Components of Income Before Income Taxes (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Domestic	$ 1,122.9	$ 2,201.1	$ 1,775.2
Foreign	535.0	898.1	1,035.0
Income before income taxes	$ 1,657.9	$ 3,099.2	$ 2,810.2