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	81,200,000	140,500,000
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	15,460,000	0
Nonaccrual TDRs considered current	55,900,000	50,300,000
Specific reserves related to troubled debt restructuring	12,200,000	8,400,000
Commitments to lend additional funds to borrowers whose terms had been modified in a TDR	1,200,000	434,000
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded investment	44,099,000
Commercial Real Estate [Member] | With No Related Allowance Recorded [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded investment	31,680,000	19,697,000
Commercial Real Estate [Member] | With An Allowance Recorded [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded investment	12,419,000	38,233,000
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
Allowance For Loans And Leases Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Allowance for loans individually evaluated for impairment	33,300,000	43,500,000
With No Related Allowance Recorded [Member]
Financing Receivable, Recorded Investment [Line Items]
Partial charge-offs on impaired loans	52,000,000	12,500,000
With An Allowance Recorded [Member]
Financing Receivable, Recorded Investment [Line Items]
Partial charge-offs on impaired loans	$ 43,900,000	$ 41,100,000