Property, Plant and Equipment (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 163,057	$ 153,034
Less accumulated depreciation	(105,904)	(96,478)
Property, plant and equipment, net	57,153	56,556
Depreciation and amortization expense	10,608	10,607	10,790
Future machinery and equipment purchase commitments	1,995	3,042
Land and Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,418	1,418
Building [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	14,945	14,410
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	142,826	134,168
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 3,868	$ 3,038