Derivative Liability - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended		3 Months Ended			6 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012 Private_placement	Mar. 31, 2013	Sep. 30, 2013 Warrant [Member]	Sep. 30, 2012 Warrant [Member]	Dec. 31, 2011 Warrant [Member]	Sep. 30, 2013 Warrant [Member]	Sep. 30, 2012 Warrant [Member]	Dec. 31, 2012 Warrant [Member]
Derivative [Line Items]
Number of offerings under private placement reverse merger					3
Warrants Issued									1,500,000			21,347,182
Warrants maturity term					5 years
Fair value of the warrant liabilities									$ 1.3			$ 32.7
Estimated fair value of the outstanding warrant liabilities	0.8		0.8			6.9
Change in fair value of the derivative liabilities increase and decrease	$ 4.8	$ 42.3	$ 4.8	$ 8.3
Exercised derivative liabilities							1,782,928	1,668,475		1,817,928	1,768,475
Reclassification of warrant							269,657			269,657