Property, Plant and Equipment, net (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Property, Plant and Equipment, net
Property, plant and equipment, gross	$ 213,265		$ 213,265		$ 199,972
Accumulated depreciation and amortization	(137,047)		(137,047)		(126,823)
Property, plant and equipment, net	76,218		76,218		73,149
Depreciation expense	5,600	$ 6,200	11,100	$ 11,800
Land
Property, Plant and Equipment, net
Property, plant and equipment, gross	1,893		1,893		1,714
Buildings and improvements
Property, Plant and Equipment, net
Property, plant and equipment, gross	21,864		$ 21,864		19,261
Buildings and improvements | Minimum
Property, Plant and Equipment, net
Useful Life (Years)			30 years
Buildings and improvements | Maximum
Property, Plant and Equipment, net
Useful Life (Years)			40 years
Office furniture and equipment
Property, Plant and Equipment, net
Property, plant and equipment, gross	13,335		$ 13,335		12,574
Office furniture and equipment | Minimum
Property, Plant and Equipment, net
Useful Life (Years)			5 years
Office furniture and equipment | Maximum
Property, Plant and Equipment, net
Useful Life (Years)			8 years
Machinery and equipment
Property, Plant and Equipment, net
Property, plant and equipment, gross	$ 176,173		$ 176,173		$ 166,423
Machinery and equipment | Minimum
Property, Plant and Equipment, net
Useful Life (Years)			5 years
Machinery and equipment | Maximum
Property, Plant and Equipment, net
Useful Life (Years)			7 years