Loans and Allowance for Loan and Lease Losses (Details 4) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Impaired loans
Loans without a specific valuation allowance, Recorded Balance
Loans with a specific valuation allowance, Recorded Balance	18,672		18,672		15,982
All Impaired Loans, Recorded Balance	18,672		18,672
Loans without a specific valuation allowance, Unpaid Principal Balance
Loans with a specific valuation allowance, Unpaid Principal Balance	19,215		19,215		16,226
All Impaired Loans, Unpaid Principal Balance	19,215		19,215
Specific allowance	1,690		1,690		1,737
All Impaired Loans, Specific Allowance	1,690		1,690
Loans without a specific valuation allowance, Average Investment In Impaired Loans
Loans with a specific valuation allowance, Average Investment In Impaired Loans	18,718	15,063	17,226	16,635	16,424
All Impaired Loans, Average Investment in Impaired Loans	18,718		17,226
Loans without a specific valuation allowance, Interest Income Recognized
Loans with a specific valuation allowance, Interest Income Recognized	106	140	231	425	354
All Impaired Loans, Interest Income Recognized	106		231
Commercial Real estate loans [Member]
Impaired loans
Loans without a specific valuation allowance, Recorded Balance
Loans with a specific valuation allowance, Recorded Balance	5,819		5,819		4,891
Loans without a specific valuation allowance, Unpaid Principal Balance
Loans with a specific valuation allowance, Unpaid Principal Balance	5,819		5,819		4,891
Specific allowance	426		426		445
Loans without a specific valuation allowance, Average Investment In Impaired Loans
Loans with a specific valuation allowance, Average Investment In Impaired Loans	5,864	4,800	5,497	5,462	5,318
Loans without a specific valuation allowance, Interest Income Recognized
Loans with a specific valuation allowance, Interest Income Recognized	51	93	121	280	181
Residential Real estate loans [Member]
Impaired loans
Loans without a specific valuation allowance, Recorded Balance
Loans with a specific valuation allowance, Recorded Balance	6,675		6,675		6,440
Loans without a specific valuation allowance, Unpaid Principal Balance
Loans with a specific valuation allowance, Unpaid Principal Balance	6,932		6,932		6,494
Specific allowance	462		462		707
Loans without a specific valuation allowance, Average Investment In Impaired Loans
Loans with a specific valuation allowance, Average Investment In Impaired Loans	6,627	5,922	6,340	6,099	6,142
Loans without a specific valuation allowance, Interest Income Recognized
Loans with a specific valuation allowance, Interest Income Recognized	19	20	59	80	100
Construction Real estate loans [Member]
Impaired loans
Loans without a specific valuation allowance, Recorded Balance
Loans with a specific valuation allowance, Recorded Balance	4,887		4,887		3,672
Loans without a specific valuation allowance, Unpaid Principal Balance
Loans with a specific valuation allowance, Unpaid Principal Balance	5,142		5,142		3,842
Specific allowance	334		334		435
Loans without a specific valuation allowance, Average Investment In Impaired Loans
Loans with a specific valuation allowance, Average Investment In Impaired Loans	4,838	3,320	4,220	4,057	3,962
Loans without a specific valuation allowance, Interest Income Recognized
Loans with a specific valuation allowance, Interest Income Recognized	33	25	40	54	57
Commercial loans and leases [Member]
Impaired loans
Loans without a specific valuation allowance, Recorded Balance
Loans with a specific valuation allowance, Recorded Balance	1,242		1,242		935
Loans without a specific valuation allowance, Unpaid Principal Balance
Loans with a specific valuation allowance, Unpaid Principal Balance	1,273		1,273		955
Specific allowance	453		453		142
Loans without a specific valuation allowance, Average Investment In Impaired Loans
Loans with a specific valuation allowance, Average Investment In Impaired Loans	1,335	973	1,121	965	952
Loans without a specific valuation allowance, Interest Income Recognized
Loans with a specific valuation allowance, Interest Income Recognized	3	2	11	11	16
Municipal loans [Member]
Impaired loans
Loans without a specific valuation allowance, Recorded Balance
Loans with a specific valuation allowance, Recorded Balance	0		0
Loans without a specific valuation allowance, Unpaid Principal Balance
Loans with a specific valuation allowance, Unpaid Principal Balance	0		0
Specific allowance	0		0
Loans without a specific valuation allowance, Average Investment In Impaired Loans
Loans with a specific valuation allowance, Average Investment In Impaired Loans	0		0
Loans without a specific valuation allowance, Interest Income Recognized
Loans with a specific valuation allowance, Interest Income Recognized	0		0
Consumer loans [Member]
Impaired loans
Loans without a specific valuation allowance, Recorded Balance
Loans with a specific valuation allowance, Recorded Balance	49		49		44
Loans without a specific valuation allowance, Unpaid Principal Balance
Loans with a specific valuation allowance, Unpaid Principal Balance	49		49		44
Specific allowance	15		15		8
Loans without a specific valuation allowance, Average Investment In Impaired Loans
Loans with a specific valuation allowance, Average Investment In Impaired Loans	54	48	48	52	50
Loans without a specific valuation allowance, Interest Income Recognized
Loans with a specific valuation allowance, Interest Income Recognized	$ 0		$ 0