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Equity Financings and Warrants (Details Textual) - USD ($) $ / shares in Units, $ in Thousands |  | 12 Months Ended |  |  |
--- | --- | --- | --- | --- | ---
Jun. 03, 2020 | Dec. 31, 2021 | Dec. 31, 2020 | Jul. 22, 2020 | Jul. 14, 2020 | Jan. 11, 2017
Equity Financing And Warrants [Line Items] |  |  |  |  |  |
Net proceeds from issuance of common stock |  | $ 24,070 | $ 50,894 |  |  |
Common stock, par value |  | $ 0.001 | $ 0.001 |  |  |
Common stock, shares issued |  | 14,410,143 | 9,548,150 |  |  |
JonesTrading |  |  |  |  |  |
Equity Financing And Warrants [Line Items] |  |  |  |  |  |
Percentage of selling commission per additional shares sold |  |  |  |  |  | 3.00%
Sales Agreement |  |  |  |  |  |
Equity Financing And Warrants [Line Items] |  |  |  |  |  |
Common stock, shares issued |  |  | 2,214,301 |  |  |
Net proceeds from issuance of common stock |  |  | $ 14,400 |  |  |
Sales Agreement | JonesTrading |  |  |  |  |  |
Equity Financing And Warrants [Line Items] |  |  |  |  |  |
Common stock, par value |  |  |  |  |  | $ 0.001
Aggregate offering price of common stock authorized |  |  |  |  | $ 32,400 | $ 7,300
2020 Sales Agreement |  |  |  |  |  |
Equity Financing And Warrants [Line Items] |  |  |  |  |  |
Net proceeds from issuance of common stock |  | $ 23,300 | $ 28,900 |  |  |
Aggregate offering price of common stock authorized |  |  |  | $ 54,000 |  |
Sale of common stock |  | 4,861,993 | 5,066,279 |  |  |
Direct Offering |  |  |  |  |  |
Equity Financing And Warrants [Line Items] |  |  |  |  |  |
Common stock issued | 348,000 |  |  |  |  |
Purchase price per share | $ 9.00 |  |  |  |  |
Pre-funded warrants to purchase shares of common stock | 325,500 |  |  |  |  |
Purchase price per warrant | $ 8.999 |  |  |  |  |
Pre-funded warrants outstanding |  |  | 0 |  |  |
Net proceeds from issuance of common stock | $ 5,300 |  |  |  |  |
Percentage of selling commission per additional shares sold | 8.00% |  |  |  |  |

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