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Income Taxes - Additional Information (Detail) - USD ($) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Income Tax Disclosure [Line Items] |  |  |
Income tax benefits for the net operating losses | $ 0 | $ 0 |
Valuation allowance | $ 53,834,000 | 40,290,000 | $ 26,515,000
Description of tax benefit likely to be realized upon settlement | greater than 50% |  |
Unrecognized tax benefits | $ 0 |  |
Income tax examination description | In the normal course of business, the Company is subject to examination by federal and state jurisdictions, where applicable. There are currently no pending tax examinations. Tax years from 2016 to the present are open to examination under the statute. |  |
Interest or penalties accrued | $ 0 | 0 |
Federal |  |  |
Income Tax Disclosure [Line Items] |  |  |
Net operating loss carryforwards | 172,900,000 | 125,500,000 |
Net operating loss carryforwards subject to expiration | 79,400,000 |  |
Net operating loss carryforwards not subject to expiration | $ 93,500,000 |  |
Net operating loss carryforwards expiration year | 2034 |  |
Federal | Research and Development. |  |  |
Income Tax Disclosure [Line Items] |  |  |
Tax credit carryforwards | $ 2,500,000 |  |
State |  |  |
Income Tax Disclosure [Line Items] |  |  |
Net operating loss carryforwards | $ 159,000,000 | $ 109,400,000 |
Net operating loss carryforwards expiration year | 2029 |  |
State | Research and Development. |  |  |
Income Tax Disclosure [Line Items] |  |  |
Tax credit carryforwards | $ 1,800,000 |  |

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- Definition Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319 + Details
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