Segment Reporting (Capital Expenditures of Reportable Segments) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Property and equipment additions	$ 2,880.5	$ 3,705.6	$ 3,703.5
Assets acquired under capital-related vendor financing arrangements	(1,727.0)	(2,175.5)	(2,336.2)
Assets acquired under finance leases	(66.9)	(102.4)	(106.7)
Changes in current liabilities related to capital expenditures	156.5	25.3	(10.6)
Total capital expenditures, net	1,243.1	1,453.0	1,250.0
Third-party payments	1,323.9	1,552.7	1,586.5
Proceeds received for transfers to related parties	(80.8)	(99.7)	(336.5)
VodafoneZiggo JV
Segment Reporting Information [Line Items]
Property and equipment additions - VodafoneZiggo JV	887.9	988.7	933.9
Operating Segments | U.K./Ireland
Segment Reporting Information [Line Items]
Property and equipment additions	1,578.0	1,988.9	2,161.8
Operating Segments | Belgium
Segment Reporting Information [Line Items]
Property and equipment additions	537.2	790.8	691.0
Operating Segments | Switzerland
Segment Reporting Information [Line Items]
Property and equipment additions	277.9	249.6	244.4
Operating Segments | Central and Eastern Europe
Segment Reporting Information [Line Items]
Property and equipment additions	107.0	152.8	158.2
Central and Corporate
Segment Reporting Information [Line Items]
Property and equipment additions	$ 380.4	$ 523.5	$ 448.1