XML 48 R34.htm IDEA: XBRL DOCUMENT v3.19.3
Stock-Based Compensation - Additional Information (Details) - USD ($)
$ / shares in Units, $ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Dec. 31, 2018
Mar. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Stock options, grants in period, shares 300,846 130,000 3,388,496 1,526,989    
Stock options, grants in period, weighted average grant date fair value per share $ 5.49 $ 9.10 $ 6.53 $ 7.45    
Stock options, exercised 1,052 0 18,770 713,931    
2018 Equity Incentive Plan            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Number of shares issued or transferred           3,570,000
2015 Stock Plan            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Shares not vested and subject to repurchase 552,364   552,364   927,123  
Cash received from early exercise of unvested options $ 2.0   $ 2.0   $ 2.8  
Award vesting period     48 months