v3.19.3
Investments and Fair Value Measurement - Narrative (Details)
$ / shares in Units, $ in Millions
1 Months Ended 3 Months Ended
May 14, 2019
shares
Feb. 29, 2016
warrant
$ / shares
shares
Mar. 31, 2019
USD ($)
Sep. 30, 2018
USD ($)
Mar. 31, 2018
USD ($)
Sep. 30, 2019
Dec. 31, 2018
USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]              
Number of warrants issued | warrant   2          
Exercise price of warrants (in dollars per share) | $ / shares   $ 0.01          
Warrants | $             $ 45
Exercise of common stock warrants | $       $ 0 $ 1    
Redeemable Non-Controlling Interest | Redeemable Convertible Preferred Stock              
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]              
Exercise of common stock warrants | $     $ 45        
Warrants Issued, Tranche One              
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]              
Number of securities called by warrants (in shares) | shares   205,034          
Warrants Issued, Tranche Two              
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]              
Number of securities called by warrants (in shares) | shares   820,138          
IPO | Holders of 2021 Convertible Notes and 2022 Convertible Notes              
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]              
Conversion of Convertible Notes to common stock in connection with initial public offering (in shares) | shares 94,000,000            
Qualified Input Public Offering Rate              
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]              
Convertible debt embedded derivative, rate           1