Taxation (Income Before Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
U.S.	$ 845.8	$ 511.1	$ 491.8
Foreign	223.3	461.8	646.3
Income before income taxes	$ 1,069.1	$ 972.9	$ 1,138.1