Allowance for Credit Losses (Schedule of Information Regarding Impaired Loans) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2012		Dec. 31, 2011
Related Allowance	$ 2,181		$ 2,256
Government Guaranteed Loans [Member]
Recorded Investment	237		232
Related Allowance	11		27
Impaired Loans Excluding Acquired Impaired And Government Guaranteed Loans [Member]
Recorded Investment	2,558	[1]	2,577	[1]
Unpaid Principal Balance	2,990	[1]	3,048	[1]
Related Allowance	361	[1]	405	[1]
Average Recorded Investment	2,250	[1]	1,958	[1]
Interest Income Recognized	12	[1]	50	[1]
With No Related Allowance Recorded [Member] | Commercial and Industrial [Member]
Recorded Investment	128		114
Unpaid Principal Balance	223		196
Average Recorded Investment	126		102
Interest Income Recognized	0		0
With No Related Allowance Recorded [Member] | Commercial Real Estate - Other [Member]
Recorded Investment	104		102
Unpaid Principal Balance	159		163
Average Recorded Investment	101		94
Interest Income Recognized	0		1
With No Related Allowance Recorded [Member] | Commercial Real Estate - Residential ADC [Member]
Recorded Investment	108		153
Unpaid Principal Balance	213		289
Average Recorded Investment	110		145
Interest Income Recognized	0		0
With No Related Allowance Recorded [Member] | Direct Retail Lending [Member]
Recorded Investment	21		19
Unpaid Principal Balance	78		74
Average Recorded Investment	22		23
Interest Income Recognized	0		1
With No Related Allowance Recorded [Member] | Retail Residential Mortgage [Member]
Recorded Investment	84	[1]	46	[1]
Unpaid Principal Balance	141	[1]	85	[1]
Average Recorded Investment	82	[1]	55	[1]
Interest Income Recognized	0	[1]	2	[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	4		3
Interest Income Recognized	0		0
With An Allowance Recorded [Member] | Commercial and Industrial [Member]
Recorded Investment	641		542
Unpaid Principal Balance	650		552
Related Allowance	91		77
Average Recorded Investment	470		300
Interest Income Recognized	1		1
With An Allowance Recorded [Member] | Commercial Real Estate - Other [Member]
Recorded Investment	314		409
Unpaid Principal Balance	329		433
Related Allowance	54		69
Average Recorded Investment	272		278
Interest Income Recognized	1		5
With An Allowance Recorded [Member] | Commercial Real Estate - Residential ADC [Member]
Recorded Investment	237		267
Unpaid Principal Balance	247		298
Related Allowance	42		50
Average Recorded Investment	198		164
Interest Income Recognized	0		1
With An Allowance Recorded [Member] | Commercial Other Lending Subsidiaries
Recorded Investment	11		5
Unpaid Principal Balance	13		5
Related Allowance	3		1
Average Recorded Investment	13		5
Interest Income Recognized	0		0
With An Allowance Recorded [Member] | Direct Retail Lending [Member]
Recorded Investment	139		146
Unpaid Principal Balance	146		153
Related Allowance	31		35
Average Recorded Investment	137		128
Interest Income Recognized	2		8
With An Allowance Recorded [Member] | Retail Revolving Credit [Member]
Recorded Investment	61		62
Unpaid Principal Balance	60		61
Related Allowance	26		27
Average Recorded Investment	61		61
Interest Income Recognized	1		3
With An Allowance Recorded [Member] | Retail Residential Mortgage [Member]
Recorded Investment	637	[1]	653	[1]
Unpaid Principal Balance	652	[1]	674	[1]
Related Allowance	91	[1]	125	[1]
Average Recorded Investment	596	[1]	562	[1]
Interest Income Recognized	7	[1]	26	[1]
With An Allowance Recorded [Member] | Retail Sales Finance [Member]
Recorded Investment	17		9
Unpaid Principal Balance	17		10
Related Allowance	1		1
Average Recorded Investment	9		6
Interest Income Recognized	0		0
With An Allowance Recorded [Member] | Retail Other Lending Subsidiaries [Member]
Recorded Investment	53		47
Unpaid Principal Balance	55		50
Related Allowance	22		20
Average Recorded Investment	48		31
Interest Income Recognized	$ 0		$ 2

[1] Residential mortgage loans exclude $237 million and $232 million in government guaranteed loans and related allowance of $11 million and $27 million as of March 31, 2012 and December 31, 2011, respectively.