Loans and allowance for credit losses (Details 1) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	$ 40,578	$ 40,714
Loans collectively evaluated for impairment	669,081	671,205
Total loans	709,659	711,919
Allowance for credit losses allocated to:
Loans individually evaluated for impairment	625	783
Loans collectively evaluated for impairment	8,451	9,942
Total allowance for credit losses	9,076	10,725
Construction Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	11,878	5,569
Loans collectively evaluated for impairment	56,470	59,022
Total loans	68,348	64,591
Allowance for credit losses allocated to:
Loans individually evaluated for impairment	201	204
Loans collectively evaluated for impairment	2,047	1,756
Total allowance for credit losses	2,248	1,960
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	19,232	19,748
Loans collectively evaluated for impairment	257,952	255,109
Total loans	277,184	274,857
Allowance for credit losses allocated to:
Loans individually evaluated for impairment	310	285
Loans collectively evaluated for impairment	2,044	3,569
Total allowance for credit losses	2,354	3,854
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	9,126	14,462
Loans collectively evaluated for impairment	288,636	290,143
Total loans	297,762	304,605
Allowance for credit losses allocated to:
Loans individually evaluated for impairment	24	44
Loans collectively evaluated for impairment	2,628	2,985
Total allowance for credit losses	2,652	3,029
Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	317	887
Loans collectively evaluated for impairment	56,175	56,308
Total loans	56,492	57,195
Allowance for credit losses allocated to:
Loans individually evaluated for impairment	65	245
Loans collectively evaluated for impairment	793	1,021
Total allowance for credit losses	858	1,266
Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	25	48
Loans collectively evaluated for impairment	9,848	10,623
Total loans	9,873	10,671
Allowance for credit losses allocated to:
Loans individually evaluated for impairment	25	5
Loans collectively evaluated for impairment	281	238
Total allowance for credit losses	306	243
Unallocated Financing Receivables [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
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	658	373
Total allowance for credit losses	$ 658	$ 373