Loans and Allowance for Credit Losses, PCI, by Delinquency Status, Commercial (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Dec. 31, 2008
Purchased Credit Impaired Loans Commercial Days Past Due [Abstract]
90+ DPD and still accruing	$ 18,295	$ 23,219
Purchased Credit Impaired Loans	24,236	26,727	58,797
Purchased Credit-Impaired Loans [Member]
Purchased Credit Impaired Loans Commercial Days Past Due [Abstract]
90+ DPD and still accruing	4,000	4,500
Total Commercial [Member]
Purchased Credit Impaired Loans Commercial Days Past Due [Abstract]
Purchased Credit Impaired Loans	1,859	2,504	18,704
Total Commercial [Member] | Purchased Credit-Impaired Loans [Member]
Purchased Credit Impaired Loans Commercial Days Past Due [Abstract]
Current-29 DPD and still accruing	1,711	2,249
30-89 DPD and still accruing	6	48
90+ DPD and still accruing	142	207
Purchased Credit Impaired Loans	1,859	2,504
Commercial and Industrial Loans [Member]
Purchased Credit Impaired Loans Commercial Days Past Due [Abstract]
Purchased Credit Impaired Loans	246	215	4,580
Commercial and Industrial Loans [Member] | Purchased Credit-Impaired Loans [Member]
Purchased Credit Impaired Loans Commercial Days Past Due [Abstract]
Current-29 DPD and still accruing	243	210
30-89 DPD and still accruing	1	5
90+ DPD and still accruing	2	0
Purchased Credit Impaired Loans	246	215
Commercial Real Estate Mortgage [Member]
Purchased Credit Impaired Loans Commercial Days Past Due [Abstract]
Purchased Credit Impaired Loans	973	1,136	5,803
Commercial Real Estate Mortgage [Member] | Purchased Credit-Impaired Loans [Member]
Purchased Credit Impaired Loans Commercial Days Past Due [Abstract]
Current-29 DPD and still accruing	914	1,052
30-89 DPD and still accruing	5	41
90+ DPD and still accruing	54	43
Purchased Credit Impaired Loans	973	1,136
Commercial Real Estate Construction [Member]
Purchased Credit Impaired Loans Commercial Days Past Due [Abstract]
Purchased Credit Impaired Loans	237	433	6,462
Commercial Real Estate Construction [Member] | Purchased Credit-Impaired Loans [Member]
Purchased Credit Impaired Loans Commercial Days Past Due [Abstract]
Current-29 DPD and still accruing	195	355
30-89 DPD and still accruing	0	2
90+ DPD and still accruing	42	76
Purchased Credit Impaired Loans	237	433
Foreign Loans [Member]
Purchased Credit Impaired Loans Commercial Days Past Due [Abstract]
Purchased Credit Impaired Loans	403	720	1,859
Foreign Loans [Member] | Purchased Credit-Impaired Loans [Member]
Purchased Credit Impaired Loans Commercial Days Past Due [Abstract]
Current-29 DPD and still accruing	359	632
30-89 DPD and still accruing	0	0
90+ DPD and still accruing	44	88
Purchased Credit Impaired Loans	$ 403	$ 720