Pension benefits (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation at beginning of the year	$ 2,840	$ 3,531	$ 3,652
Service cost	368	477	491
Interest cost	170	219	222
Actuarial gain	(197)	(1,119)	(855)
Foreign currency exchange rates changes	(142)	(199)	132
Benefits paid	(143)	(69)	(111)
Projected benefit obligation at end of the year	$ 2,896	$ 2,840	$ 3,531