Stockholders' Equity - Stock Option Fair Value Assumptions (Detail)	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Expected volatility, Minimum	82.70%	103.70%	103.70%
Expected volatility, Maximum	84.10%	108.70%	108.00%
Weighted-average volatility	83.70%	107.90%	107.70%
Average expected term in years	5 years 4 months 24 days	5 years 9 months 18 days	5 years 9 months 18 days
Expected risk-free interest rate (zero coupon U.S. Treasury Note), Minimum	0.80%	0.90%	1.10%
Expected risk-free interest rate (zero coupon U.S. Treasury Note), Maximum	1.70%	1.30%	2.50%
Expected dividend yield	0.00%	0.00%	0.00%