Loans, Allowance for Loan and Lease Losses, and Reserve for Off-Balance Sheet Credit Commitments (Details 5) (USD $)	12 Months Ended
	Dec. 31, 2012 contract	Dec. 31, 2011 contract
Financing Receivable, Impaired
Troubled debt restructured loans on accrual	$ 48,800,000	$ 46,600,000
TDR loans	94,900,000	89,400,000
Specific Reserves	1,700,000	1,700,000
Total Troubled Debt Restructured Loans
Financing Receivable, Impaired
Number of Contracts	31	39
Pre-Modification Outstanding Principal	79,970,000	82,914,000
Period-End Outstanding Principal	49,723,000	81,799,000
Financial Effects	11,277,000	3,303,000
Commercial
Financing Receivable, Impaired
Number of Contracts	20	12
Pre-Modification Outstanding Principal	38,371,000	12,305,000
Period-End Outstanding Principal	19,671,000	12,111,000
Financial Effects	10,528,000	1,490,000
Commercial real estate mortgages
Financing Receivable, Impaired
Number of Contracts	2	5
Pre-Modification Outstanding Principal	15,833,000	12,908,000
Period-End Outstanding Principal	16,287,000	12,899,000
Fixed
Financing Receivable, Impaired
Number of Contracts	4
Pre-Modification Outstanding Principal	2,233,000
Period-End Outstanding Principal	1,068,000
Financial Effects	485,000
Variable
Financing Receivable, Impaired
Number of Contracts		1
Pre-Modification Outstanding Principal		969,000
Period-End Outstanding Principal		933,000
Real estate construction
Financing Receivable, Impaired
Number of Contracts	4	12
Pre-Modification Outstanding Principal	23,277,000	55,967,000
Period-End Outstanding Principal	12,551,000	55,856,000
Financial Effects	264,000	1,813,000
Construction
Financing Receivable, Impaired
Number of Contracts	3	6
Pre-Modification Outstanding Principal	14,857,000	26,814,000
Period-End Outstanding Principal	4,633,000	26,814,000
Land
Financing Receivable, Impaired
Number of Contracts	1	6
Pre-Modification Outstanding Principal	8,420,000	29,153,000
Period-End Outstanding Principal	7,918,000	29,042,000
Financial Effects	264,000	1,813,000
Equity lines of credit
Financing Receivable, Impaired
Number of Contracts	1
Pre-Modification Outstanding Principal	256,000
Period-End Outstanding Principal	146,000
Lease financing
Financing Receivable, Impaired
Number of Contracts		9
Pre-Modification Outstanding Principal		$ 765,000