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Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions |  |  | 1 Months Ended
--- | --- | --- | ---
May 26, 2017 | May 10, 2017 | May 26, 2017
Class of Stock [Line Items] |  |  |
Proceeds from additional equity offering |  |  | $ 17.0
Public stock offering |  |  |
Class of Stock [Line Items] |  |  |
Common stock, shares issued (in shares) |  | 4,000,000 |
Sale of stock, price per share (in dollars per share) |  | $ 4.00 |
Proceeds from additional equity offering |  | $ 14.7 |
Over-allotment option |  |  |
Class of Stock [Line Items] |  |  |
Common stock, shares issued (in shares) |  | 600,000 |
Proceeds from additional equity offering | $ 2.3 |  |
Over allotment common stock options period (in shares) |  | 30 days |
ATM issuance sales agreement |  |  |
Class of Stock [Line Items] |  |  |
Maximum value of shares for sale |  | $ 10.0 |

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