Segment Reporting (Performance Measures) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Segment Reporting [Line Items]
Total consolidated revenue	$ 1,172.0	$ 1,269.1	$ 2,446.6	$ 2,440.3
VMO2 JV And VodafoneZiggo JV
Segment Reporting [Line Items]
Total consolidated revenue	(4,354.0)	(4,496.8)	(8,724.9)	(8,675.1)
Operating Segments
Segment Reporting [Line Items]
Total consolidated revenue	5,227.8	5,420.5	10,502.1	10,474.3
Operating Segments \| VMO2 JV (nonconsolidated)
Segment Reporting [Line Items]
Total consolidated revenue	3,220.3	3,373.5	6,442.7	6,499.8
Operating Segments \| VodafoneZiggo JV (nonconsolidated)
Segment Reporting [Line Items]
Total consolidated revenue	1,133.7	1,123.3	2,282.2	2,175.3
Operating Segments \| Telenet
Segment Reporting [Line Items]
Total consolidated revenue	716.9	770.2	1,459.5	1,501.7
Operating Segments \| Wyre
Segment Reporting [Line Items]
Total consolidated revenue	34.5	30.7	68.3	58.9
Operating Segments \| VM Ireland
Segment Reporting [Line Items]
Total consolidated revenue	122.4	122.8	249.4	238.6
Intersegment
Segment Reporting [Line Items]
Total consolidated revenue	199.5	179.2	381.4	343.5
Intersegment \| Telenet
Segment Reporting [Line Items]
Total consolidated revenue	36.2	14.9	53.0	26.6
Intersegment \| Wyre
Segment Reporting [Line Items]
Total consolidated revenue	163.3	164.3	328.4	316.9
Total reportable segment revenue
Segment Reporting [Line Items]
Total consolidated revenue	5,427.3	5,599.7	10,883.5	10,817.8
Total reportable segment revenue \| VMO2 JV (nonconsolidated)
Segment Reporting [Line Items]
Total consolidated revenue	3,220.3	3,373.5	6,442.7	6,499.8
Total reportable segment revenue \| VodafoneZiggo JV (nonconsolidated)
Segment Reporting [Line Items]
Total consolidated revenue	1,133.7	1,123.3	2,282.2	2,175.3
Total reportable segment revenue \| Telenet
Segment Reporting [Line Items]
Total consolidated revenue	753.1	785.1	1,512.5	1,528.3
Total reportable segment revenue \| Wyre
Segment Reporting [Line Items]
Total consolidated revenue	197.8	195.0	396.7	375.8
Total reportable segment revenue \| VM Ireland
Segment Reporting [Line Items]
Total consolidated revenue	122.4	122.8	249.4	238.6
Central and other
Segment Reporting [Line Items]
Total consolidated revenue	343.5	387.5	760.3	722.2
Elimination of intercompany
Segment Reporting [Line Items]
Total consolidated revenue	$ (244.8)	$ (221.3)	$ (472.3)	$ (424.6)