Loans (Details 4) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Nonaccrual loans and loans past due over 90 days still accruing interest by class of loans
Nonaccrual	$ 18,557	$ 16,567
Past Due Over 90 Days Still on Accrual	454	441
Commercial, industrial, and agricultural [Member]
Nonaccrual loans and loans past due over 90 days still accruing interest by class of loans
Nonaccrual	6,669	6,949
Past Due Over 90 Days Still on Accrual	47	10
Commercial mortgages [Member]
Nonaccrual loans and loans past due over 90 days still accruing interest by class of loans
Nonaccrual	9,353	8,359
Past Due Over 90 Days Still on Accrual	0	122
Residential real estate [Member]
Nonaccrual loans and loans past due over 90 days still accruing interest by class of loans
Nonaccrual	2,532	1,254
Past Due Over 90 Days Still on Accrual	136	157
Consumer [Member]
Nonaccrual loans and loans past due over 90 days still accruing interest by class of loans
Nonaccrual	3	5
Past Due Over 90 Days Still on Accrual	250	125
Credit cards [Member]
Nonaccrual loans and loans past due over 90 days still accruing interest by class of loans
Nonaccrual	0	0
Past Due Over 90 Days Still on Accrual	$ 21	$ 27