Loans and Allowance for Credit Losses, Loans Outstanding (Details) - USD ($) $ in Millions	Sep. 30, 2015		Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Deferred Income	$ 3,800		$ 4,500
Loans	903,233	[1]	862,551
Total Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	447,338		414,826
Commercial and Industrial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	292,234		271,795
Commercial Real Estate Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	121,252		111,996
Commercial Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	21,710		18,728
Lease Financing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	12,142		12,307
Total Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	455,895		447,725
Real estate 1-4 family first mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	271,311		265,386
Real estate 1-4 family junior lien mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	54,592		59,717
Credit Card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	32,286		31,119
Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	59,164		55,740
Other revolving credit and installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	38,542		35,763
Geographic Distribution, Foreign [Member] | Total Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	55,717		50,037
Geographic Distribution, Foreign [Member] | Commercial and Industrial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	46,380		44,707
Geographic Distribution, Foreign [Member] | Commercial Real Estate Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	8,662		4,776
Geographic Distribution, Foreign [Member] | Commercial Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	396		218
Geographic Distribution, Foreign [Member] | Lease Financing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 279		$ 336

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