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Stock-Based Compensation - Summary of ESPP Share Activity (Detail) - shares
3 Months Ended 9 Months Ended
Sep. 30, 2020
Jun. 30, 2020
Mar. 31, 2020
Sep. 30, 2019
Jun. 30, 2019
Mar. 31, 2019
Sep. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]              
Purchases (31,705) (31,114) (58,734) (26,726) (31,455) (44,161)  
Available for future purchases, September 30, 2020 2,443,063           2,443,063
2019 Employee Stock Purchase Plan [Member]              
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]              
Additional shares reserved             86,093
Employee Stock Purchase Plan [Member]              
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]              
Available for future purchases, January 1, 2020     438,434       438,434
Purchases             (121,553)
Available for future purchases, September 30, 2020 402,974           402,974
Employee Stock Purchase Plan [Member] | 2019 Employee Stock Purchase Plan [Member]              
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]              
Additional shares reserved             86,093