Segment Reporting (Geographic Segments) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Revenue	$ 4,156.1	$ 3,519.0
VodafoneZiggo JV [Member]
Segment Reporting Information [Line Items]
Revenue	1,195.0	1,083.8
Operating Segments [Member] \| U.K. [Member]
Segment Reporting Information [Line Items]
Revenue	1,644.4	1,400.4
Operating Segments [Member] \| Germany [Member]
Segment Reporting Information [Line Items]
Revenue	782.8	629.1
Operating Segments [Member] \| Belgium [Member]
Segment Reporting Information [Line Items]
Revenue	759.6	661.4
Operating Segments [Member] \| Switzerland [Member]
Segment Reporting Information [Line Items]
Revenue	344.9	331.2
Operating Segments [Member] \| Ireland [Member]
Segment Reporting Information [Line Items]
Revenue	133.8	104.0
Operating Segments [Member] \| Poland [Member]
Segment Reporting Information [Line Items]
Revenue	116.0	95.9
Operating Segments [Member] \| Austria [Member]
Segment Reporting Information [Line Items]
Revenue	109.7	92.5
Operating Segments [Member] \| Hungary [Member]
Segment Reporting Information [Line Items]
Revenue	85.1	71.9
Operating Segments [Member] \| The Czech Republic [Member]
Segment Reporting Information [Line Items]
Revenue	60.4	44.9
Operating Segments [Member] \| Romania [Member]
Segment Reporting Information [Line Items]
Revenue	50.3	42.0
Operating Segments [Member] \| Slovakia [Member]
Segment Reporting Information [Line Items]
Revenue	16.5	14.3
Other, including intersegment eliminations
Segment Reporting Information [Line Items]
Revenue	$ 52.6	$ 31.4

The amount of revenue from sale of goods and services reduced by sales returns, allowances, and discounts reported by an equity method investment of the entity.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721683-107760

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=66011266&loc=d3e33918-111571

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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