Loans and Allowance for Credit Losses, Troubled Debt Restructurings Modifications by Type (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Primary Modification Type [Abstract]
Principal	$ 131	$ 298	$ 519	$ 1,021
Interest rate reduction	248	492	717	1,705
Other concessions, primary modification type	1,187	1,689	3,880	5,680
Total	1,566	2,479	5,116	8,406
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	44	73	180	261
Weighted average interest rate reduction	3.30%	3.30%	3.38%	3.22%
Recorded investment related to interest rate reduction	354	741	1,096	2,431
Total Commercial [Member]
Primary Modification Type [Abstract]
Principal	4	2	11	45
Interest rate reduction	61	142	193	398
Other concessions, primary modification type	387	715	1,633	2,243
Total	452	859	1,837	2,686
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	3	7	29	18
Weighted average interest rate reduction	1.25%	2.60%	1.33%	2.99%
Recorded investment related to interest rate reduction	61	142	193	398
Commercial and Industrial Loans [Member]
Primary Modification Type [Abstract]
Principal	0	2	4	2
Interest rate reduction	9	73	45	156
Other concessions, primary modification type	176	316	687	877
Total	185	391	736	1,035
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	3	6	29	7
Weighted average interest rate reduction	1.29%	3.58%	1.61%	5.09%
Recorded investment related to interest rate reduction	9	73	45	156
Commercial Real Estate Mortgage [Member]
Primary Modification Type [Abstract]
Principal	4	0	7	28
Interest rate reduction	50	62	143	232
Other concessions, primary modification type	180	345	748	1,113
Total	234	407	898	1,373
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	0	1	0	7
Weighted average interest rate reduction	1.20%	1.65%	1.22%	1.67%
Recorded investment related to interest rate reduction	50	62	143	232
Commercial Real Estate Construction [Member]
Primary Modification Type [Abstract]
Principal	0	0	0	0
Interest rate reduction	2	6	4	9
Other concessions, primary modification type	31	54	198	253
Total	33	60	202	262
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	0	0	0	4
Weighted average interest rate reduction	2.15%	1.08%	1.88%	1.02%
Recorded investment related to interest rate reduction	2	6	4	9
Foreign Loans [Member]
Primary Modification Type [Abstract]
Principal	0	0	0	15
Interest rate reduction	0	1	1	1
Other concessions, primary modification type	0	0	0	0
Total	0	1	1	16
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	0	0	0	0
Weighted average interest rate reduction	0.00%	0.26%	0.84%	0.00%
Recorded investment related to interest rate reduction	0	1	1	1
Total Consumer [Member]
Primary Modification Type [Abstract]
Principal	127	296	508	976
Interest rate reduction	187	350	524	1,307
Other concessions, primary modification type	800	974	2,247	3,437
Total	1,114	1,620	3,279	5,720
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	41	66	151	243
Weighted average interest rate reduction	3.73%	3.46%	3.82%	3.27%
Recorded investment related to interest rate reduction	293	599	903	2,033
Real estate 1-4 family first mortgage [Member]
Primary Modification Type [Abstract]
Principal	115	271	464	897
Interest rate reduction	113	259	306	1,016
Other concessions, primary modification type	682	832	2,060	2,928
Total	910	1,362	2,830	4,841
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	15	49	75	194
Weighted average interest rate reduction	2.34%	2.80%	2.53%	2.63%
Recorded investment related to interest rate reduction	209	485	649	1,671
Real estate 1-4 family junior lien mortgage [Member]
Primary Modification Type [Abstract]
Principal	12	24	42	76
Interest rate reduction	31	41	90	135
Other concessions, primary modification type	62	77	199	335
Total	105	142	331	546
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	17	8	50	24
Weighted average interest rate reduction	3.23%	3.43%	3.27%	3.30%
Recorded investment related to interest rate reduction	41	64	126	206
Credit Card [Member]
Primary Modification Type [Abstract]
Principal	0	0	0	0
Interest rate reduction	38	46	118	138
Other concessions, primary modification type	0	0	0	0
Total	38	46	118	138
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	0	0	0	0
Weighted average interest rate reduction	11.59%	10.15%	11.33%	10.47%
Recorded investment related to interest rate reduction	38	46	118	138
Automobile [Member]
Primary Modification Type [Abstract]
Principal	0	1	2	3
Interest rate reduction	2	2	4	10
Other concessions, primary modification type	22	26	65	74
Total	24	29	71	87
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	9	9	26	25
Weighted average interest rate reduction	8.46%	8.98%	8.87%	7.39%
Recorded investment related to interest rate reduction	2	2	4	10
Other revolving credit and installment [Member]
Primary Modification Type [Abstract]
Principal	0	0	0	0
Interest rate reduction	3	2	6	8
Other concessions, primary modification type	6	2	10	9
Total	9	4	16	17
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	0	0	0	0
Weighted average interest rate reduction	5.22%	5.40%	5.05%	4.95%
Recorded investment related to interest rate reduction	3	2	6	8
Trial modifications [Member]
Primary Modification Type [Abstract]
Principal	0	0	0	0
Interest rate reduction	0	0	0	0
Other concessions, primary modification type	28	37	(87)	91
Total	28	37	(87)	91
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	0	0	0	0
Weighted average interest rate reduction	0.00%	0.00%	0.00%	0.00%
Recorded investment related to interest rate reduction	$ 0	$ 0	$ 0	$ 0