Retirement Plans - Accumulated Other Comprehensive loss (Details 4) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
U.S.Pension Plans
Accumulated Other Comprehensive Loss
Beginning balance	$ 96,388	$ 96,194
Amortization of retirement benefits, net of tax	(3,817)	(3,956)
Settlements and curtailments	0	0
Net actuarial gain	(2,808)	4,150
Foreign exchange impact	0	0
Ending balance	89,763	96,388
U.S.Pension Plans | Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss)
Accumulated Other Comprehensive Loss
Beginning balance	96,388	96,194
Amortization of retirement benefits, net of tax	(3,817)	(3,956)
Settlements and curtailments	0	0
Net actuarial gain	(2,808)	4,150
Foreign exchange impact	0	0
Ending balance	89,763	96,388
U.S.Pension Plans | Accumulated Defined Benefit Plans Adjustment, Net Prior Service Cost (Credit)
Accumulated Other Comprehensive Loss
Beginning balance	0	0
Amortization of retirement benefits, net of tax	0	0
Settlements and curtailments	0	0
Net actuarial gain	0	0
Foreign exchange impact	0	0
Ending balance	0	0
Non-U.S. Pension Plans | Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss)
Accumulated Other Comprehensive Loss
Beginning balance	1,639	8,490
Amortization of retirement benefits, net of tax	85	(1,507)
Settlements and curtailments		(5,355)
Net actuarial gain	12	640
Foreign exchange impact	7	(629)
Ending balance	1,743	1,639
Post-Retirement Life Insurance Plan | Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss)
Accumulated Other Comprehensive Loss
Beginning balance	(669)	(517)
Amortization of retirement benefits, net of tax	95	63
Net actuarial gain	14	(215)
Ending balance	$ (560)	$ (669)