v3.19.2
Stockholders' Equity - Additional Information (Details)
shares in Millions, $ in Millions
6 Months Ended 12 Months Ended
Jun. 30, 2019
USD ($)
Plan
shares
Jun. 30, 2018
USD ($)
Dec. 31, 2018
shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Number of share-based employee compensation plans | Plan 3    
RSAs      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Fair value of vested shares $ 16.7 $ 6.3  
Pre-2017 RSUs      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Unrecognized compensation cost $ 94.6    
Weighted average recognition period 1 year 2 months 12 days    
Post-2017 RSUs      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Unrecognized compensation cost $ 1,300.0    
Weighted average recognition period 3 years    
Service condition satisfied, years 4 years    
Post-2017 RSUs | First Year      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting percentage 10.00%    
Post-2017 RSUs | Second Year      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting percentage 20.00%    
Post-2017 RSUs | Third Year      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting percentage 30.00%    
Post-2017 RSUs | Fourth Year      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting percentage 40.00%    
RSUs      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
RSUs vested but not yet settled | shares 17.8   22.4
Stock Options      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Weighted average recognition period 2 years 1 month 6 days    
Unrecognized compensation cost related to stock options $ 27.7