Loans (Narrative) (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Partial Charge-Offs On Impaired Loans	$ 102,900,000		$ 105,100,000
Allowance for loan losses individually evaluated for impairment	8,260,000		8,276,000
Recorded investment, related to loans	27,100,000		28,800,000
TDRs included in nonaccrual loan totals	84,300,000		84,700,000
TDRs included in accruing loan totals	24,400,000		29,900,000
Nonaccrual TDRs considered current	54,800,000		52,600,000
Commitments to lend additional funds to borrowers whose terms had been modified in a TDR	4,400,000		5,000,000
Specific reserves related to troubled debt restructuring	5,600,000
Additional specific reserves related to troubled debt restructurings	238,000	300,000
Modified substandard commercial loans, total recorded investment	800,000
Modified substandard consumer loans, total recorded investment	6,600,000
Loan Modifications on Nonacrrual status	300,000	6,200,000
Loan past due period before entering default status	30 days
Loans modified during period	7,100,000	21,200,000
Financing Receivable With No Related Allowance Recorded [Member]
Financing Receivable, Recorded Investment [Line Items]
Partial Charge-Offs On Impaired Loans	96,900,000		96,900,000
Financing Receivable With A Related Allowance Recorded [Member]
Financing Receivable, Recorded Investment [Line Items]
Partial Charge-Offs On Impaired Loans	6,000,000		8,200,000
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Allowance for loan losses individually evaluated for impairment	648,000		1,540,000
Accruing [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans modified during period	768,000	205,000
Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans modified during period	$ 6,300,000	$ 21,000,000