Reserve for Life-Contingent Contract Benefits and Contractholder Funds - Liabilities for guarantees narrative (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Liabilities for guarantees:
Liability for guarantees	$ 418	$ 443	$ 369
Variable annuities | In the event of death
Liabilities for guarantees:
Liability for guarantees	78	109	85
Variable annuities | Liability for guarantees related to income benefits
Liabilities for guarantees:
Liability for guarantees	21	36	26
Variable annuities | Guaranteed accumulation benefits
Liabilities for guarantees:
Liability for guarantees	18	25	22
Variable annuities | For cumulative periodic withdrawals
Liabilities for guarantees:
Liability for guarantees	14	14	12
Variable annuities | Other guarantees
Liabilities for guarantees:
Liability for guarantees	$ 287	$ 259	$ 224