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Warrants and Derivative Liabilities - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands |  | 3 Months Ended | 6 Months Ended |  |
--- | --- | --- | --- | --- | ---
Dec. 19, 2014 | Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2018 | Sep. 30, 2017 | Mar. 31, 2018 | Nov. 13, 2014
Derivative [Line Items] |  |  |  |  |  |  |
Change in fair value of warrants and contingent consideration |  | $ 282 | $ 144 | $ (182) | $ 1,069 |  |
November 2014 Warrant |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |
Warrants expiration date |  |  |  | Nov. 13, 2019 |  |  |
Common stock units offered (in shares) |  |  |  |  |  |  | 909,090
Warrants to purchase one share of common stock (in shares) |  |  |  |  |  |  | 0.9
Number of warrants issued to purchase common stock (in shares) |  |  |  |  |  |  | 818,181
Sale of stock, price per share (in dollars per share) |  |  |  |  |  |  | $ 7.81
Change in fair value of warrants and contingent consideration |  | $ 300 | $ 100 | $ (200) | $ 1,000 |  |
Senior secured loan | Hercules Technology Growth Capital | First Warrant |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |
Number of shares received from warrants received to purchase common stock (in shares) |  |  |  | 13,927 |  |  |
Senior secured loan | Hercules Technology Growth Capital | Second Warrant |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |
Number of shares received from warrants received to purchase common stock (in shares) |  |  |  | 25,641 |  |  |
Senior secured loan | Hercules Technology Growth Capital | Hercules Warrants |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |
Number of shares received from warrants received to purchase common stock (in shares) | 58,823 |  |  |  |  |  |
Warrant exercise price (in dollars per share) |  | $ 7.85 |  | $ 7.85 |  |  |
Warrants expiration date |  |  |  | Jun. 30, 2020 |  |  |
Warrant fair value |  | $ 100 |  | $ 100 |  | $ 100 |

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