Quarterly report pursuant to Section 13 or 15(d)

Basis of Presentation - Additional Information (Details)

v3.10.0.1
Basis of Presentation - Additional Information (Details)
$ / shares in Units, $ in Thousands
3 Months Ended 9 Months Ended 12 Months Ended
Jun. 26, 2018
USD ($)
$ / shares
shares
May 30, 2018
USD ($)
$ / shares
shares
May 15, 2018
$ / shares
Sep. 30, 2018
USD ($)
Sep. 30, 2017
USD ($)
Sep. 30, 2018
USD ($)
Sep. 30, 2017
USD ($)
Dec. 31, 2017
USD ($)
Organization Consolidation And Presentation Of Financial Statements [Line Items]                
Reverse share split     0.0636          
Share consolidation basis nominal value per share | $ / shares     $ 0.01571          
Share consolidation basis renominalisation value per share | $ / shares     $ 0.01          
Net proceeds from issuance of stock after deducting underwriting discounts,commissions and offering cost $ 2,400 $ 71,800       $ 74,155    
Net losses       $ 24,905 $ 8,171 52,799 $ 20,288 $ 29,406
Accumulated deficit       107,536   107,536   54,737
Cash and cash equivalents       39,598   39,598   8,485
Short-term investments       68,509   68,509   $ 30,731
Cash resources available under the secured credit facility       $ 15,000   $ 15,000    
IPO                
Organization Consolidation And Presentation Of Financial Statements [Line Items]                
Number of shares issued | shares 200,000 6,150,000            
Offering price per share | $ / shares $ 13.00 $ 13.00