Loans (Narrative) (Details) (USD $)	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment [Line Items]
Partial charge-offs on impaired loans		$ 117,500,000	$ 103,800,000
Allowance for loan losses individually evaluated for impairment	7,579,000	7,579,000	15,935,000
Recorded investment, related to loans	27,000,000	27,000,000	52,700,000
TDRs included in nonaccrual loan totals	86,800,000	86,800,000	100,400,000
TDRs included in accruing loan totals	31,500,000	31,500,000	28,700,000
Nonaccrual TDRs considered current	60,500,000	60,500,000	79,900,000
Commitments to lend additional funds to borrowers whose terms had been modified in a TDR	4,100,000	4,100,000	4,000,000
Specific reserves related to troubled debt restructuring	5,500,000	5,500,000	9,100,000
Additional specific reserves related to troubled debt restructurings	167,000	1,200,000
Modified substandard commercial loans, total recorded investment	2,100,000	2,100,000
Modified substandard consumer loans, total recorded investment	20,500,000	20,500,000
Loan Modifications on Nonacrrual status	1,200,000	7,200,000
Loan modification coverage period		12 days
Loan past due period before entering default status		30 days
Loans modified during period		15,700,000
Recorded investment	17,200,000	17,200,000
Financing Receivable With No Related Allowance Recorded [Member]
Financing Receivable, Recorded Investment [Line Items]
Partial charge-offs on impaired loans		111,500,000	83,700,000
Financing Receivable With A Related Allowance Recorded [Member]
Financing Receivable, Recorded Investment [Line Items]
Partial charge-offs on impaired loans		6,000,000	20,100,000
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Allowance for loan losses individually evaluated for impairment	1,134,000	1,134,000	4,431,000
Accruing [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans modified during period		91,000
Recorded investment	362,000	362,000
Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans modified during period		15,600,000
Recorded investment	$ 16,900,000	$ 16,900,000