Stockholders’ Equity - October 2019 and April 2020 Follow-On Offering (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
	Apr. 08, 2019	Jun. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Class A Common Stock | October 2019 Follow-On Offering
Class of Stock [Line Items]
Issuance of common stock from equity incentive plans (in shares)			19,881,059
Public offering price (in dollars per share)			$ 42.00
Net proceeds			$ 810.0
Stock surrendered (in shares)			45,393
Class A Common Stock | April 2020 Follow-On Offering
Class of Stock [Line Items]
Issuance of common stock from equity incentive plans (in shares)		12,835,245
Public offering price (in dollars per share)		$ 50.25
Net proceeds		$ 626.3
Stock surrendered (in shares)		596,418
Class A Common Stock | Underwriter
Class of Stock [Line Items]
Issuance of common stock from equity incentive plans (in shares)	6,000,000
Shares issued to underwriters (in shares)		1,674,162	2,593,181
LLC units | October 2019 Follow-On Offering
Class of Stock [Line Items]
Stock surrendered (in shares)				19,835,666
LLC units | April 2020 Follow-On Offering
Class of Stock [Line Items]
Stock surrendered (in shares)		12,238,827