Selected Quarterly Financial Data (unaudited) - (Details) - USD ($) $ / shares in Units, $ in Thousands |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2018 |
Sep. 30, 2018 |
Jun. 30, 2018 |
Mar. 31, 2018 |
Dec. 31, 2017 |
Sep. 30, 2017 |
Jun. 30, 2017 |
Mar. 31, 2017 |
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
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| Quarterly Financial Information Disclosure [Abstract] | |||||||||||
| Revenue | $ 893 | $ 412 | $ 375 | $ 370 | $ 1,101 | $ 2,050 | $ 1,101 | $ 317 | |||
| Operating expenses: | |||||||||||
| Research and development | 15,128 | 12,856 | 11,082 | 11,116 | $ 11,780 | $ 10,447 | $ 10,041 | 9,628 | 50,182 | 41,896 | 37,817 |
| General and administrative | 4,372 | 3,876 | 3,841 | 4,075 | 3,740 | 3,593 | 3,472 | 3,086 | 16,164 | 13,891 | 10,463 |
| Total operating expenses | 19,500 | 16,732 | 14,923 | 15,191 | 15,520 | 14,040 | 13,513 | 12,714 | 66,346 | 55,787 | 48,280 |
| Loss from operations | (18,607) | (16,320) | (14,548) | (14,821) | (15,520) | (14,040) | (13,513) | (11,613) | (64,296) | (54,686) | (47,963) |
| Other income, net | 575 | 583 | 501 | 358 | 218 | 215 | 145 | 98 | 2,017 | 676 | 220 |
| Net loss applicable to common stockholders | $ (18,032) | $ (15,737) | $ (14,047) | $ (14,463) | $ (15,302) | $ (13,825) | $ (13,368) | $ (11,515) | $ (62,279) | $ (54,010) | $ (51,424) |
| Net loss per share applicable to common stockholders - basic and diluted | $ (0.54) | $ (0.47) | $ (0.43) | $ (0.48) | $ (0.58) | $ (0.53) | $ (0.52) | $ (0.49) | $ (1.91) | $ (2.13) | $ (4.05) |
| Weighted-average number of common shares used in net loss per share applicable to common stockholders - basic and diluted | 33,694,756 | 33,653,479 | 32,892,712 | 30,335,164 | 26,316,550 | 26,259,216 | 25,584,147 | 23,393,448 | 32,656,237 | 25,406,845 | 12,696,414 |
| X | ||||||||||
- Definition The amount of net income or loss for the period per each share in instances when basic and diluted earnings per share are the same amount and reported as a single line item on the face of the financial statements. Basic earnings per share is the amount of net income or loss for the period per each share of common stock or unit outstanding during the reporting period. Diluted earnings per share includes the amount of net income or loss for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition The aggregate total of expenses of managing and administering the affairs of an entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Generally recurring costs associated with normal operations except for the portion of these expenses which can be clearly related to production and included in cost of sales or services. Includes selling, general and administrative expense. No definition available.
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- References No definition available.
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- Definition The net result for the period of deducting operating expenses from operating revenues. No definition available.
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- Definition Amount of income (expense) related to nonoperating activities, classified as other. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- References No definition available.
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- Definition The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Average number of shares or units issued and outstanding that are used in calculating basic and diluted earnings per share (EPS). No definition available.
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