Investment Securities (Other Than Temporary Impairment) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net other-than-temporary impairments	$ (4)		$ (34)		$ (14)		$ (72)
Noncredit portion of OTTI (losses) recoveries	(6)	[1]	2	[1]	3	[1]	24	[1]
Other-than-temporary impairments	(10)		(32)		(11)		(48)
Residential Mortgage-backed Securities [Member] | Mortgage-backed Securities Non-agency [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net other-than-temporary impairments	(3)		(31)		(10)		(63)
Asset backed [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net other-than-temporary impairments	(1)		(3)		(4)		(8)
Other Debt Securities [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net other-than-temporary impairments							$ (1)

[1] Included in accumulated other comprehensive income (loss).