Loans and allowance for credit losses (Details 1) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Loans individually evaluated for impairment	$ 48,060	$ 88,827
Loans collectively evaluated for impairment	670,567	696,255
Total loans	718,627	785,082
Allowance for credit losses allocated to:
Loans individually evaluated for impairment	2,167	2,201
Loans collectively evaluated for impairment	9,134	13,790
Total allowance for credit losses	11,301	15,991
Unallocated Financing Receivables [Member]
Loans individually evaluated for impairment	0	0
Loans collectively evaluated for impairment	0	0
Total loans	0	0
Allowance for credit losses allocated to:
Loans individually evaluated for impairment	0	0
Loans collectively evaluated for impairment	471	187
Total allowance for credit losses	471	187
Commercial Loan [Member]
Loans individually evaluated for impairment	952	715
Loans collectively evaluated for impairment	54,149	60,071
Total loans	55,101	60,786
Allowance for credit losses allocated to:
Loans individually evaluated for impairment	305	0
Loans collectively evaluated for impairment	967	1,682
Total allowance for credit losses	1,272	1,682
Consumer Loan [Member]
Loans individually evaluated for impairment	80	87
Loans collectively evaluated for impairment	11,168	13,206
Total loans	11,248	13,293
Allowance for credit losses allocated to:
Loans individually evaluated for impairment	61	48
Loans collectively evaluated for impairment	209	359
Total allowance for credit losses	270	407
Residential Real Estate [Member]
Loans individually evaluated for impairment	22,171	18,549
Loans collectively evaluated for impairment	257,982	269,462
Total loans	280,153	288,011
Allowance for credit losses allocated to:
Loans individually evaluated for impairment	924	598
Loans collectively evaluated for impairment	2,806	4,596
Total allowance for credit losses	3,730	5,194
Commercial Real Estate [Member]
Loans individually evaluated for impairment	14,919	32,447
Loans collectively evaluated for impairment	288,235	282,494
Total loans	303,154	314,941
Allowance for credit losses allocated to:
Loans individually evaluated for impairment	455	614
Loans collectively evaluated for impairment	3,113	3,520
Total allowance for credit losses	3,568	4,134
Construction Loans [Member]
Loans individually evaluated for impairment	9,938	37,029
Loans collectively evaluated for impairment	59,033	71,022
Total loans	68,971	108,051
Allowance for credit losses allocated to:
Loans individually evaluated for impairment	422	941
Loans collectively evaluated for impairment	1,568	3,446
Total allowance for credit losses	$ 1,990	$ 4,387