Pensions (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pension and Other Postretirement Benefit Contributions [Abstract]
Employer contributions made			$ 2,310	$ 2,366
U.S. Plans
Components of net periodic pension cost (benefit) of the plans
Service cost	$ 285	$ 224	853	671
Interest cost	1,138	1,204	3,365	3,611
Expected return on plan assets	(1,783)	(1,885)	(5,349)	(5,656)
Amortization of prior service cost	4	18	11	55
Net actuarial loss amortization	646	219	1,916	658
Settlement	480		480
Net periodic pension cost (benefit)	770	(220)	1,276	(661)
Pension and Other Postretirement Benefit Contributions [Abstract]
Employer contributions made			1,200
European Plans
Components of net periodic pension cost (benefit) of the plans
Service cost	72	83	217	255
Interest cost	309	404	920	1,220
Expected return on plan assets	(421)	(379)	(1,251)	(1,140)
Net actuarial loss amortization	54	60	163	182
Net periodic pension cost (benefit)	$ 14	$ 168	$ 49	$ 517