Property and Equipment, Net - Property and Equipment Table (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 401,230	$ 392,930
Less: Accumulated depreciation	216,150	202,680
Property and equipment, net	185,080	190,250
Land and Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	15,580	15,500
Building [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	74,120	73,550
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 311,530	$ 303,880