Securities - Amortized cost and fair value of securities available for sale by contractual maturity (Details) $ in Thousands	Mar. 31, 2016 USD ($)
Amortized Cost
Due in one year or less	$ 482
Due after one year through five years	10,142
Due after five years through ten years	25,249
Due after ten years	129,552
Amortized cost	372,310
Fair Value
Due in one year or less	482
Due after one year through five years	10,412
Due after five years through ten years	24,994
Due after ten years	131,386
Fair value	377,025
Mortgage-backed securities [Member]
Amortized Cost
Amortized cost	147,301
Fair Value
Fair value	150,655
Other asset backed securities [Member]
Amortized Cost
Amortized cost	59,584
Fair Value
Fair value	$ 59,096