Property, Plant and Equipment - Summary of Property Plant and Equipment (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Property, Plant and Equipment [Line Items]
Gross Total	$ 312,374	$ 242,279
Less: accumulated depreciation	(95,927)	(78,130)
Accumulated depreciation on equipment under capital lease	(3,312)	(2,414)
Property, plant and equipment, net	229,632	182,663
Buildings and related structures [Member]
Property, Plant and Equipment [Line Items]
Gross Total	76,310	73,021
Machinery and equipment [Member]
Property, Plant and Equipment [Line Items]
Gross Total	209,313	151,100
Vehicles and others [Member]
Property, Plant and Equipment [Line Items]
Gross Total	15,087	11,998
Equipment under capital lease [Member]
Property, Plant and Equipment [Line Items]
Gross Total	11,664	11,160
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	16,422	15,928
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	$ 75