Acquisitions (Pro Forma Information) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Business Combination and Asset Acquisition [Abstract]
Revenue (in millions)	$ 13,206.8	$ 12,978.4
Net loss from continuing operations attributable to Liberty Global shareholders (in millions)	$ (1,902.3)	$ (1,820.6)
Basic earnings (loss) (attributable to Liberty Global shareholders per share (in dollars per share)	$ (3.16)	$ (2.58)
Diluted earnings (loss) (attributable to Liberty Global shareholders per share (in dollars per share)	$ (3.16)	$ (2.58)