Acquisitions and Dispositions (Pro Forma Information) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
Acquisitions and Dispositions [Abstract]
Revenue (in millions)	$ 3,337.8	$ 9,695.3
Net loss attributable to Liberty Global shareholders (in millions)	$ (1,070.8)	$ (756.8)
Basic earnings (loss) (attributable to Liberty Global shareholders per share (in dollars per share)	$ (1.81)	$ (1.24)
Diluted earnings (loss) (attributable to Liberty Global shareholders per share (in dollars per share)	$ (1.81)	$ (1.24)