Variable Annuity and Insurance Guarantees (Liability Rollforward) (Details) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016
GMDB and GGU [Member]
Changes in Additional Liabilities for Variable Annuity and Insurance Guarantees
Balance, at the beginning of the period		$ 16	$ 14
Incurred claims		3	10
Paid claims		(3)	(7)
Balance, at the end of the period		16	17
GMIB [Member]
Changes in Additional Liabilities for Variable Annuity and Insurance Guarantees
Balance, at the beginning of the period		8	8
Paid claims		(1)
Balance, at the end of the period		7	8
GMWB [Member]
Changes in Additional Liabilities for Variable Annuity and Insurance Guarantees
Balance, at the beginning of the period	[1]	1,017	1,057
Incurred claims	[1]	(478)	1,056
Balance, at the end of the period	[1]	539	2,113
GMAB [Member]
Changes in Additional Liabilities for Variable Annuity and Insurance Guarantees
Balance, at the beginning of the period	[1]	(24)
Incurred claims	[1]	(49)	9
Paid claims	[1]		(1)
Balance, at the end of the period	[1]	(73)	8
UL [Member]
Changes in Additional Liabilities for Variable Annuity and Insurance Guarantees
Balance, at the beginning of the period		434	332
Incurred claims		59	99
Paid claims		(22)	(18)
Balance, at the end of the period		$ 471	$ 413

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