Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Accounts receivable, related party	$ 0.2	$ 0.0
Current portion of deferred revenue, related party	34.2	0.0
Deferred revenue, net of current portion, related party	$ 28.5	$ 0.0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	74,342,178	66,234,056
Common stock, shares outstanding	74,342,178	66,234,056