Weighted Average Assumptions Used to Estimate Fair Value of Stock Option Grants (Detail) (USD $)	6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Non-Statutory Stock Options
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Expected term (years)	7 years 1 month 6 days	7 years 6 months
Expected volatility	105.96%	95.71%
Risk-free interest rate	1.28%	1.47%
Expected dividends	$ 0	$ 0
Incentive Stock Options
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Expected term (years)	6 years 6 months
Expected volatility	110.53%
Risk-free interest rate	1.13%
Expected dividends	$ 0