Accumulated Other Comprehensive Income (Components of Other Comprehensive (Loss) Income) (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
Change in net unrealized gain on Securities available for sale:
Net unrealized (loss) gain	$ (477)	$ 119	$ (480)	$ 208
Reclassification of impairment charges included in net impairment losses on securities	3	7	7	25
Other reclassifications included in other revenue	(3)	(1)	(3)	(1)
Change in net unrealized gain on securities available for sale	(477)	125	(476)	232
Other			1
Other comprehensive (loss) income, before tax	(477)	125	(475)	232
Change in net unrealized gain on Securities available for sale:
Net unrealized (loss) gain	179	(45)	181	(77)
Reclassification of impairment charges included in net impairment losses on securities		(2)	(2)	(9)
Other reclassifications included in other revenue	1		1
Change in net unrealized gain on securities available for sale	180	(47)	180	(86)
Other comprehensive (loss) income, tax effect	180	(47)	180	(86)
Change in net unrealized gain on securities available for sale:
Net unrealized (loss) gain	(298)	74	(299)	131
Reclassification of impairment charges included in net impairment losses on securities	3	5	5	16
Other reclassifications included in other revenue	(2)	(1)	(2)	(1)
Change in net unrealized gain on securities available for sale	(297)	78	(296)	146
Other			1
Other comprehensive (loss) income, net of tax	$ (297)	$ 78	$ (295)	$ 146