Loans and Allowance for Credit Losses, PCI, by Delinquency Status, Commercial (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014	Dec. 31, 2008
By delinquency status:
90+ DPD and still accruing	$ 15,161	$ 17,810
Purchased Credit Impaired Loans	21,555	23,320
Purchased Credit-Impaired Loans [Member]
By delinquency status:
90+ DPD and still accruing	3,400	3,700
Total Commercial [Member]
By delinquency status:
Purchased Credit Impaired Loans	873	1,507	$ 18,700
Total Commercial [Member] | Purchased Credit-Impaired Loans [Member]
By delinquency status:
Current-29 DPD and still accruing	799	1,371
30-89 DPD and still accruing	10	53
90+ DPD and still accruing	64	83
Purchased Credit Impaired Loans	873	1,507
Commercial and Industrial Loans [Member]
By delinquency status:
Purchased Credit Impaired Loans	86	75
Commercial and Industrial Loans [Member] | Purchased Credit-Impaired Loans [Member]
By delinquency status:
Current-29 DPD and still accruing	85	75
30-89 DPD and still accruing	0	0
90+ DPD and still accruing	1	0
Purchased Credit Impaired Loans	86	75
Commercial Real Estate Mortgage [Member]
By delinquency status:
Purchased Credit Impaired Loans	681	1,261
Commercial Real Estate Mortgage [Member] | Purchased Credit-Impaired Loans [Member]
By delinquency status:
Current-29 DPD and still accruing	609	1,135
30-89 DPD and still accruing	10	48
90+ DPD and still accruing	62	78
Purchased Credit Impaired Loans	681	1,261
Commercial Real Estate Construction [Member]
By delinquency status:
Purchased Credit Impaired Loans	106	171
Commercial Real Estate Construction [Member] | Purchased Credit-Impaired Loans [Member]
By delinquency status:
Current-29 DPD and still accruing	105	161
30-89 DPD and still accruing	0	5
90+ DPD and still accruing	1	5
Purchased Credit Impaired Loans	$ 106	$ 171