Loans and Commitments to Extend Credit (Loans Outstanding) (Details) (USD $)	Jun. 30, 2013		Dec. 31, 2012		Jun. 30, 2012
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 189,775,000,000	[1],[2]	$ 185,856,000,000	[1],[2]	$ 180,425,000,000
Unearned income, net deferred loan fees, unamortized discounts and premiums, and purchase discounts and premiums	2,300,000,000		2,700,000,000
Commercial Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	113,270,000,000		108,942,000,000
Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	76,505,000,000		76,914,000,000
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	86,930,000,000		83,040,000,000
Commercial [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	86,930,000,000		83,040,000,000
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	18,991,000,000		18,655,000,000
Commercial Real Estate [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	18,991,000,000		18,655,000,000
Equipment Lease Financing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	7,349,000,000		7,247,000,000
Equipment Lease Financing [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	7,349,000,000		7,247,000,000
Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	36,416,000,000		35,920,000,000
Home Equity [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	36,416,000,000		35,920,000,000
Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	14,777,000,000		15,240,000,000
Residential Real Estate [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	14,777,000,000		15,240,000,000
Credit Card [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	4,135,000,000		4,303,000,000
Credit Card [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	4,135,000,000		4,303,000,000
Other Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	21,177,000,000		21,451,000,000
Other Consumer Loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 21,177,000,000		$ 21,451,000,000

[1] Amounts represent the assets or liabilities of consolidated variable interest entities (VIEs).

[2] Amounts represent items for which the Corporation has elected the fair value option.