Reserve for Life-Contingent Contract Benefits and Contractholder Funds - Liabilities for guarantees (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Liabilities for guarantees:
Liabilities for Guarantees on Long-Duration Contracts, Incurred Benefits	$ 30	$ 37
Movement in Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Gross [Roll Forward]
Balance at beginning of period	443	369
Less reinsurance recoverables	185	146
Net balance at beginning of period	258	223
Paid guarantee benefits	(3)	(2)
Net change	27	35
Net balance at end of period	285	258
Plus reinsurance recoverables	133	185
Balance at end of period	418	443
Liability for guarantees related to death benefits and interest-sensitive life products
Liabilities for guarantees:
Liabilities for Guarantees on Long-Duration Contracts, Incurred Benefits	18	24
Movement in Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Gross [Roll Forward]
Balance at beginning of period	307	261
Less reinsurance recoverables	111	87
Net balance at beginning of period	196	174
Paid guarantee benefits	(3)	(2)
Net change	15	22
Net balance at end of period	211	196
Plus reinsurance recoverables	81	111
Balance at end of period	292	307
Liability for guarantees related to income benefits
Liabilities for guarantees:
Liabilities for Guarantees on Long-Duration Contracts, Incurred Benefits	0	0
Movement in Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Gross [Roll Forward]
Balance at beginning of period	38	28
Less reinsurance recoverables	35	25
Net balance at beginning of period	3	3
Paid guarantee benefits	0	0
Net change	0	0
Net balance at end of period	3	3
Plus reinsurance recoverables	20	35
Balance at end of period	23	38
Liability for guarantees related to accumulation and withdrawal benefits
Liabilities for guarantees:
Liabilities for Guarantees on Long-Duration Contracts, Incurred Benefits	12	13
Movement in Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Gross [Roll Forward]
Balance at beginning of period	98	80
Less reinsurance recoverables	39	34
Net balance at beginning of period	59	46
Paid guarantee benefits	0	0
Net change	12	13
Net balance at end of period	71	59
Plus reinsurance recoverables	32	39
Balance at end of period	$ 103	$ 98