Segment Reporting (Summary of Impact on the Adjusted OBIDA) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Adjusted OIBDA	$ 0.0	$ 0.0	$ 0.0
Revenue	11,541.5	11,957.9	11,276.4
Operating Segments | U.K./Ireland
Segment Reporting Information [Line Items]
Adjusted OIBDA	(66.6)	(61.7)	(52.8)
Operating Segments | Switzerland
Segment Reporting Information [Line Items]
Adjusted OIBDA	(33.0)	(36.7)	(32.3)
Operating Segments | Central and Eastern Europe
Segment Reporting Information [Line Items]
Adjusted OIBDA	(14.7)	(15.5)	(13.4)
Central and Corporate
Segment Reporting Information [Line Items]
Adjusted OIBDA	$ 114.3	$ 113.9	$ 98.5