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Income Tax Matters - Additional Information (Details) - USD ($) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Tax Credit Carryforward [Line Items] |  |  |  |
Net operating loss | $ 94,600,000 |  |  |
Operating loss expiration period | Dec. 31, 2030 |  |  |
Increase (decrease) in valuation allowance | $ (3,500,000) | $ 1,500,000 | $ (4,600,000) |
Unrecognized tax benefits | 3,800,000 | 4,100,000 | 1,500,000 | $ 1,500,000
Amount that would be reflected in income tax provision if unrecognized tax benefits are recognized | 1,500,000 |  |  |
Accrued interest and penalties on unrecognized tax benefits | 300,000 | 300,000 |  |
Accrued interest and penalties on unrecognized tax benefits, current | 0 | 0 |  |
(Decrease) increase in interest and penalty |  | $ 100,000 | $ 100,000 |
Research Tax Credit Carryforward |  |  |  |
Tax Credit Carryforward [Line Items] |  |  |  |
Tax credit carryforward | $ 8,100,000 |  |  |
Tax credit carryforward expiration period | Dec. 31, 2040 |  |  |

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- Definition The amount the liability recorded for the income tax examination increased or decreased in the current year/accounting period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -URI http://asc.fasb.org/extlink&oid=84230637&loc=SL6600010-109319 + Details
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