Loans (Narrative) (Details) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2011	Dec. 31, 2010
Financing Receivable, Recorded Investment [Line Items]
Partial charge-offs on impaired loans	$ 95,900,000	$ 53,600,000
Recorded investment, related to loans	86,300,000	162,300,000
Recorded investment	192,464,000	250,933,000
TDRs included in nonaccrual loan totals	82,100,000	80,700,000
TDRs included in accruing loan totals	15,600,000	0
Nonaccrual TDRs considered current	55,900,000	50,300,000
Specific reserves related to troubled debt restructuring	12,200,000	9,400,000
Commitments to lend additional funds to borrowers whose terms had been modified in a TDR	1,200,000	434,000
With No Related Allowance Recorded [Member]
Financing Receivable, Recorded Investment [Line Items]
Partial charge-offs on impaired loans	42,300,000	12,000,000
With An Allowance Recorded [Member]
Financing Receivable, Recorded Investment [Line Items]
Partial charge-offs on impaired loans	53,600,000	41,600,000
Allowance For Loans And Leases Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Allowance for loans individually evaluated for impairment	40,300,000	66,900,000
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded investment	21,000
Modified substandard commercial loans, total recorded investment	11,700,000
Consumer [Member] | With No Related Allowance Recorded [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded investment
Consumer [Member] | With An Allowance Recorded [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded investment	21,000
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Modified substandard commercial loans, total recorded investment	$ 6,000,000