Segment Reporting (Geographic Segments) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2024	Mar. 31, 2023
Segment Reporting Information [Line Items]
Revenue	$ 1,945.1	$ 1,868.4
VMO2 JV
Segment Reporting Information [Line Items]
Revenue	3,282.8	3,162.7
VodafoneZiggo JV
Segment Reporting Information [Line Items]
Revenue	1,114.0	1,083.4
Operating Segments \| Switzerland
Segment Reporting Information [Line Items]
Revenue	854.0	807.4
Operating Segments \| Belgium
Segment Reporting Information [Line Items]
Revenue	720.0	716.6
Operating Segments \| Ireland
Segment Reporting Information [Line Items]
Revenue	123.0	123.0
Operating Segments \| Slovakia
Segment Reporting Information [Line Items]
Revenue	12.7	13.3
Other, including intersegment eliminations
Segment Reporting Information [Line Items]
Revenue	$ 235.4	$ 208.1

Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

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