Net Income (Loss) per Share - Schedule of Computations of Basic and Diluted Net Income (Loss) per Share (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Numerator:
Net (loss) income	$ (19.2)	$ 8.6
Denominator:
Weighted-average shares outstanding - basic	148,716,050	144,645,325
Effect of dilutive equity instruments		6,533,173
Weighted-average shares outstanding - diluted	148,716,050	151,178,498
Net (loss) income per share - basic	$ (0.13)	$ 0.06
Net (loss) income per share - diluted	$ (0.13)	$ 0.06