Property, Plant and Equipment (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Property, plant and equipment
Land and land improvements	$ 5,006	$ 4,974
Buildings	43,411	41,433
Machinery and equipment	237,473	224,426
Construction-in-progress	7,493	12,446
Other	8,674	8,419
Property, plant and equipment, Gross	302,057	291,698
Accumulated depreciation	(151,760)	(141,458)
Property, plant and equipment, Net	$ 150,297	$ 150,240