Loans and Allowance for Loan Losses (Analysis of allowance for loan losses - Additional information) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Jun. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Dec. 31, 2010
Allowance for loan losses, Additional information
Period-end amount allocated to loans individually evaluated for impairment	$ 503		$ 308
Period-end amount allocated to loans collectively evaluated for impairment	366		559
Total allocation	869	906	867	799	767	926
Loans, ending balance: Loans individually evaluated for impairment	1,746		1,687
Loans, ending balance: Loans collectively evaluated for impairment	38,927		39,815
Total	40,673		41,502
Commercial and industrial [Member]
Allowance for loan losses, Additional information
Period-end amount allocated to loans individually evaluated for impairment	503		308
Period-end amount allocated to loans collectively evaluated for impairment			79
Total allocation	503	496	387	295	280	301
Loans, ending balance: Loans individually evaluated for impairment	626		592
Loans, ending balance: Loans collectively evaluated for impairment	3,267		3,138
Total	3,893		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	364		412
Total allocation	364	367	412	433	432	553
Loans, ending balance: Loans individually evaluated for impairment	1,120		1,095
Loans, ending balance: Loans collectively evaluated for impairment	29,019		29,102
Total	30,139		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	2		68
Total allocation	2	43	68	71	55	52
Loans, ending balance: Loans individually evaluated for impairment
Loans, ending balance: Loans collectively evaluated for impairment	4,806		5,586
Total	4,806		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	1,835		1,989
Total	$ 1,835		$ 1,989