Property, Plant and Equipment, Net (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013
Property, Plant and Equipment
Property, plant and equipment, gross	$ 439,905	$ 438,782	$ 433,294
Less accumulated depreciation and amortization	(246,287)	(235,535)	(232,958)
Property, plant and equipment excluding capital projects in progress, net	193,618	203,247	200,336
Capital projects in progress	12,516	6,286	9,305
Property, plant and equipment, net	206,134	209,533	209,641
Land
Property, Plant and Equipment
Property, plant and equipment, gross	29,624	29,347	29,283
Buildings and site improvements
Property, Plant and Equipment
Property, plant and equipment, gross	174,343	178,391	177,484
Leasehold improvements
Property, Plant and Equipment
Property, plant and equipment, gross	5,404	5,213	5,068
Machinery, equipment, and software
Property, Plant and Equipment
Property, plant and equipment, gross	$ 230,534	$ 225,831	$ 221,459