Condensed Statements of Convertible Preferred Stock and Stockholders' (Deficit) Equity (Unaudited) (Parenthetical) $ in Thousands  | 
3 Months Ended | 
|---|---|
| 
 Mar. 31, 2019  
USD ($) 
 | |
| Issuance costs | $ 216 | 
| Convertible Preferred Stock | |
| Issuance costs | $ 1,293 | 
| X | ||||||||||
- Definition The cash outflow for cost incurred directly with the issuance of an equity security. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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| X | ||||||||||
- Details 
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