Loans and Allowance for Credit Losses, Loans Outstanding (Details) - USD ($) $ in Millions	Jun. 30, 2015		Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 888,459	[1]	$ 862,551
Total Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	438,022		414,826
Commercial and Industrial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	284,817		271,795
Commercial Real Estate Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	119,695		111,996
Commercial Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	21,309		18,728
Lease Financing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	12,201		12,307
Total Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	450,437		447,725
Real estate 1-4 family first mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	267,868		265,386
Real estate 1-4 family junior lien mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	56,164		59,717
Credit Card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	31,135		31,119
Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	57,801		55,740
Other revolving credit and installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	37,469		35,763
Geographic Distribution, Foreign [Member] | Total Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	54,653		50,037
Geographic Distribution, Foreign [Member] | Commercial and Industrial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	44,838		44,707
Geographic Distribution, Foreign [Member] | Commercial Real Estate Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	9,125		4,776
Geographic Distribution, Foreign [Member] | Commercial Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	389		218
Geographic Distribution, Foreign [Member] | Lease Financing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 301		$ 336

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