Acquisitions and Dispositions (Classes of Assets and Liabilities) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Liabilities:
Cash and restricted cash contributed to the VMED O2 JV in connection with the U.K. JV Transaction	$ (3,424.0)	$ 0.0
Discontinued Operations
Assets:
Current assets	4,868.3		$ 4,519.8
Property and equipment, net	9,465.1		8,614.0
Goodwill	8,214.7		7,918.5
Other assets, net	3,086.9		3,230.4
Total assets	25,635.0		24,282.7
Liabilities:
Current portion of debt and finance lease obligations	3,220.9		2,699.5
Other accrued and current liabilities	2,242.0		2,207.3
Long-term debt and finance lease obligations	16,905.1		16,724.1
Other long-term liabilities	1,788.2		1,566.3
Total liabilities	$ 24,156.2		$ 23,197.2