Investment securities available for sale (Details 1) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Schedule of Available-for-sale Securities [Line Items]        
Gross realized gains $ 0 $ 15 $ 0 $ 162
Gross realized losses 0 0 (9) 0
Available-for-sale Securities, Gross Realized Gain (Loss), Total $ 0 $ 15 $ (9) $ 162