Segment Reporting (Revenue by Major Category) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Principal Transaction Revenue [Line Items]
Total	$ 1,920.6	$ 1,207.1	$ 4,367.2	$ 3,647.4
Total residential fixed revenue
Principal Transaction Revenue [Line Items]
Total	785.2	457.1	1,657.4	1,312.8
Total subscription revenue
Principal Transaction Revenue [Line Items]
Total	772.9	448.8	1,629.0	1,294.8
Broadband internet
Principal Transaction Revenue [Line Items]
Total	390.7	247.2	887.6	703.9
Video
Principal Transaction Revenue [Line Items]
Total	326.9	153.8	606.0	451.6
Fixed-line telephony
Principal Transaction Revenue [Line Items]
Total	55.3	47.8	135.4	139.3
Non-subscription revenue
Principal Transaction Revenue [Line Items]
Total	12.3	8.3	28.4	18.0
Total residential revenue
Principal Transaction Revenue [Line Items]
Total	1,144.1	624.4	2,353.0	1,794.6
Total residential mobile revenue
Principal Transaction Revenue [Line Items]
Total	358.9	167.3	695.6	481.8
Subscription revenue
Principal Transaction Revenue [Line Items]
Total	272.4	131.0	531.5	371.7
Non-subscription revenue
Principal Transaction Revenue [Line Items]
Total	86.5	36.3	164.1	110.1
Total B2B revenue
Principal Transaction Revenue [Line Items]
Total	441.0	233.3	905.8	666.2
Subscription revenue
Principal Transaction Revenue [Line Items]
Total	224.3	116.7	451.7	333.0
Non-subscription revenue
Principal Transaction Revenue [Line Items]
Total	216.7	116.6	454.1	333.2
Other revenue
Principal Transaction Revenue [Line Items]
Total	$ 335.5	$ 349.4	$ 1,108.4	$ 1,186.6