Acquisition - Additional information (Detail)				9 Months Ended
	Sep. 30, 2013 USD ($)	Apr. 11, 2013 USD ($)	Dec. 31, 2012 USD ($)	Sep. 30, 2013 Orbital Gas Systems Limited USD ($)	Sep. 30, 2013 Orbital Gas Systems Limited GBP (£)
Business Acquisition [Line Items]
Business combination percentage equity interest in acquire				100.00%	100.00%
Common stock, par value	$ 0.001	$ 0.001	$ 0.001
Business Acquisition of Description obligations of purchase price				5.0% of the purchase price, or 850,000, is held in escrow to and through December 1, 2013	5.0% of the purchase price, or 850,000, is held in escrow to and through December 1, 2013
Business acquisition cost acquired purchase price				$ 26,205,500	£ 17,000,000