Loans and Allowance for Credit Losses, Loans by FICO Score, Consumer (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2008
Loans by FICO, Excluding Purchased Credit Impaired Loans [Abstract]
Purchased Credit Impaired Loans (carrying value)	$ 27,834	$ 30,968	$ 58,797
Loans	812,325	799,574
Total Consumer [Member]
Loans by FICO, Excluding Purchased Credit Impaired Loans [Abstract]
Purchased Credit Impaired Loans (carrying value)	24,857	26,991	40,093
Loans	440,280	438,376
Real estate 1-4 family first mortgage [Member]
Loans by FICO, Excluding Purchased Credit Impaired Loans [Abstract]
Purchased Credit Impaired Loans (carrying value)	24,730	26,839	39,214
Loans	254,924	249,900
Real estate 1-4 family junior lien mortgage [Member]
Loans by FICO, Excluding Purchased Credit Impaired Loans [Abstract]
Purchased Credit Impaired Loans (carrying value)	127	152	728
Loans	67,675	75,465
Credit Card [Member]
Loans by FICO, Excluding Purchased Credit Impaired Loans [Abstract]
Purchased Credit Impaired Loans (carrying value)	0	0
Loans	25,448	24,640
Automobile [Member]
Loans by FICO, Excluding Purchased Credit Impaired Loans [Abstract]
Purchased Credit Impaired Loans (carrying value)	0	0	151
Loans	49,693	45,998
Other revolving credit and installment [Member]
Loans by FICO, Excluding Purchased Credit Impaired Loans [Abstract]
Purchased Credit Impaired Loans (carrying value)	0	0
Loans	42,540	42,373
Loans Excluding Purchased Credit-Impaired Loans [Member] | Total Consumer [Member]
Loans by FICO, Excluding Purchased Credit Impaired Loans [Abstract]
Less than 600	31,413	35,189
600-639	21,777	22,232
640-679	36,535	36,263
680-719	53,137	52,716
720-759	64,440	63,337
760-799	106,888	102,300
Greater than 800	49,208	43,148
No FICO available	6,537	8,632
FICO not required	4,855	5,403
Government insured/guaranteed loans	40,633	42,165
Loans, excluding Purchased Credit Impaired Loans	415,423	411,385
Loans Excluding Purchased Credit-Impaired Loans [Member] | Real estate 1-4 family first mortgage [Member]
Loans by FICO, Excluding Purchased Credit Impaired Loans [Abstract]
Less than 600	14,914	17,662
600-639	9,397	10,208
640-679	15,407	15,764
680-719	24,809	24,725
720-759	33,414	31,502
760-799	70,177	63,946
Greater than 800	29,576	26,044
No FICO available	2,944	3,491
FICO not required	0	0
Government insured/guaranteed loans	29,556	29,719
Loans, excluding Purchased Credit Impaired Loans	230,194	223,061
Loans Excluding Purchased Credit-Impaired Loans [Member] | Real estate 1-4 family junior lien mortgage [Member]
Loans by FICO, Excluding Purchased Credit Impaired Loans [Abstract]
Less than 600	5,270	6,122
600-639	3,366	3,660
640-679	6,141	6,574
680-719	10,413	11,361
720-759	14,160	15,992
760-799	19,740	21,874
Greater than 800	7,461	8,526
No FICO available	997	1,204
FICO not required	0	0
Government insured/guaranteed loans	0	0
Loans, excluding Purchased Credit Impaired Loans	67,548	75,313
Loans Excluding Purchased Credit-Impaired Loans [Member] | Credit Card [Member]
Loans by FICO, Excluding Purchased Credit Impaired Loans [Abstract]
Less than 600	2,295	2,314
600-639	2,072	1,961
640-679	3,996	3,772
680-719	5,192	4,990
720-759	5,289	5,114
760-799	4,244	4,109
Greater than 800	2,114	2,223
No FICO available	246	157
FICO not required	0	0
Government insured/guaranteed loans	0	0
Loans, excluding Purchased Credit Impaired Loans	25,448	24,640
Loans Excluding Purchased Credit-Impaired Loans [Member] | Automobile [Member]
Loans by FICO, Excluding Purchased Credit Impaired Loans [Abstract]
Less than 600	8,013	7,928
600-639	5,945	5,451
640-679	8,880	8,142
680-719	8,850	7,949
720-759	6,400	5,787
760-799	6,076	5,400
Greater than 800	5,100	4,443
No FICO available	429	898
FICO not required	0	0
Government insured/guaranteed loans	0	0
Loans, excluding Purchased Credit Impaired Loans	49,693	45,998
Loans Excluding Purchased Credit-Impaired Loans [Member] | Other revolving credit and installment [Member]
Loans by FICO, Excluding Purchased Credit Impaired Loans [Abstract]
Less than 600	921	1,163
600-639	997	952
640-679	2,111	2,011
680-719	3,873	3,691
720-759	5,177	4,942
760-799	6,651	6,971
Greater than 800	4,957	1,912
No FICO available	1,921	2,882
FICO not required	4,855	5,403
Government insured/guaranteed loans	11,077	12,446
Loans, excluding Purchased Credit Impaired Loans	$ 42,540	$ 42,373