Segment Reporting (Geographic Segments) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Revenue	$ 1,901.4	$ 2,845.4	$ 8,390.5	$ 8,233.7
Operating Segments | U.K.
Segment Reporting Information [Line Items]
Revenue	0.0	1,543.6	2,736.4	4,457.3
Operating Segments | Belgium
Segment Reporting Information [Line Items]
Revenue	755.4	746.6	2,302.9	2,147.2
Operating Segments | Switzerland
Segment Reporting Information [Line Items]
Revenue	830.2	315.0	2,497.4	930.9
Operating Segments | Ireland
Segment Reporting Information [Line Items]
Revenue	136.0	126.4	406.2	366.2
Operating Segments | Slovakia
Segment Reporting Information [Line Items]
Revenue	12.9	12.6	39.1	37.5
Other, including intersegment eliminations
Segment Reporting Information [Line Items]
Revenue	$ 166.9	$ 101.2	$ 408.5	$ 294.6