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Subsequent Events - Additional Information (Detail) - Subsequent Event [Member] - Hercules Capital, Inc. [Member] - Loan and Security Agreement [Member] - Term Loan Facility [Member] - USD ($)
Oct. 29, 2019
Oct. 31, 2019
Subsequent Event [Line Items]    
Credit facility, aggregate principal amount   $ 50,000,000
First Tranche [Member]    
Subsequent Event [Line Items]    
Gross proceeds from debt $ 25,000,000  
Proceeds from debt 24,575,000  
Payment of closing costs $ 425,000  
Second Tranche Available Through March 15, 2021 [Member]    
Subsequent Event [Line Items]    
Credit facility, aggregate principal amount   12,500,000
Third Tranche Available Upon Approval on or Prior to June 30, 2021 [Member]    
Subsequent Event [Line Items]    
Credit facility, aggregate principal amount   $ 12,500,000