Loans, net and allowance for loan losses - Major Classification of Loans by Past Due Status (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment, Past Due
Total Past Due	$ 11,987	$ 15,392
Current	1,869,103	1,807,874
Total Loans	1,881,090	1,823,266
Loans > 90 Days and Accruing	386	923
30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	1,876	6,104
60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	1,326	2,134
Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due
Total Past Due	8,785	7,154
Commercial
Financing Receivable, Recorded Investment, Past Due
Total Past Due	3,430	1,828
Current	494,555	492,306
Total Loans	497,985	494,134
Loans > 90 Days and Accruing	53
Commercial \| 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	9	973
Commercial \| 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	25	79
Commercial \| Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due
Total Past Due	3,396	776
Real estate Commercial
Financing Receivable, Recorded Investment, Past Due
Total Past Due	4,235	4,843
Current	972,023	902,960
Total Loans	976,258	907,803
Loans > 90 Days and Accruing	54	73
Real estate Commercial \| 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	776	1,889
Real estate Commercial \| 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	159	218
Real estate Commercial \| Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due
Total Past Due	3,300	2,736
Real estate Residential
Financing Receivable, Recorded Investment, Past Due
Total Loans	299,209	299,876
Real estate Residential
Financing Receivable, Recorded Investment, Past Due
Total Past Due	3,479	7,461
Current	295,730	292,415
Total Loans	299,209	299,876
Loans > 90 Days and Accruing	279	850
Real estate Residential \| 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	656	2,486
Real estate Residential \| 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	996	1,545
Real estate Residential \| Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due
Total Past Due	1,827	3,430
Consumer
Financing Receivable, Recorded Investment, Past Due
Total Past Due	843	1,260
Current	106,795	120,193
Total Loans	107,638	121,453
Consumer \| 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	435	756
Consumer \| 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	146	292
Consumer \| Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due
Total Past Due	$ 262	$ 212

Amount of financing receivable 90 days or more past due and still accruing.

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