Segment Reporting (Capital Expenditures of Reportable Segments) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Total consolidated property and equipment additions	$ 2,741.7	$ 2,657.9
Assets acquired under capital-related vendor financing arrangements	(1,659.2)	(1,740.2)
Assets acquired under capital leases	(68.1)	(128.4)
Changes in current liabilities related to capital expenditures	128.5	61.4
Third-party payments	1,216.1	1,139.5
Proceeds received for transfers to related parties	(73.2)	(288.8)
Total capital expenditures, net	1,142.9	850.7
U.K./Ireland
Segment Reporting Information [Line Items]
Total consolidated property and equipment additions	1,495.8	1,586.9
Belgium
Segment Reporting Information [Line Items]
Total consolidated property and equipment additions	564.6	468.1
Switzerland
Segment Reporting Information [Line Items]
Total consolidated property and equipment additions	164.9	163.4
Central and Eastern Europe
Segment Reporting Information [Line Items]
Total consolidated property and equipment additions	106.5	166.6
Central and Corporate
Segment Reporting Information [Line Items]
Total consolidated property and equipment additions	409.9	272.9
VodafoneZiggo JV
Segment Reporting Information [Line Items]
Property and equipment additions - VodafoneZiggo JV	$ 691.2	$ 646.5