v3.19.3
Organization and Basis of Presentation - Additional Information (Details)
 1 Months Ended 3 Months Ended 9 Months Ended 12 Months Ended
Aug. 15, 2018
Jul. 16, 2018
Aug. 31, 2018
USD ($)
$ / shares
shares
Mar. 31, 2019
shares
Sep. 30, 2018
USD ($)
shares
Sep. 30, 2019
USD ($)
Sep. 30, 2018
USD ($)
Dec. 31, 2018
USD ($)
Organization And Basis Of Presentation [Line Items]                
Number of securities called by each warrant or right | shares     1          
Conversion of preferred stock warrants into common stock warrants         $ 84,676      
Outstanding convertible promissory notes and accrued interest converted, amount           $ 0 $ 14,898,326  
Conversion ratio 0.5 0.0467            
Accumulated deficit           (94,676,903)   $ (72,762,428)
Net cash used in operating activities           (20,045,188) $ (15,853,679) 19,900,000
Cash and cash equivalents           $ 8,224,801   $ 16,522,729
Common Stock                
Organization And Basis Of Presentation [Line Items]                
Number of units sold (shares) | shares       748,427 3,864,000      
Number of securities called by each IPO unit | shares     1          
Common warrants                
Organization And Basis Of Presentation [Line Items]                
Number of securities called by each IPO unit | shares     1          
Initial Public Offering                
Organization And Basis Of Presentation [Line Items]                
Number of units sold (shares) | shares     3,864,000          
Offering price per unit | $ / shares     $ 6.125          
Net cash proceeds after deducting underwriting discounts and commissions     $ 19,400,000          
Underwriters' discounts and commissions     2,200,000          
Offering expenses     $ 2,100,000          
Number of common stock issuable upon conversion of convertible preferred stock (shares) | shares     2,850,280          
Conversion of preferred stock warrants into common stock warrants     $ 84,676          
Fair value of warrants     $ 400,000          
Percentage of offering price per unit     100.00%          
Initial Public Offering | Common Stock                
Organization And Basis Of Presentation [Line Items]                
Outstanding convertible promissory notes and accrued interest converted, amount     $ 14,900,000          
Outstanding convertible promissory notes and accrued interest converted, shares | shares     3,239,294   2,850,280      
Initial Public Offering | Maximum                
Organization And Basis Of Presentation [Line Items]                
Issuance of warrants to underwriters to purchase of common stock | shares     115,920          
Underwriters Over-Allotment Option                
Organization And Basis Of Presentation [Line Items]                
Number of units sold (shares) | shares     504,000