Stockholders' Equity - Convertible preferred stock (Details)
$ in Thousands
Jul. 25, 2018
shares
Jul. 09, 2018
Dec. 31, 2019
USD ($)
Convertible preferred stock      
Forward stock split ratio for each common stock   0.100534  
Preferred stock outstanding | $     $ 0
Common stock      
Convertible preferred stock      
Conversion of shares (in shares) | shares 19,157,360