Income Taxes - Income Before Income Tax (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Domestic	$ 934.3	$ 854.1	$ 762.3
Foreign	68.0	95.6	78.2
Income before income taxes	$ 1,002.3	$ 949.7	$ 840.5