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Stock Plans and Stock-Based Compensation - 2016 Employee Stock Purchase Plan - Additional Information (Details) - USD ($)
$ in Thousands
3 Months Ended
Sep. 15, 2016
Mar. 31, 2019
Mar. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Shares reserved for issuance   4,140,323  
Stock-based compensation expense   $ 7,785 $ 6,694
2016 Employee Stock Purchase Plan      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Shares reserved for issuance 500,000    
Purchase price as percentage of fair market value of common stock 85.00%    
Shares purchased under the plan   24,266 44,193
Stock-based compensation expense   $ 300 $ 200
2016 Employee Stock Purchase Plan | Maximum      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Increase in number of shares reserved and available for issuance 200,000    
2016 Employee Stock Purchase Plan | Common Stock      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Increase in number of shares reserved and available for issuance, percentage 1.00%    
2016 Employee Stock Purchase Plan | Common Stock | Maximum      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Purchase price, discount percentage 15.00%