Allowance for Credit Losses (Schedule of Information Regarding Impaired Loans) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended		12 Months Ended
	Sep. 30, 2012		Dec. 31, 2011
Related allowance	$ 2,051		$ 2,256
Government Guaranteed Loans [Member]
Recorded investment	272		232
Related allowance	21		27
Impaired Loans Excluding Acquired Impaired [Member]
Recorded investment	2,313	[1]	2,577	[1]
Unpaid principal balance	2,764	[1]	3,048	[1]
Related allowance	345	[1]	405	[1]
Average recorded investment	2,395	[1]	2,728	[1]
Interest income recognized	39	[1]	59	[1]
With No Related Allowance Recorded [Member] | Commercial and Industrial [Member]
Recorded investment	127		114
Unpaid principal balance	230		196
Average recorded investment	119		153
Interest income recognized	0		0
With No Related Allowance Recorded [Member] | Commercial Real Estate - Other [Member]
Recorded investment	63		102
Unpaid principal balance	110		163
Average recorded investment	86		142
Interest income recognized	0		0
With No Related Allowance Recorded [Member] | Commercial Real Estate - Residential ADC [Member]
Recorded investment	84		153
Unpaid principal balance	198		289
Average recorded investment	113		187
Interest income recognized	0		0
With No Related Allowance Recorded [Member] | Direct Retail Lending [Member]
Recorded investment	19		19
Unpaid principal balance	73		74
Average recorded investment	19		23
Interest income recognized	1		1
With No Related Allowance Recorded [Member] | Retail Residential Mortgage [Member]
Recorded investment	93	[1]	46	[1]
Unpaid principal balance	158	[1]	85	[1]
Average recorded investment	74	[1]	31	[1]
Interest income recognized	1	[1]	1	[1]
With No Related Allowance Recorded [Member] | Retail Sales Finance [Member]
Recorded investment	1		1
Unpaid principal balance	2		1
Average recorded investment	1		1
Interest income recognized	0		0
With No Related Allowance Recorded [Member] | Retail Other Lending Subsidiaries [Member]
Recorded investment	2		2
Unpaid principal balance	5		4
Average recorded investment	3		1
Interest income recognized	0		0
With An Allowance Recorded [Member] | Commercial and Industrial [Member]
Recorded investment	540		542
Unpaid principal balance	563		552
Related allowance	76		77
Average recorded investment	539		482
Interest income recognized	2		4
With An Allowance Recorded [Member] | Commercial Real Estate - Other [Member]
Recorded investment	303		409
Unpaid principal balance	309		433
Related allowance	42		69
Average recorded investment	322		466
Interest income recognized	4		7
With An Allowance Recorded [Member] | Commercial Real Estate - Residential ADC [Member]
Recorded investment	149		267
Unpaid principal balance	159		298
Related allowance	27		50
Average recorded investment	196		360
Interest income recognized	1		4
With An Allowance Recorded [Member] | Commercial Other Lending Subsidiaries
Recorded investment	4		5
Unpaid principal balance	4		5
Related allowance	1		1
Average recorded investment	6		4
Interest income recognized	0		0
With An Allowance Recorded [Member] | Direct Retail Lending [Member]
Recorded investment	139		146
Unpaid principal balance	147		153
Related allowance	31		35
Average recorded investment	137		148
Interest income recognized	6		9
With An Allowance Recorded [Member] | Retail Revolving Credit [Member]
Recorded investment	58		62
Unpaid principal balance	57		61
Related allowance	25		27
Average recorded investment	60		62
Interest income recognized	2		3
With An Allowance Recorded [Member] | Retail Residential Mortgage [Member]
Recorded investment	639	[1]	653	[1]
Unpaid principal balance	654	[1]	674	[1]
Related allowance	100	[1]	125	[1]
Average recorded investment	648	[1]	627	[1]
Interest income recognized	21	[1]	28	[1]
With An Allowance Recorded [Member] | Retail Sales Finance [Member]
Recorded investment	10		9
Unpaid principal balance	10		10
Related allowance	1		1
Average recorded investment	13		6
Interest income recognized	0		0
With An Allowance Recorded [Member] | Retail Other Lending Subsidiaries [Member]
Recorded investment	82		47
Unpaid principal balance	85		50
Related allowance	42		20
Average recorded investment	59		35
Interest income recognized	$ 1		$ 2

[1] Residential mortgage loans exclude $272 million and $232 million in government guaranteed loans and related allowance of $21 million and $27 million as of September 30, 2012 and December 31, 2011, respectively.