Property Plant and Equipment, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 438,063	$ 402,887
Less accumulated depreciation	(252,611)	(226,366)
Property, plant and equipment, net	185,452	176,521
Depreciation expense	27,700	27,500	$ 24,100
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	15,163	14,921
Buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	104,763	97,265
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	20,746	20,068
Machinery, office furniture and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	269,417	249,068
Construction in process
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	27,974	21,565
ERP systems
Property, Plant and Equipment [Line Items]
Depreciation expense	3,300	3,900	3,800
Total expenses incurred	1,200	2,000	1,200
Total capital expenditures	3,600	4,100	6,400
Capital expenditures total to date	48,200
Assets held under capital lases
Property, Plant and Equipment [Line Items]
Depreciation expense	400	300	$ 100
Capital leased assets	7,200	3,600
Capital leases accumulated depreciation	$ 800	$ 400