Acquisitions and Dispositions (Identifiable Assets and Liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Jun. 01, 2021	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Current assets	$ 5,961.5		$ 5,802.4
Property and equipment, net	6,984.6		7,626.6
Goodwill	9,410.5		9,965.7
Intangible assets subject to amortization, net (note 8)	2,410.0		2,879.9
Other assets, net	2,529.0		3,180.9
Current maturities of debt and finance lease obligations	(986.5)		(1,086.1)
Long-term operating lease liabilities (note 10)	(14,097.3)		(13,861.3)
Other long-term liabilities	(1,955.8)		$ (2,969.3)
Total preliminary fair value of the net assets of the VMED O2 JV	$ 1,478.8
VMED O2 JV
Schedule of Equity Method Investments [Line Items]
Current assets		$ 4,753.6
Property and equipment, net		12,496.0
Goodwill		29,173.4
Intangible assets subject to amortization, net (note 8)		13,274.4
Other assets, net		7,480.1
Current maturities of debt and finance lease obligations		(4,352.5)
Other accrued and current liabilities		(6,055.0)
Long-term operating lease liabilities (note 10)		(21,959.1)
Other long-term liabilities		(5,469.3)
Total preliminary fair value of the net assets of the VMED O2 JV		$ 29,341.6