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Warrants and Derivative Liabilities - Additional Information (Detail) $ / shares in Units, $ in Thousands			1 Months Ended	3 Months Ended		6 Months Ended
	Dec. 19, 2014 $ / shares shares	Apr. 04, 2012 shares	Oct. 31, 2013 $ / shares	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Apr. 29, 2015 $ / shares	Nov. 13, 2014 shares / pure $ / shares shares
Derivative [Line Items]
Gain (loss) in change of fair value of derivative instruments and warrants (less than $0.1 million for three months ended 2015) | $				$ 1,244	$ 701	$ 567	$ 1,501
Sale of stock, price per share (in dollars per share)								$ 6.00
Hercules Warrants
Derivative [Line Items]
Gain (loss) in change of fair value of derivative instruments and warrants (less than $0.1 million for three months ended 2015) | $				100	100	100	100
November 2014 Warrant
Derivative [Line Items]
Warrant exercise price (in dollars per share)								9.41
Gain (loss) in change of fair value of derivative instruments and warrants (less than $0.1 million for three months ended 2015) | $				900	500	$ 300	1,200
Warrants expiration date						Nov. 13, 2019
Common stock units offered (in shares) | shares									909,090
Warrants to purchase one share of common stock									0.9
Number of warrants issued to purchase common stock (in shares) | shares									818,181
Sale of stock, price per share (in dollars per share)									$ 11.00
Capital Ventures International | Exchanged Warrants
Derivative [Line Items]
Gain (loss) in change of fair value of derivative instruments and warrants (less than $0.1 million for three months ended 2015) | $				$ 200	$ 100	$ 200	$ 200
Senior Convertible Note warrant | Capital Ventures International | Original Warrants
Derivative [Line Items]
Number of shares received from warrants received to purchase common stock (in shares) | shares		309,406
Senior Convertible Note warrant | Capital Ventures International | Exchanged Warrants
Derivative [Line Items]
Warrant exercise, waiting period			6 months
Warrant exercise period			5 years
Warrant exercise price (in dollars per share)			$ 15.94
Senior Convertible Note warrant | Capital Ventures International | Maximum | Exchanged Warrants
Derivative [Line Items]
Beneficial ownership limitation percentage			4.99%
Beneficial ownership, limitation option, percentage			9.99%
Required notification period			61 days
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) | shares	58,823
Warrant exercise price (in dollars per share)	$ 11.00							$ 9.41
Warrants expiration date						Jun. 30, 2020

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Regulation S-X (SX)
-Number 210
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-Section 13
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(4))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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