Variable Annuity and Insurance Guarantees (Liability Rollforward) (Details 4) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
GMDB and GGU [Member]
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Gross
Balance, at the beginning of the period		$ 16	$ 14	$ 9
Incurred claims		5	11	10
Paid claims		(4)	(9)	(5)
Balance, at the end of the period		17	16	14
GMIB [Member]
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Gross
Balance, at the beginning of the period		8	8	7
Incurred claims			1	1
Paid claims		(2)	(1)
Balance, at the end of the period		6	8	8
GMWB [Member]
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Gross
Balance, at the beginning of the period	[1]	1,017	1,057	693
Incurred claims	[1]	(554)	(40)	364
Balance, at the end of the period	[1]	463	1,017	1,057
GMAB [Member]
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Gross
Balance, at the beginning of the period	[1]	(24)	0	(41)
Incurred claims	[1]	(56)	(23)	41
Paid claims	[1]		(1)
Balance, at the end of the period	[1]	(80)	(24)	0
UL [Member]
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Gross
Balance, at the beginning of the period		434	332	263
Incurred claims		84	127	92
Paid claims		(29)	(25)	(23)
Balance, at the end of the period		$ 489	$ 434	$ 332

[1] The incurred claims for GMWB and GMAB represent the change in the fair value of the liabilities (contra liabilities) less paid claims.