Segment Reporting (Summary of Impact on the Adjusted OBIDA) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Increase (decrease) in adjusted OIBDA	$ 0.0	$ 0.0	$ 0.0	$ 0.0
Operating Segments | U.K./Ireland
Segment Reporting Information [Line Items]
Increase (decrease) in adjusted OIBDA	(13.3)	(16.2)	(37.7)	(48.0)
Operating Segments | Switzerland
Segment Reporting Information [Line Items]
Increase (decrease) in adjusted OIBDA	(5.2)	(7.8)	(14.8)	(24.5)
Operating Segments | Central and Eastern Europe
Segment Reporting Information [Line Items]
Increase (decrease) in adjusted OIBDA	(2.6)	(3.6)	(7.8)	(10.9)
Central and Corporate
Segment Reporting Information [Line Items]
Increase (decrease) in adjusted OIBDA	$ 21.1	$ 27.6	$ 60.3	$ 83.4