Net Loss per Share - Schedule of Computations of Basic and Diluted Net Loss per Share (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021
Numerator:
Net loss	$ (19.8)	$ (27.4)	$ (25.8)	$ (19.2)	$ (47.2)	$ (45.0)
Denominator:
Weighted-average shares outstanding - basic	152,752,369		149,293,833		152,439,996	149,006,538
Weighted-average shares outstanding - diluted	152,752,369		149,293,833		152,439,996	149,006,538
Net loss per share - basic	$ (0.13)		$ (0.17)		$ (0.31)	$ (0.30)
Net loss per share - diluted	$ (0.13)		$ (0.17)		$ (0.31)	$ (0.30)