Segment Reporting (Revenue by Major Category) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Principal Transaction Revenue [Line Items]
Total	$ 1,172.0	$ 1,269.1	$ 2,446.6	$ 2,440.3
Total residential fixed revenue
Principal Transaction Revenue [Line Items]
Total	423.5	443.8	872.2	855.7
Total subscription revenue
Principal Transaction Revenue [Line Items]
Total	415.5	439.2	856.1	846.0
Broadband internet
Principal Transaction Revenue [Line Items]
Total	248.5	238.3	496.9	456.7
Video
Principal Transaction Revenue [Line Items]
Total	131.8	153.7	279.1	297.8
Fixed-line telephony
Principal Transaction Revenue [Line Items]
Total	35.2	47.2	80.1	91.5
Non-subscription revenue
Principal Transaction Revenue [Line Items]
Total	8.0	4.6	16.1	9.7
Total residential revenue
Principal Transaction Revenue [Line Items]
Total	588.7	606.4	1,208.9	1,170.2
Total residential mobile revenue
Principal Transaction Revenue [Line Items]
Total	165.2	162.6	336.7	314.5
Subscription revenue
Principal Transaction Revenue [Line Items]
Total	130.6	125.0	259.1	240.7
Non-subscription revenue
Principal Transaction Revenue [Line Items]
Total	34.6	37.6	77.6	73.8
Total B2B revenue
Principal Transaction Revenue [Line Items]
Total	232.0	225.9	464.8	432.9
Subscription revenue
Principal Transaction Revenue [Line Items]
Total	113.5	112.5	227.4	216.3
Non-subscription revenue
Principal Transaction Revenue [Line Items]
Total	118.5	113.4	237.4	216.6
Other revenue
Principal Transaction Revenue [Line Items]
Total	$ 351.3	$ 436.8	$ 772.9	$ 837.2