Property, Plant and Equipment by Classification (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 92,283	$ 90,395
Less accumulated depreciation and amortization	(14,151)	(13,302)
Property, plant and equipment, net	78,132	77,093
Construction in progress
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	58,503	57,185
Plant machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	10 years
Total property, plant and equipment	11,030	11,030
Site improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	10 years
Total property, plant and equipment	7,007	7,007
Lab equipment, furniture and fixtures and vehicles
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	5 years
Total property, plant and equipment	6,111	5,553
Demonstration plant
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	2 years
Total property, plant and equipment	3,597	3,597
Buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	10 years
Total property, plant and equipment	2,543	2,543
Computer, office equipment and software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Total property, plant and equipment	1,412	1,411
Leasehold improvements, pilot plant, land and support equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 2,080	$ 2,069
Leasehold improvements, pilot plant, land and support equipment | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	0 years
Leasehold improvements, pilot plant, land and support equipment | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	5 years