Property, Plant and Equipment, Net (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Property, Plant and Equipment
Property, plant and equipment, gross	$ 436,596	$ 438,490	$ 445,856
Less accumulated depreciation and amortization	(252,479)	(245,383)	(245,806)
Property, plant and equipment excluding capital projects in progress, net	184,117	193,107	200,050
Capital projects in progress	22,720	13,920	6,513
Property, plant and equipment, net	206,837	207,027	206,563
Land
Property, Plant and Equipment
Property, plant and equipment, gross	29,097	29,390	30,242
Buildings and site improvements
Property, Plant and Equipment
Property, plant and equipment, gross	173,070	175,058	177,604
Leasehold improvements
Property, Plant and Equipment
Property, plant and equipment, gross	5,616	5,602	5,531
Machinery, equipment, and software
Property, Plant and Equipment
Property, plant and equipment, gross	$ 228,813	$ 228,440	$ 232,479