Property Plant and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Land	$ 11,520	$ 7,883
Buildings and Improvements, Gross	115,270	114,522
Machinery and Equipment, Gross	261,723	256,742
Property, Plant and Equipment, Gross	388,513	379,147
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(265,415)	(249,265)
Property, Plant and Equipment, Net	$ 123,098	$ 129,882	$ 143,211