Segment Reporting (Revenue by Major Category) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Principal Transaction Revenue [Line Items]
Revenue	$ 1,920.8	$ 1,901.4	$ 2,989.2	$ 3,499.9	$ 3,311.7	$ 2,845.4	$ 2,619.2	$ 2,769.1	$ 10,311.3	$ 11,545.4	$ 11,115.8
Total residential fixed revenue
Principal Transaction Revenue [Line Items]
Revenue									5,205.8	7,173.6	7,149.6
Total subscription revenue
Principal Transaction Revenue [Line Items]
Revenue									5,044.6	6,956.3	6,955.1
Broadband internet
Principal Transaction Revenue [Line Items]
Revenue									2,371.7	3,181.9	3,098.2
Video
Principal Transaction Revenue [Line Items]
Revenue									1,831.8	2,446.2	2,460.3
Fixed-line telephony
Principal Transaction Revenue [Line Items]
Revenue									841.1	1,328.2	1,396.6
Non-subscription revenue
Principal Transaction Revenue [Line Items]
Revenue									161.2	217.3	194.5
Total residential revenue
Principal Transaction Revenue [Line Items]
Revenue									7,597.3	8,955.4	8,769.6
Total residential mobile revenue
Principal Transaction Revenue [Line Items]
Revenue									2,391.5	1,781.8	1,620.0
Subscription revenue
Principal Transaction Revenue [Line Items]
Revenue									1,630.7	1,090.3	931.9
Non-subscription revenue
Principal Transaction Revenue [Line Items]
Revenue									760.8	691.5	688.1
Total B2B revenue
Principal Transaction Revenue [Line Items]
Revenue									1,862.8	1,995.4	1,861.5
Subscription revenue
Principal Transaction Revenue [Line Items]
Revenue									619.0	563.9	476.7
Non-subscription revenue
Principal Transaction Revenue [Line Items]
Revenue									1,243.8	1,431.5	1,384.8
Other revenue
Principal Transaction Revenue [Line Items]
Revenue									$ 851.2	$ 594.6	$ 484.7