Securities - Amortized cost and fair value of securities available for sale by contractual maturity (Details) $ in Thousands	Dec. 31, 2016 USD ($)
Amortized Cost [Abstract]
Due in one year or less	$ 777
Due after one year through five years	9,020
Due after five years through ten years	25,004
Due after ten years	118,289
Total	303,490
Fair Value [Abstract]
Due in one year or less	777
Due after one year through five years	9,219
Due after five years through ten years	24,174
Due after ten years	117,808
Total	301,567
Mortgage-backed securities [Member]
Amortized Cost [Abstract]
Total	108,540
Fair Value [Abstract]
Total	107,984
Other Asset Backed Securities [Member]
Amortized Cost [Abstract]
Total	41,860
Fair Value [Abstract]
Total	$ 41,605