Acquisitions and Dispositions (Classes of Assets and Liabilities) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Assets:
Current assets	$ 907.7		$ 980.1
Liabilities:
Cash and restricted cash contributed to the VMED O2 JV in connection with the U.K. JV Transaction	(3,424.0)	$ 0.0
Net assets	1,478.8
Disposed of by sale
Assets:
Current assets			4,519.8
Property and equipment, net			8,614.0
Goodwill			7,918.5
Other assets, net			3,230.4
Total assets			24,282.7
Liabilities:
Current portion of debt and finance lease obligations			2,699.5
Other accrued and current liabilities			2,207.3
Long-term debt and finance lease obligations			16,724.1
Other long-term liabilities			1,566.3
Total liabilities			23,197.2
Disposed of by sale | UPC Poland
Assets:
Current assets	23.8		26.8
Property and equipment, net	383.9		427.5
Goodwill	469.9		501.0
Other assets, net	30.1		24.8
Total assets	907.7		980.1
Liabilities:
Current portion of debt and finance lease obligations	38.2		44.3
Other accrued and current liabilities	92.2		99.1
Long-term debt and finance lease obligations	5.4		6.0
Other long-term liabilities	55.5		38.1
Total liabilities	191.3		$ 187.5
Held for sale
Assets:
Current assets	4,868.3
Property and equipment, net	9,465.1
Goodwill	8,214.7
Other assets, net	3,086.9
Total assets	25,635.0
Liabilities:
Current portion of debt and finance lease obligations	3,220.9
Other accrued and current liabilities	2,242.0
Long-term debt and finance lease obligations	16,905.1
Other long-term liabilities	1,788.2
Total liabilities	$ 24,156.2