Income Taxes - Schedule of Components of Income (Loss) before Provision for Income Taxes (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Domestic	$ 2.0	$ (0.4)	$ 23.5
Foreign	(1.9)	(10.9)	(2.1)
Income (loss) before provision for income taxes	$ 0.1	$ (11.3)	$ 21.4