Description of Business and Basis of Presentation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	Apr. 09, 2019	Apr. 02, 2019	Mar. 31, 2019	Dec. 31, 2018
Description Of Business And Basis Of Presentation [Line Items]
Common stock shares authorized			340,000,000	340,000,000
Common stock shares outstanding			35,831,684	22,438,472
Subsequent Event
Description Of Business And Basis Of Presentation [Line Items]
Preferred stock shares authorized		1,000,000,000
Subsequent Event | Co-founders
Description Of Business And Basis Of Presentation [Line Items]
Shares of common stock exchanged		12,779,709
Class A Common Stock
Description Of Business And Basis Of Presentation [Line Items]
Offering costs			$ 7.7
Class A Common Stock | Subsequent Event
Description Of Business And Basis Of Presentation [Line Items]
Number of shares issued		35,496,845
Underwriting discounts and commissions		$ 70.3
Common stock shares authorized		18,000,000,000
Common stock shares outstanding		255,007,393
Redeemable Convertible Preferred Stock | Subsequent Event
Description Of Business And Basis Of Presentation [Line Items]
Conversion of stock, shares converted		219,175,709
Class B Common Stock | Subsequent Event
Description Of Business And Basis Of Presentation [Line Items]
Common stock shares authorized		100,000,000
Common stock shares outstanding		12,779,709
IPO | Class A Common Stock | Subsequent Event
Description Of Business And Basis Of Presentation [Line Items]
Number of shares issued		32,500,000
Price per share		$ 72.00
Proceeds from issuance of common stock in initial public offering, net of issuance costs		$ 2,500.0
Exercise by Underwriters' Option to Purchase Additional Shares | Class A Common Stock | Subsequent Event
Description Of Business And Basis Of Presentation [Line Items]
Number of shares issued	2,996,845
Price per share	$ 72.00