Loans, net and allowance for loan losses - Information Concerning Nonaccrual Loans by Major Loan Classification (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due
Nonaccrual loans, Total	$ 9,261	$ 11,108
Commercial
Financing Receivable, Recorded Investment, Past Due
Nonaccrual loans, Total	1,532	934
Real estate Commercial
Financing Receivable, Recorded Investment, Past Due
Nonaccrual loans, Total	4,701	7,016
Real estate Residential
Financing Receivable, Recorded Investment, Past Due
Nonaccrual loans, Total	2,821	3,003
Consumer
Financing Receivable, Recorded Investment, Past Due
Nonaccrual loans, Total	$ 207	$ 155