Loans And Allowance For Loan Losses (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Loans And Allowance For Loan Losses [Abstract]
Loans pledged at the Federal Home Loan Bank as collateral for borrowings and letters of credit obtained to secure public deposits	$ 3,300,000,000
Loans pledged at the Federal Reserve Bank as collateral for discount window borrowings	1,300,000,000
Personal real estate loans excluded from table	222,300,000	224,500,000
Consumer loans excluded from table	95,300,000	87,400,000
Consumer and personal real estate loans excluded from table, as a percentage of Personal Banking portfolio	7.50%	7.60%
Troubled Debt Restructured Loans	92,800,000
Accruing Restructured Loans	66,359,000	65,508,000
Restructured Loans NonAccrual	26,400,000
Restructured loans performing under their modified terms	42,300,000
Aggregate restructured credit card loans held	13,900,000
Restructured Loans Due to Bankruptcy Proceeding	10,200,000
Period after which loans are deemed in default (in days)	90 days
Effect on Interest Income Resulting From Modification to Credit Card Loans	1,500,000
Commitments to lend additional funds to customers with restructured loans	14,900,000
Foreclosed real estate	14,200,000	13,500,000
Personal property acquired in repossession	$ 2,600,000	$ 3,500,000