Property, Plant and Equipment, Net - Summary (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	$ 438,619	$ 380,640
Accumulated depreciation	(244,098)	(226,581)
Accumulated depreciation of capital leases	(608)	(239)
Property and equipment, net excluding work in progress	193,913	153,820
Construction in progress	19,456	16,512
Total property, plant and equipment, net	213,369	170,332
Depreciation expense	23,400	21,400	$ 17,800
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	6,280	4,289
Land | Assets Held Under Capital Leases
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	228	241
Buildings and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	$ 104,036	84,337
Buildings and improvements | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life	10 years
Buildings and improvements | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life	35 years
Buildings and improvements | Assets Held Under Capital Leases
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	$ 229	221
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	$ 289,059	254,881
Machinery and equipment | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life	5 years
Machinery and equipment | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life	25 years
Machinery and equipment | Assets Held Under Capital Leases
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	$ 1,005	1,051
Office equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	$ 36,110	33,880
Office equipment | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life	2 years
Office equipment | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life	8 years
Office equipment | Assets Held Under Capital Leases
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	$ 32	34
Vehicles
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	$ 1,640	$ 1,706
Vehicles | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life	3 years
Vehicles | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life	6 years