Loans and Allowance for Credit Losses, Loans by Credit Quality Indicator, Commercial (Details) - USD ($) $ in Millions	Jun. 30, 2015		Dec. 31, 2014	Dec. 31, 2008
Loans and Leases Receivable Disclosure [Abstract]
Purchased Credit Impaired Loans	$ 21,555		$ 23,320
Loans	888,459	[1]	862,551
Total Commercial [Member]
Loans and Leases Receivable Disclosure [Abstract]
Purchased Credit Impaired Loans	873		1,507	$ 18,700
Loans	438,022		414,826
Commercial and Industrial Loans [Member]
Loans and Leases Receivable Disclosure [Abstract]
Purchased Credit Impaired Loans	86		75
Loans	284,817		271,795
Commercial Real Estate Mortgage [Member]
Loans and Leases Receivable Disclosure [Abstract]
Purchased Credit Impaired Loans	681		1,261
Loans	119,695		111,996
Commercial Real Estate Construction [Member]
Loans and Leases Receivable Disclosure [Abstract]
Purchased Credit Impaired Loans	106		171
Loans	21,309		18,728
Lease Financing [Member]
Loans and Leases Receivable Disclosure [Abstract]
Purchased Credit Impaired Loans	0		0
Loans	12,201		12,307
Loans Excluding Purchased Credit-Impaired Loans [Member] | Total Commercial [Member]
Loans and Leases Receivable Disclosure [Abstract]
Loans, excluding Purchased Credit Impaired Loans	437,149		413,319
Loans Excluding Purchased Credit-Impaired Loans [Member] | Total Commercial [Member] | Pass [Member]
Loans and Leases Receivable Disclosure [Abstract]
Loans, excluding Purchased Credit Impaired Loans	412,044		388,314
Loans Excluding Purchased Credit-Impaired Loans [Member] | Total Commercial [Member] | Criticized [Member]
Loans and Leases Receivable Disclosure [Abstract]
Loans, excluding Purchased Credit Impaired Loans	25,105		25,005
Loans Excluding Purchased Credit-Impaired Loans [Member] | Commercial and Industrial Loans [Member]
Loans and Leases Receivable Disclosure [Abstract]
Loans, excluding Purchased Credit Impaired Loans	284,731		271,720
Loans Excluding Purchased Credit-Impaired Loans [Member] | Commercial and Industrial Loans [Member] | Pass [Member]
Loans and Leases Receivable Disclosure [Abstract]
Loans, excluding Purchased Credit Impaired Loans	268,741		255,611
Loans Excluding Purchased Credit-Impaired Loans [Member] | Commercial and Industrial Loans [Member] | Criticized [Member]
Loans and Leases Receivable Disclosure [Abstract]
Loans, excluding Purchased Credit Impaired Loans	15,990		16,109
Loans Excluding Purchased Credit-Impaired Loans [Member] | Commercial Real Estate Mortgage [Member]
Loans and Leases Receivable Disclosure [Abstract]
Loans, excluding Purchased Credit Impaired Loans	119,014		110,735
Loans Excluding Purchased Credit-Impaired Loans [Member] | Commercial Real Estate Mortgage [Member] | Pass [Member]
Loans and Leases Receivable Disclosure [Abstract]
Loans, excluding Purchased Credit Impaired Loans	111,151		103,319
Loans Excluding Purchased Credit-Impaired Loans [Member] | Commercial Real Estate Mortgage [Member] | Criticized [Member]
Loans and Leases Receivable Disclosure [Abstract]
Loans, excluding Purchased Credit Impaired Loans	7,863		7,416
Loans Excluding Purchased Credit-Impaired Loans [Member] | Commercial Real Estate Construction [Member]
Loans and Leases Receivable Disclosure [Abstract]
Loans, excluding Purchased Credit Impaired Loans	21,203		18,557
Loans Excluding Purchased Credit-Impaired Loans [Member] | Commercial Real Estate Construction [Member] | Pass [Member]
Loans and Leases Receivable Disclosure [Abstract]
Loans, excluding Purchased Credit Impaired Loans	20,392		17,661
Loans Excluding Purchased Credit-Impaired Loans [Member] | Commercial Real Estate Construction [Member] | Criticized [Member]
Loans and Leases Receivable Disclosure [Abstract]
Loans, excluding Purchased Credit Impaired Loans	811		896
Loans Excluding Purchased Credit-Impaired Loans [Member] | Lease Financing [Member]
Loans and Leases Receivable Disclosure [Abstract]
Loans, excluding Purchased Credit Impaired Loans	12,201		12,307
Loans Excluding Purchased Credit-Impaired Loans [Member] | Lease Financing [Member] | Pass [Member]
Loans and Leases Receivable Disclosure [Abstract]
Loans, excluding Purchased Credit Impaired Loans	11,760		11,723
Loans Excluding Purchased Credit-Impaired Loans [Member] | Lease Financing [Member] | Criticized [Member]
Loans and Leases Receivable Disclosure [Abstract]
Loans, excluding Purchased Credit Impaired Loans	$ 441		$ 584

[1] Parenthetical amounts represent assets and liabilities for which we have elected the fair value option.