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Summary of Warrant Activity (Parenthetical) (Detail) - shares
1 Months Ended 12 Months Ended
Nov. 30, 2018
Dec. 31, 2019
Dec. 31, 2018
Class Of Warrant Or Right [Line Items]      
Number of shares of warrants forfeited/cancelled   2,337 6,095
Healthcare Ventures VIII      
Class Of Warrant Or Right [Line Items]      
Number of shares of warrants forfeited/cancelled 1,845