v3.19.3.a.u2
Redeemable Convertible Preferred Stock, Common Stock, and Equity (Deficit) - SAR and Option Activity (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Millions
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Share-Based Compensation Arrangement By Share-Based Payment Award, Options And Equity Instruments Other Than Options, Nonvested, Number Of Shares [Abstract]    
Weighted-Average Exercise Price Per Share, Outstanding (in dollars per share) $ 9.22  
Weighted-Average Exercise Price Per Share, Awards granted (in dollars per share) 43.00  
Weighted-Average Exercise Price Per Share, Awards exercised (in dollars per share) 2.85  
Weighted-Average Exercise Price Per Share, Awards canceled and forfeited (in dollars per share) 33.29  
Weighted-Average Exercise Price Per Share, Awards expired (in dollars per share) 26.49  
Weighted-Average Exercise Price Per Share, Outstanding (in dollars per share) 9.79 $ 9.22
Weighted-Average Exercise Price Per Share, Vested and expected to vest (in dollars per share) 4.97  
Weighted-Average Exercise Price Per Share, Exercisable (in dollars per share) $ 4.97  
Share-Based Compensation Arrangement By Share-based Payment Award, Options And Equity Instruments Other Than Options, Nonvested, Additional Disclosures [Abstract]    
Weighted-Average Contractual Life, Outstanding 4 years 9 months 5 years 8 months 26 days
Weighted-Average Contractual Life, Vested and expected to vest 4 years 5 months 26 days  
Weighted-Average Contractual Life, Exercisable 4 years 5 months 26 days  
Aggregate Intrinsic Value, Outstanding $ 746 $ 1,456
Aggregate Intrinsic Value, Vested and expected to vest 745  
Aggregate Intrinsic Value, Exercisable $ 745  
SARs    
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]    
Awards, outstanding (in shares) 758  
Awards granted (in shares) 86  
Awards exercised (in shares) (417)  
Awards canceled and forfeited (in shares) (36)  
Awards expired (in shares) (54)  
Awards, outstanding (in shares) 337 758
Vested and expected to vest (in shares) 203  
Exercisable (in shares) 203  
Stock options    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]    
Options outstanding (in shares) 42,936  
Awards granted (in shares) 250  
Awards exercised (in shares) (6,884)  
Awards canceled and forfeited (in shares) (1,462)  
Awards expired (in shares) (39)  
Options outstanding (in shares) 34,801 42,936
Vested and expected to vest (in shares) 29,585  
Exercisable (in shares) 29,585