Allowance for Credit Losses (Summary of the primary reason loan modifications were classified as restructurings) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Rate	$ 8	[1],[2]	$ 5	[1],[2]	$ 22	[1],[2]	$ 26	[1],[2]
Structure	12	[1]	9	[1]	51	[1]	36	[1]
Increase to allowance	0		1		0		3
Commercial Real Estate - Other [Member]
Financing Receivable, Modifications [Line Items]
Rate	5	[1],[2]	9	[1],[2]	35	[1],[2]	35	[1],[2]
Structure	26	[1]	22	[1]	40	[1]	45	[1]
Increase to allowance	0		2		0		5
Commercial Real Estate - Residential ADC [Member]
Financing Receivable, Modifications [Line Items]
Rate	3	[1],[2]	7	[1],[2]	25	[1],[2]	23	[1],[2]
Structure	3	[1]	14	[1]	24	[1]	37	[1]
Increase to allowance	0		1		(2)		8
Commercial Other Lending Subsidiaries [Member]
Financing Receivable, Modifications [Line Items]
Rate			1	[1],[2]			1	[1],[2]
Structure			1	[1]			1	[1]
Direct Retail Lending [Member]
Financing Receivable, Modifications [Line Items]
Rate	15	[1],[2]	10	[1],[2]	31	[1],[2]	42	[1],[2]
Structure	6	[1]	1	[1]	12	[1]	4	[1]
Increase to allowance	3		2		6		7
Retail Revolving Credit [Member]
Financing Receivable, Modifications [Line Items]
Rate	8	[1],[2]	10	[1],[2]	23	[1],[2]	31	[1],[2]
Structure	0	[1]	0	[1]	0	[1]	0	[1]
Increase to allowance	1		2		4		6
Retail Residential Mortgage [Member]
Financing Receivable, Modifications [Line Items]
Rate	10	[1],[2]	23	[1],[2]	92	[1],[2]	77	[1],[2]
Structure	18	[1]	2	[1]	64	[1]	7	[1]
Increase to allowance	2		2		11		10
Retail Sales Finance [Member]
Financing Receivable, Modifications [Line Items]
Rate	1	[1],[2]	2	[1],[2]	4	[1],[2]	4	[1],[2]
Structure	0	[1]	0	[1]	0	[1]	3	[1]
Increase to allowance	0		0		0		1
Retail Other Lending Subsidiaries [Member]
Financing Receivable, Modifications [Line Items]
Rate	19	[1],[2]	8	[1],[2]	48	[1],[2]	30	[1],[2]
Structure	0	[1]	2	[1]	2	[1]	5	[1]
Increase to allowance	$ 9		$ 4		$ 17		$ 12

[1] Includes modifications made to existing restructurings, as well as new modifications that are considered restructurings. Balances represent the recorded investment as of the end of the period in which the modification was made.

[2] Includes restructurings made with a below market interest rate that also includes a modification of loan structure.