Loans and allowance for loan losses (Details 1) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	$ 705,447	$ 677,006	$ 579,257
Pass
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	689,834	660,090
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	7,500	7,805
Substandard
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	5,109	6,163
Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	3,004	2,948
Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	234,362	223,030	215,899
Commercial real estate | Construction
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	9,131	12,870
Commercial real estate | Construction | Pass
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	9,131	12,870
Commercial real estate | Construction | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	0	0
Commercial real estate | Construction | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	0	0
Commercial real estate | Construction | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	0	0
Commercial real estate | Non-residential
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	206,736	197,499
Commercial real estate | Non-residential | Pass
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	196,250	186,020
Commercial real estate | Non-residential | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	6,804	6,840
Commercial real estate | Non-residential | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	3,682	4,639
Commercial real estate | Non-residential | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	0	0
Commercial real estate | Multifamily
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	18,495	12,661
Commercial real estate | Multifamily | Pass
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	18,102	12,261
Commercial real estate | Multifamily | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	0	0
Commercial real estate | Multifamily | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	393	400
Commercial real estate | Multifamily | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	0	0
Residential
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	40,793	43,534	41,482
Residential | Pass
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	38,510	41,249
Residential | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	0	0
Residential | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	0	0
Residential | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	2,283	2,285
Consumer
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	29,771	30,095	29,895
Consumer | Indirect automobile
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	316,866	297,144	223,653
Consumer | Indirect automobile | Pass
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	316,342	296,692
Consumer | Indirect automobile | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	0	0
Consumer | Indirect automobile | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	0	0
Consumer | Indirect automobile | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	524	452
Consumer | Home equity
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	19,132	19,269
Consumer | Home equity | Pass
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	18,939	19,071
Consumer | Home equity | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	0	0
Consumer | Home equity | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	0	0
Consumer | Home equity | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	193	198
Consumer | Other consumer
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	10,639	10,826
Consumer | Other consumer | Pass
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	10,635	10,816
Consumer | Other consumer | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	0	0
Consumer | Other consumer | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	0	0
Consumer | Other consumer | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	4	10
Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	83,655	83,203	$ 68,328
Commercial and industrial | Pass
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	81,925	81,111
Commercial and industrial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	696	965
Commercial and industrial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	1,034	1,124
Commercial and industrial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total gross loans	$ 0	$ 3