Description of Business and Summary of Significant Accounting Policies - Initial Public Offering (Details) - Subsequent event - USD ($) $ / shares in Units, $ in Millions	Apr. 29, 2019	Apr. 23, 2019	Apr. 22, 2019
Class A common stock | IPO
Subsidiary, Sale of Stock [Line Items]
Shares sold (in shares)		75,000,000
Share price (in dollars per share)		$ 19
Net proceeds		$ 1,368.0
Estimated offering costs		8.7
Class A common stock | Over-Allotment Option
Subsidiary, Sale of Stock [Line Items]
Shares sold (in shares)	11,250,000
Share price (in dollars per share)	$ 19.00
Net proceeds	$ 205.2
Class A common stock | Other assets | IPO
Subsidiary, Sale of Stock [Line Items]
Offering costs		$ 5.6
Redeemable Convertible Preferred Stock And Redeemable Convertible Preferred Stock Warrants Converted | Class B common stock
Subsidiary, Sale of Stock [Line Items]
Shares converted (in shares)			1
Shares issued in conversion (in shares)			308,621,636
Common Stock Reclassified Into Class B Common Stock | Class B common stock
Subsidiary, Sale of Stock [Line Items]
Shares converted (in shares)			1
Shares issued in conversion (in shares)			456,213,756