Premises and equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Total premises and equipment	$ 21,052	$ 21,511
Less: Accumulated depreciation and amortization	(8,294)	(7,840)
Premises and equipment, net	12,758	13,671
Land [Member]
Property, Plant and Equipment [Line Items]
Total premises and equipment	4,352	4,858
Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Total premises and equipment	9,087	9,216
Furniture Fixtures And Equipments [Member]
Property, Plant and Equipment [Line Items]
Total premises and equipment	$ 7,613	$ 7,437