Property, Plant and Equipment, Net - Summary (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment, Gross [Abstract]
Property, plant and equipment, at cost	$ 380,640	$ 343,142
Accumulated depreciation	(226,581)	(196,251)
Accumulated depreciation of capital leases	(239)	(2,915)
Capital Leases, Balance Sheet, Assets by Major Class, Net [Abstract]
Property and equipment, net excluding work in progress	153,820	143,976
Construction in progress	16,512	16,819
Total property, plant and equipment, net	170,332	160,795
Land
Property, Plant and Equipment, Gross [Abstract]
Property, plant and equipment, at cost	4,289	3,981
Land | Assets Held Under Capital Leases
Property, Plant and Equipment, Gross [Abstract]
Property, plant and equipment, at cost	241	226
Buildings and improvements
Property, Plant and Equipment, Gross [Abstract]
Property, plant and equipment, at cost	$ 84,337	74,397
Buildings and improvements | Minimum
Capital Leases, Balance Sheet, Assets by Major Class, Net [Abstract]
Property, plant and equipment useful life	10 years
Buildings and improvements | Maximum
Capital Leases, Balance Sheet, Assets by Major Class, Net [Abstract]
Property, plant and equipment useful life	35 years
Buildings and improvements | Assets Held Under Capital Leases
Property, Plant and Equipment, Gross [Abstract]
Property, plant and equipment, at cost	$ 221	4,806
Buildings and improvements | Assets Held Under Capital Leases | Minimum
Capital Leases, Balance Sheet, Assets by Major Class, Net [Abstract]
Property, plant and equipment useful life	10 years
Buildings and improvements | Assets Held Under Capital Leases | Maximum
Capital Leases, Balance Sheet, Assets by Major Class, Net [Abstract]
Property, plant and equipment useful life	35 years
Machinery and equipment
Property, Plant and Equipment, Gross [Abstract]
Property, plant and equipment, at cost	$ 254,881	226,675
Machinery and equipment | Minimum
Capital Leases, Balance Sheet, Assets by Major Class, Net [Abstract]
Property, plant and equipment useful life	5 years
Machinery and equipment | Maximum
Capital Leases, Balance Sheet, Assets by Major Class, Net [Abstract]
Property, plant and equipment useful life	25 years
Machinery and equipment | Assets Held Under Capital Leases
Property, Plant and Equipment, Gross [Abstract]
Property, plant and equipment, at cost	$ 1,051	0
Office equipment
Property, Plant and Equipment, Gross [Abstract]
Property, plant and equipment, at cost	$ 33,880	31,504
Office equipment | Minimum
Capital Leases, Balance Sheet, Assets by Major Class, Net [Abstract]
Property, plant and equipment useful life	2 years
Office equipment | Maximum
Capital Leases, Balance Sheet, Assets by Major Class, Net [Abstract]
Property, plant and equipment useful life	8 years
Office equipment | Assets Held Under Capital Leases
Property, Plant and Equipment, Gross [Abstract]
Property, plant and equipment, at cost	$ 34	0
Vehicles
Property, Plant and Equipment, Gross [Abstract]
Property, plant and equipment, at cost	$ 1,706	$ 1,553
Vehicles | Minimum
Capital Leases, Balance Sheet, Assets by Major Class, Net [Abstract]
Property, plant and equipment useful life	3 years
Vehicles | Maximum
Capital Leases, Balance Sheet, Assets by Major Class, Net [Abstract]
Property, plant and equipment useful life	6 years