cost	5,501
Other securities which provide for periodic payments, Fair Value	5,610
Commercial mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Other securities which provide for periodic payments, Amortized Cost	2,444
Amortized Cost	2,444	$ 22
Other securities which provide for periodic payments, Fair Value	2,582
Structured hybrids
Debt Securities, Available-for-sale [Line Items]
Other securities which provide for periodic payments, Amortized Cost	26
Other securities which provide for periodic payments, Fair Value	28
Residential mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Other securities which provide for periodic payments, Amortized Cost	941
Other securities which provide for periodic payments, Fair Value	$ 927