Business Segment Information (Market Segment Financial Results) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Net interest income (expense) (FTE)									$ 1,657		$ 1,651		$ 1,575
Provision for loan losses	19	38	47	49	57	122	126	175	153		480		1,082
Noninterest income									792		789		1,050
Noninterest expenses	478	460	409	415	437	402	397	404	1,762		1,640		1,650
Provision (benefit) for income taxes (FTE)									141		60		(123)
Income from discontinued operations, net of tax					0	0	0	17	0		17		1
Net income (loss)	96	98	96	103	96	59	70	52	393		277		17
Net credit-related charge-offs									328		564		869
Assets, average	56,917				55,553				56,917		55,553		62,809
Loans, average									40,075		40,517		46,162
Deposits, average									43,762		39,486		40,091
Return on average assets									0.69%	[1]	0.50%	[1]	0.03%	[1]
Efficiency ratio									72.39%		67.30%		69.25%
Midwest [Member]
Net interest income (expense) (FTE)									808		816		802
Provision for loan losses									91		199		437
Noninterest income									381		397		433
Noninterest expenses									738		751		757
Provision (benefit) for income taxes (FTE)									133		92		0
Income from discontinued operations, net of tax											0		0
Net income (loss)									227		171		41
Net credit-related charge-offs									148		211		345
Assets, average	14,168				14,694				14,168		14,694		17,203
Loans, average									13,937		14,510		16,592
Deposits, average									18,536		17,697		17,105
Return on average assets									1.15%	[1]	0.90%	[1]	0.22%	[1]
Efficiency ratio									61.93%		61.59%		61.24%
Western [Member]
Net interest income (expense) (FTE)									665		639		623
Provision for loan losses									32		148		358
Noninterest income									139		135		133
Noninterest expenses									432		432		434
Provision (benefit) for income taxes (FTE)									125		80		(20)
Income from discontinued operations, net of tax											0		0
Net income (loss)									215		114		(16)
Net credit-related charge-offs									89		212		327
Assets, average	12,323				12,904				12,323		12,904		14,479
Loans, average									12,103		12,705		14,281
Deposits, average									12,839		12,031		11,104
Return on average assets									1.56%	[1]	0.86%	[1]	(0.11%)	[1]
Efficiency ratio									53.65%		55.73%		57.45%
Texas [Member]
Net interest income (expense) (FTE)									477		318		298
Provision for loan losses									3		48		85
Noninterest income									103		91		86
Noninterest expenses									293		253		238
Provision (benefit) for income taxes (FTE)									103		38		22
Income from discontinued operations, net of tax											0		0
Net income (loss)									181		70		39
Net credit-related charge-offs									17		47		53
Assets, average	8,092				6,687				8,092		6,687		7,604
Loans, average									7,705		6,480		7,384
Deposits, average									7,805		5,320		4,512
Return on average assets									2.12%	[1]	1.04%	[1]	0.52%	[1]
Efficiency ratio									50.40%		61.88%		61.92%
Florida [Member]
Net interest income (expense) (FTE)									45		43		43
Provision for loan losses									24		33		59
Noninterest income									14		14		12
Noninterest expenses									49		44		37
Provision (benefit) for income taxes (FTE)									(5)		(7)		(17)
Income from discontinued operations, net of tax											0		0
Net income (loss)									(9)		(13)		(24)
Net credit-related charge-offs									35		30		48
Assets, average	1,492				1,567				1,492		1,567		1,741
Loans, average									1,520		1,578		1,745
Deposits, average									401		376		311
Return on average assets									(0.59%)	[1]	(0.86%)	[1]	(1.34%)	[1]
Efficiency ratio									81.80%		77.99%		66.96%
Other Markets [Member]
Net interest income (expense) (FTE)									169		182		164
Provision for loan losses									9		60		93
Noninterest income									42		45		52
Noninterest expenses									89		90		85
Provision (benefit) for income taxes (FTE)									(11)		(23)		(39)
Income from discontinued operations, net of tax											0		0
Net income (loss)									124		100		77
Net credit-related charge-offs									36		59		78
Assets, average	3,433				3,922				3,433		3,922		4,570
Loans, average									3,146		3,653		4,256
Deposits, average									2,389		2,160		1,598
Return on average assets									3.60%	[1]	2.54%	[1]	1.66%	[1]
Efficiency ratio									44.28%		41.44%		42.40%
International [Member]
Net interest income (expense) (FTE)									77		73		69
Provision for loan losses									(2)		(7)		33
Noninterest income									35		35		34
Noninterest expenses									36		34		31
Provision (benefit) for income taxes (FTE)									28		28		14
Income from discontinued operations, net of tax											0		0
Net income (loss)									50		53		25
Net credit-related charge-offs									3		5		18
Assets, average	1,717				1,627				1,717		1,627		1,954
Loans, average									1,640		1,565		1,909
Deposits, average									1,432		1,153		828
Return on average assets									2.92%	[1]	3.23%	[1]	1.25%	[1]
Efficiency ratio									31.81%		31.55%		30.31%
Finance & Other Businesses [Member]
Net interest income (expense) (FTE)									(584)		(420)		(424)
Provision for loan losses									(4)		(1)		17
Noninterest income									78		72		300
Noninterest expenses									125		36		68
Provision (benefit) for income taxes (FTE)									(232)		(148)		(83)
Income from discontinued operations, net of tax											17		1
Net income (loss)									(395)		(218)		(125)
Net credit-related charge-offs									0		0		0
Assets, average	15,692				14,152				15,692		14,152		15,258
Loans, average									24		26		(5)
Deposits, average									$ 360		$ 749		$ 4,633

[1] Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity.