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Warrants and Derivative Liabilities - Additional Information (Detail) - USD ($) |  |  |  |  |  |  |  | 1 Months Ended | 3 Months Ended | 6 Months Ended
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Apr. 29, 2015 | Dec. 19, 2014 | Nov. 13, 2014 | Nov. 15, 2013 | Oct. 09, 2013 | Jun. 05, 2012 | Apr. 04, 2012 | Dec. 31, 2012 | Sep. 30, 2015 | Dec. 31, 2014 | Sep. 30, 2014 | Dec. 31, 2013 | Sep. 30, 2015 | Sep. 30, 2014
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Exercise price | $ 9.41 |  |  |  |  |  |  |  |  |  |  |  |  |
Warrants to purchase one share of common stock |  |  | 90.00% |  |  |  |  |  |  |  |  |  |  |
Gain (loss) in change of fair value of derivative instruments and warrants |  |  |  |  |  |  |  |  | $ 701,000 |  | $ 795,000 |  | $ 1,501,000 | $ 760,000
Warrants expiration date |  |  | Nov. 13, 2019 | May 15, 2019 |  | Dec. 05, 2017 |  |  |  |  |  |  |  |
Common stock units offered |  |  | 909,090 |  |  |  |  |  |  |  |  |  |  |
Number of warrants issued to purchase common stock |  |  | 818,181 |  |  |  |  |  |  |  |  |  |  |
Sale of stock, price per share |  |  | $ 11.00 |  |  |  |  |  |  |  |  |  |  |
Senior Secured Term Loan First Warrant |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gain (loss) in change of fair value of derivative instruments and warrants |  |  |  |  |  |  |  |  |  |  | 0 |  |  | 0
Senior Secured Term Loan New Warrant |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gain (loss) in change of fair value of derivative instruments and warrants |  |  |  |  |  |  |  |  |  |  |  |  | 100,000 |
Hudson Warrant |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gain (loss) in change of fair value of derivative instruments and warrants |  |  |  |  |  |  |  |  | 500,000 |  |  |  | $ 1,200,000 |
Maximum | Senior Secured Term Loan New Warrant |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gain (loss) in change of fair value of derivative instruments and warrants |  |  |  |  |  |  |  |  | 100,000 |  |  |  |  |
Capital Ventures International |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Warrant exercise, waiting period |  |  |  |  |  |  |  |  |  |  |  |  | 6 months |
Warrant exercise period |  |  |  |  |  |  |  |  |  |  |  |  | 5 years |
Common stock, shares issued |  |  |  |  |  |  |  |  |  | 909,090 |  |  |  |
Warrants to purchase one share of common stock |  |  |  |  |  |  |  |  |  | 90.00% |  |  |  |
Required notification period |  |  |  |  |  |  |  |  |  |  |  |  | 61 days |
Gain (loss) in change of fair value of derivative instruments and warrants |  |  |  |  |  |  |  |  | $ 100,000 |  | 800,000 |  | $ 200,000 | 700,000
Senior Convertible Debt | Capital Ventures International |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares received from warrants received to purchase common stock |  |  |  |  |  |  | 309,406 |  |  |  |  |  |  |
Exercise price | 15.94 |  |  |  | $ 26.10 |  | $ 54.50 |  |  | $ 22.10 |  |  |  |
New Unsecured Senior Convertible Note | Capital Ventures International | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Beneficial ownership limitation percentage |  |  |  |  |  |  |  | 4.99% |  |  |  |  |  |
New Unsecured Senior Convertible Note | Capital Ventures International | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Beneficial ownership limitation percentage |  |  |  |  |  |  |  | 9.99% |  |  |  |  |  |
Senior Secured Loan |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares received from warrants received to purchase common stock |  |  |  | 25,641 |  |  |  |  |  |  |  |  |  |
Exercise price |  |  | $ 17.00 | $ 19.50 |  |  |  |  |  |  |  |  |  |
Common stock, shares issued |  |  | 909,090 |  |  |  |  |  |  |  |  |  |  |
Warrants to purchase one share of common stock |  |  | 90.00% |  |  |  |  |  |  |  |  |  |  |
Gain (loss) in change of fair value of derivative instruments and warrants |  |  |  |  |  |  |  |  |  |  | $ 100,000 |  |  | $ 100,000
Senior Secured Loan | Hercules Technology Growth Capital |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares received from warrants received to purchase common stock |  | 58,823 |  |  |  |  |  |  |  |  |  |  |  |
Exercise price | $ 9.41 | $ 11.00 | $ 17.00 |  |  |  |  |  |  |  |  | $ 19.50 |  |
Common stock, shares issued |  |  | 909,090 |  |  |  |  |  |  |  |  |  |  |
Warrants to purchase one share of common stock |  |  | 90.00% |  |  |  |  |  |  |  |  |  |  |
Warrants expiration date |  | Jun. 30, 2020 |  |  |  |  |  |  |  |  |  |  |  |
Senior Secured Loan | Term Loan | Hercules Technology Growth Capital |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares received from warrants received to purchase common stock |  |  |  |  |  | 13,927 |  |  |  |  |  |  |  |
Exercise price |  |  |  |  |  | $ 35.90 |  |  |  |  |  |  |  |

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