Segment Reporting (Capital Expenditures of Reportable Segments) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Total consolidated property and equipment additions	$ 1,251.4	$ 884.4
Assets acquired under capital-related vendor financing arrangements	(743.4)	(614.4)
Assets acquired under capital leases	(29.5)	(31.4)
Changes in current liabilities related to capital expenditures	167.5	261.8
Total consolidated capital expenditures	646.0	500.4
U.K./Ireland [Member]
Segment Reporting Information [Line Items]
Total consolidated property and equipment additions	559.2	409.1
Belgium [Member]
Segment Reporting Information [Line Items]
Total consolidated property and equipment additions	185.2	124.7
Germany [Member]
Segment Reporting Information [Line Items]
Total consolidated property and equipment additions	197.2	144.8
Switzerland/Austria [Member]
Segment Reporting Information [Line Items]
Total consolidated property and equipment additions	84.8	67.2
Central and Eastern Europe [Member]
Segment Reporting Information [Line Items]
Total consolidated property and equipment additions	76.5	72.0
Central and Corporate [Member]
Segment Reporting Information [Line Items]
Total consolidated property and equipment additions	148.5	66.6
VodafoneZiggo JV [Member]
Segment Reporting Information [Line Items]
Property and equipment additions - VodafoneZiggo JV	$ 239.8	$ 227.9