Loans and Allowance for Credit Losses, Loans Outstanding (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 799,966	$ 799,574
Total Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	361,714	361,198
Commercial and Industrial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	185,623	187,759
Commercial Real Estate Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	106,119	106,340
Commercial Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	16,650	16,904
Lease Financing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	12,402	12,424
Foreign Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	40,920	37,771
Total Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	438,252	438,376
Real estate 1-4 family first mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	252,307	249,900
Real estate 1-4 family junior lien mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	72,543	75,465
Credit Card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	24,120	24,640
Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	47,259	45,998
Other revolving credit and installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 42,023	$ 42,373

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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