Income Taxes (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Mar. 31, 2021	Sep. 30, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Unrecognized tax benefits		$ 6.3	$ 12.2
Income tax interest and penalty expense	$ 9.2	6.3
Accrued interest related to uncertain tax positions		$ 2.6	$ 3.3