Asset Quality (TDRs which have Subsequently Defaulted) (Details) (Subsequently Defaulted TDRs, USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012 contracts	Sep. 30, 2011 contracts	Sep. 30, 2012 contracts	Sep. 30, 2011 contracts
Financing Receivable, Modifications [Line Items]
Number of Contracts	2,392	2,833	4,169	4,865
Recorded Investment	$ 86	$ 147	$ 240	$ 306
Total commercial lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	29	25	115	48
Recorded Investment	37	76	103	150
Total consumer lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	2,363	2,808	4,054	4,817
Recorded Investment	49	71	137	156
Commercial [Member] | Total commercial lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	20	16	78	20
Recorded Investment	19	16	34	39
Commercial Real Estate [Member] | Total commercial lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	9	9	32	28
Recorded Investment	18	60	58	111
Equipment Lease Financing [Member] | Total commercial lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts			5
Recorded Investment			11
Home Equity [Member] | Total consumer lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	140	291	506	848
Recorded Investment	13	23	46	68
Residential Real Estate [Member] | Total consumer lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	148	140	455	255
Recorded Investment	20	32	66	63
Credit Card [Member] | Total consumer lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	2,037	2,363	2,979	3,696
Recorded Investment	15	16	21	24
Other Consumer [Member] | Total consumer lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	38	14	114	18
Recorded Investment	$ 1		$ 4	$ 1