Segment Reporting (Capital Expenditures of Reportable Segments) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Total property and equipment additions	$ 3,705.6	$ 3,703.5	$ 3,733.8
Assets acquired under capital-related vendor financing arrangements	(2,175.5)	(2,336.2)	(1,811.2)
Assets acquired under capital leases	(102.4)	(106.7)	(100.4)
Changes in current liabilities related to capital expenditures	25.3	(10.6)	(282.3)
Total capital expenditures, net	1,453.0	1,250.0	1,539.9
Third-party payments	1,552.7	1,586.5	1,738.2
Proceeds received for transfers to related parties	(99.7)	(336.5)	(198.3)
VodafoneZiggo JV
Segment Reporting Information [Line Items]
Property and equipment additions - VodafoneZiggo JV	988.7	933.9	0.0
U.K./Ireland
Segment Reporting Information [Line Items]
Total property and equipment additions	1,988.9	2,161.8	1,761.1
Belgium
Segment Reporting Information [Line Items]
Total property and equipment additions	790.8	691.0	588.4
Switzerland
Segment Reporting Information [Line Items]
Total property and equipment additions	249.6	244.4	260.4
Central and Eastern Europe
Segment Reporting Information [Line Items]
Total property and equipment additions	152.8	158.2	128.6
The Netherlands
Segment Reporting Information [Line Items]
Total property and equipment additions	0.0	0.0	588.9
Central and Corporate
Segment Reporting Information [Line Items]
Total property and equipment additions	$ 523.5	$ 448.1	$ 406.4