Allowance for Loan Losses (Analysis of allowance for loan losses - Additional information) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010
Allowance for loan losses, Additional information
Period-end amount allocated to loans individually evaluated for impairment	$ 496		$ 308
Period-end amount allocated to loans collectively evaluated for impairment	410		559
Total allocation	906	864	867	767	744	926
Loans, ending balance: Loans individually evaluated for impairment	1,744		1,687
Loans, ending balance: Loans collectively evaluated for impairment	41,081		39,815
Total	42,825		41,502
Commercial and industrial [Member]
Allowance for loan losses, Additional information
Period-end amount allocated to loans individually evaluated for impairment	496		308
Period-end amount allocated to loans collectively evaluated for impairment			79
Total allocation	496	417	387	280	239	301
Loans, ending balance: Loans individually evaluated for impairment	686		592
Loans, ending balance: Loans collectively evaluated for impairment	2,960		3,138
Total	3,646		3,730
Commercial real estate [Member]
Allowance for loan losses, Additional information
Period-end amount allocated to loans individually evaluated for impairment
Period-end amount allocated to loans collectively evaluated for impairment	367		412
Total allocation	367	412	412	432	430	553
Loans, ending balance: Loans individually evaluated for impairment	1,058		1,095
Loans, ending balance: Loans collectively evaluated for impairment	31,303		29,102
Total	32,361		30,197
Consumer real estate [Member]
Allowance for loan losses, Additional information
Period-end amount allocated to loans individually evaluated for impairment
Period-end amount allocated to loans collectively evaluated for impairment	43		68
Total allocation	43	35	68	55	75	52
Loans, ending balance: Loans individually evaluated for impairment
Loans, ending balance: Loans collectively evaluated for impairment	4,951		5,586
Total	4,951		5,586
Consumer loans other [Member]
Allowance for loan losses, Additional information
Period-end amount allocated to loans individually evaluated for impairment
Period-end amount allocated to loans collectively evaluated for impairment
Total allocation						20
Loans, ending balance: Loans individually evaluated for impairment
Loans, ending balance: Loans collectively evaluated for impairment	1,867		1,989
Total	$ 1,867		$ 1,989