Variable Annuity and Insurance Guarantees (Liability Rollforward) (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2017	Jun. 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		1	3
Paid claims		(1)	(6)
Balance, at the end of the period		16	11
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]	(278)	1,099
Balance, at the end of the period	[1]	739	2,156
GMAB [Member]
Changes in Additional Liabilities for Variable Annuity and Insurance Guarantees
Balance, at the beginning of the period	[1]	(24)
Incurred claims	[1]	(33)	45
Paid claims	[1]		(1)
Balance, at the end of the period	[1]	(57)	44
UL [Member]
Changes in Additional Liabilities for Variable Annuity and Insurance Guarantees
Balance, at the beginning of the period		434	332
Incurred claims		52	44
Paid claims		(16)	(12)
Balance, at the end of the period		$ 470	$ 364

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