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Fair Value Measurements - Additional Information (Detail) | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Sep. 30, 2015 USD ($) shares | Sep. 30, 2014 USD ($) | Sep. 30, 2013 USD ($) | Sep. 30, 2011 shares | Jan. 31, 2013 shares | Dec. 31, 2012 shares | Jun. 30, 2010 shares
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |  |  |  |
Short term investments | $ | $ 17,539,902 | $ 21,653,032 |  |  |  |  |
Fair value of investment | $ | $ 17,234,960 | 44,333,855 |  |  |  |  |
Warrants outstanding | 1,490,761 |  |  |  |  |  |
Non-cash gain (loss) from change in fair value of the derivative liability | $ | $ 2,684,712 | (5,821,796) | $ 5,066,591 |  |  |  |
Duration of exchange rights | 7 years |  |  |  |  |  |
Ablaris Therapeutics |  |  |  |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |  |  |  |
Warrants outstanding | 500,000 |  |  |  |  |  |
Non-cash gain (loss) from change in fair value of the derivative liability | $ | $ 184,555 | $ (211,860) | $ 5,806 |  |  |  |
Exchange right convertible conversion ratio for first year | 0.06 |  |  |  |  |  |
Exchange right convertible conversion ratio for second year | 0.04 |  |  |  |  |  |
Exchange right convertible conversion ratio for third year | 0.03 |  |  |  |  |  |
Exchange right convertible conversion ratio for fourth year | 0.02 |  |  |  |  |  |
Exchange right convertible conversion ratio for fifth year and beyond | 0.01 |  |  |  |  |  |
Number of exchange right sold |  |  |  | 675,000 |  |  |
2010 Warrants |  |  |  |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |  |  |  |
Warrants issued to acquire Common Stock |  |  |  |  |  |  | 329,649
Warrants outstanding | 24,324 |  |  |  |  |  |
2012 Warrants |  |  |  |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |  |  |  |
Warrants issued to acquire Common Stock |  |  |  |  |  | 912,543 |
Warrants outstanding | 265,161 |  |  |  |  |  |
2013 Warrants |  |  |  |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |  |  |  |
Warrants issued to acquire Common Stock |  |  |  |  | 833,530 |  |
Warrants outstanding | 12,123 |  |  |  |  |  |

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