Loans and ACL (Schedule of Information Regarding Impaired Loans) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended		12 Months Ended
	Jun. 30, 2013		Dec. 31, 2012
Related allowance	$ 1,901		$ 2,018
Impaired Loans Excluding Acquired Impaired And Government Guaranteed Loans [Member]
Recorded investment	2,294	[1]	2,434	[1]
Unpaid principal balance	2,694	[1]	2,882	[1]
Related allowance	370	[1]	385	[1]
Average recorded investment	2,397	[1]	2,356	[1]
Interest income recognized	36	[1]	53	[1]
Impaired Financing Receivable With Related Allowance Recorded [Member] | Commercial and Industrial [Member]
Recorded investment	429		515
Unpaid principal balance	462		551
Related allowance	70		73
Average recorded investment	498		522
Interest income recognized	2		3
Impaired Financing Receivable With Related Allowance Recorded [Member] | Commercial Real Estate - Other [Member]
Recorded investment	235		252
Unpaid principal balance	250		255
Related allowance	33		36
Average recorded investment	241		319
Interest income recognized	2		5
Impaired Financing Receivable With Related Allowance Recorded [Member] | Commercial Real Estate - Residential ADC [Member]
Recorded investment	65		111
Unpaid principal balance	69		116
Related allowance	10		21
Average recorded investment	88		180
Interest income recognized	1		1
Impaired Financing Receivable With Related Allowance Recorded [Member] | Commercial Other Lending Subsidiaries [Member]
Recorded investment	3		3
Unpaid principal balance	2		3
Related allowance	0		1
Average recorded investment	2		4
Interest income recognized	0		0
Impaired Financing Receivable With Related Allowance Recorded [Member] | Direct Retail Lending [Member]
Recorded investment	201		216
Unpaid principal balance	205		226
Related allowance	41		59
Average recorded investment	209		140
Interest income recognized	6		9
Impaired Financing Receivable With Related Allowance Recorded [Member] | Retail Revolving Credit [Member]
Recorded investment	53		56
Unpaid principal balance	53		56
Related allowance	23		24
Average recorded investment	55		59
Interest income recognized	1		2
Impaired Financing Receivable With Related Allowance Recorded [Member] | Retail Residential Mortgage [Member]
Recorded investment	743	[1]	754	[1]
Unpaid principal balance	759	[1]	770	[1]
Related allowance	108	[1]	104	[1]
Average recorded investment	746	[1]	649	[1]
Interest income recognized	16	[1]	28	[1]
Impaired Financing Receivable With Related Allowance Recorded [Member] | Retail Sales Finance [Member]
Recorded investment	20		21
Unpaid principal balance	20		21
Related allowance	4		6
Average recorded investment	21		13
Interest income recognized	1		0
Impaired Financing Receivable With Related Allowance Recorded [Member] | Retail Other Lending Subsidiaries [Member]
Recorded investment	200		144
Unpaid principal balance	201		146
Related allowance	81		61
Average recorded investment	171		66
Interest income recognized	4		2
Impaired Financing Receivable With No Related Allowance Recorded [Member] | Commercial and Industrial [Member]
Recorded investment	116		116
Unpaid principal balance	228		232
Average recorded investment	121		117
Interest income recognized	0		0
Impaired Financing Receivable With No Related Allowance Recorded [Member] | Commercial Real Estate - Other [Member]
Recorded investment	43		60
Unpaid principal balance	74		108
Average recorded investment	57		81
Interest income recognized	0		0
Impaired Financing Receivable With No Related Allowance Recorded [Member] | Commercial Real Estate - Residential ADC [Member]
Recorded investment	29		44
Unpaid principal balance	63		115
Average recorded investment	39		103
Interest income recognized	0		0
Impaired Financing Receivable With No Related Allowance Recorded [Member] | Commercial Other Lending Subsidiaries [Member]
Recorded investment	0
Unpaid principal balance	0
Average recorded investment	0
Interest income recognized	0
Impaired Financing Receivable With No Related Allowance Recorded [Member] | Direct Retail Lending [Member]
Recorded investment	24		19
Unpaid principal balance	81		73
Average recorded investment	23		19
Interest income recognized	1		1
Impaired Financing Receivable With No Related Allowance Recorded [Member] | Retail Residential Mortgage [Member]
Recorded investment	130	[1]	120	[1]
Unpaid principal balance	217	[1]	201	[1]
Average recorded investment	122	[1]	80	[1]
Interest income recognized	2	[1]	2	[1]
Impaired Financing Receivable With No Related Allowance Recorded [Member] | Retail Sales Finance [Member]
Recorded investment	1		1
Unpaid principal balance	3		3
Average recorded investment	1		1
Interest income recognized	0		0
Impaired Financing Receivable With No Related Allowance Recorded [Member] | Retail Other Lending Subsidiaries [Member]
Recorded investment	2		2
Unpaid principal balance	7		6
Average recorded investment	3		3
Interest income recognized	0		0
Government Guaranteed Loans [Member] | Retail Residential Mortgage [Member]
Recorded investment	366		313
Related allowance	$ 56		$ 26

[1] Residential mortgage loans exclude $366 million and $313 million in government guaranteed loans and related allowance of $56 million and $26 million as of June 30, 2013 and December 31, 2012, respectively.