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Fair Value Measurements - Assumptions Used in Valuing Derivative Liabilities (Detail)	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
2012 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Risk-free interest rate	1.07%	0.68%	0.60%
Expected life	2 months 13 days	1 year 2 months 13 days	2 years 2 months 13 days
Volatility	79.00%	89.00%	75.00%
2013 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Risk-free interest rate	1.07%	0.68%	0.60%
Expected life	3 months 19 days	1 year 3 months 19 days	2 years 3 months 19 days
Volatility	79.00%	89.00%	75.00%

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Period the instrument, asset or liability is expected to be outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
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-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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Measure of dispersion, in percentage terms (for instance, the standard deviation or variance), for a given stock price.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
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Risk-free interest rate assumption used in valuing an instrument.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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