Segment Reporting (Capital Expenditures of Reportable Segments) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Total consolidated property and equipment additions	$ 1,900.1	$ 2,040.1
Assets acquired under capital-related vendor financing arrangements	(1,033.6)	(1,303.2)
Assets acquired under finance leases	(31.2)	(47.2)
Changes in current liabilities related to capital expenditures	125.2	210.4
Third-party payments	963.0	976.0
Proceeds received for transfers to related parties	(2.5)	(75.9)
Total capital expenditures, net	960.5	900.1
VodafoneZiggo JV
Segment Reporting Information [Line Items]
Property and equipment additions - VodafoneZiggo JV	685.3	680.4
Operating Segments | U.K./Ireland
Segment Reporting Information [Line Items]
Total consolidated property and equipment additions	1,029.7	1,128.5
Operating Segments | Belgium
Segment Reporting Information [Line Items]
Total consolidated property and equipment additions	375.1	391.6
Operating Segments | Switzerland
Segment Reporting Information [Line Items]
Total consolidated property and equipment additions	181.8	207.2
Operating Segments | Central and Eastern Europe
Segment Reporting Information [Line Items]
Total consolidated property and equipment additions	69.3	66.2
Central and Corporate
Segment Reporting Information [Line Items]
Total consolidated property and equipment additions	$ 244.2	$ 246.6