Investments (Equity Method Investments) (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Schedule of Equity Method Investments [Line Items]
Share of results of affiliates, net (note 5)		$ (8.1)		$ (105.4)		$ (6.4)	$ (72.0)
Revenue		3,105.5		2,722.9		6,720.8	5,598.7
Loss before income taxes		11,457.3		(661.8)		13,068.1	436.0
Net loss		11,174.5	$ 1,440.3	(503.8)	$ 1,017.7	12,614.8	513.9
All3Media Group (All3Media)
Schedule of Equity Method Investments [Line Items]
Share of results of affiliates, net (note 5)		(5.8)		(14.9)		(14.8)	(39.8)
VodafoneZiggo JV
Schedule of Equity Method Investments [Line Items]
Share of results of affiliates, net (note 5)		4.7		(89.2)		9.4	(28.1)
VodafoneZiggo JV | Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Revenue		1,215.3		1,081.6		2,432.3	2,178.7
Loss before income taxes		(19.6)		(151.8)		(41.0)	(26.9)
Net loss		(15.5)		(185.4)		(31.6)	(85.7)
Formula E Holdings Ltd (Formula E)
Schedule of Equity Method Investments [Line Items]
Share of results of affiliates, net (note 5)		(4.3)		1.9		4.4	0.7
VMED O2 JV
Schedule of Equity Method Investments [Line Items]
Share of results of affiliates, net (note 5)		(0.3)		0.0		(0.3)	0.0
VMED O2 JV | Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Revenue	$ 1,208.5	1,208.5		0.0		1,208.5	0.0
Loss before income taxes	(168.5)
Net loss	$ (34.6)
Other
Schedule of Equity Method Investments [Line Items]
Share of results of affiliates, net (note 5)		$ (2.4)		$ (3.2)		$ (5.1)	$ (4.8)