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Nature of Business - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands |  |  |  | 1 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | --- | ---
Sep. 29, 2016 | Dec. 03, 2014 | May 13, 2011 | Jan. 31, 2015 | Dec. 31, 2016 | Dec. 31, 2015
Nature Of Business And Basis Of Presentation [Line Items] |  |  |  |  |  |
Proceeds from issuance of issuance of common stock, preferred stock and warrants, net of issuance costs | $ 27,600 |  |  |  | $ 27,630 |
Accumulated deficit |  |  |  |  | $ (181,773) | $ (165,565)
Net proceeds from initial public offering |  | $ 61,300 |  |  |  |
ProChon [Member] |  |  |  |  |  |
Nature Of Business And Basis Of Presentation [Line Items] |  |  |  |  |  |
Business acquisition date |  |  |  |  | May 13, 2011 |
Consideration paid to acquisition |  |  | $ 2,200 |  |  |
IPO [Member] |  |  |  |  |  |
Nature Of Business And Basis Of Presentation [Line Items] |  |  |  |  |  |
Sale of common stock shares |  | 5,909,091 |  |  |  |
Initial public offering price per share |  | $ 11.00 |  |  |  |
Gross proceeds from initial public offering |  | $ 65,000 |  |  |  |
Overallotment Option [Member] |  |  |  |  |  |
Nature Of Business And Basis Of Presentation [Line Items] |  |  |  |  |  |
Sale of common stock shares |  |  |  | 465,000 |  |
Initial public offering price per share |  |  |  | $ 11.00 |  |
Gross proceeds from initial public offering |  |  |  | $ 5,100 |  |

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