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Nature of Business, Basis of Presentation and Going Concern Uncertainty - Additional Information (Detail) $ in Thousands |  | 3 Months Ended | 9 Months Ended |
--- | --- | --- | --- | ---
May 23, 2018 | Sep. 30, 2019 USD ($) | Jun. 30, 2019 USD ($) | Mar. 31, 2019 USD ($) | Sep. 30, 2018 USD ($) | Jun. 30, 2018 USD ($) | Mar. 31, 2018 USD ($) | Sep. 30, 2019 USD ($) | Sep. 30, 2018 USD ($) | Dec. 31, 2018 USD ($)
Accounting Policies [Abstract] |  |  |  |  |  |  |  |  |  |
Reverse stock split ratio | 0.1 |  |  |  |  |  |  |  |  |
Accumulated deficit |  | $ (42,510) |  |  |  |  |  | $ (42,510) |  | $ (25,381)
Net loss |  | (3,673) | $ (3,624) | $ (5,904) | $ (3,240) | $ (2,788) | $ (3,022) | (13,201) | $ (9,050) |
Cash and cash equivalents |  | 7,375 |  |  |  |  |  | 7,375 |  | $ 9,515
Working capital |  | $ 4,500 |  |  |  |  |  | 4,500 |  |
Net cash used in operations |  |  |  |  |  |  |  | $ 11,802 | $ 7,082 |

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