Property, Plant and Equipment (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011
Property, Plant, and Equipment Disclosure [Line Items]
Property, plant and equipment, gross	$ 49,851	$ 50,914
Less: Accumulated depreciation	(37,170)	(36,514)
Property, plant and equipment, excluding construction in progress, net	12,681	14,400
Construction in progress	397	546
Total	13,078	14,946
Transportation property and equipment
Property, Plant, and Equipment Disclosure [Line Items]
Estimated Useful Life (in years)	3 years
Property, plant and equipment, gross	10,140	10,140
Machinery and Equipment
Property, Plant, and Equipment Disclosure [Line Items]
Property, plant and equipment, gross	18,639	18,978
Machinery and Equipment | Minimum
Property, Plant, and Equipment Disclosure [Line Items]
Estimated Useful Life (in years)	3 years
Machinery and Equipment | Maximum
Property, Plant, and Equipment Disclosure [Line Items]
Estimated Useful Life (in years)	10 years
Office equipment
Property, Plant, and Equipment Disclosure [Line Items]
Property, plant and equipment, gross	19,346	19,845
Office equipment | Minimum
Property, Plant, and Equipment Disclosure [Line Items]
Estimated Useful Life (in years)	5 years
Office equipment | Maximum
Property, Plant, and Equipment Disclosure [Line Items]
Estimated Useful Life (in years)	10 years
Autos and trucks
Property, Plant, and Equipment Disclosure [Line Items]
Property, plant and equipment, gross	$ 1,726	$ 1,951
Autos and trucks | Minimum
Property, Plant, and Equipment Disclosure [Line Items]
Estimated Useful Life (in years)	5 years
Autos and trucks | Maximum
Property, Plant, and Equipment Disclosure [Line Items]
Estimated Useful Life (in years)	10 years