Earnings or Loss per Share (Schedules) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Loss from continuing operations	$ (396.7)	$ (561.9)	$ (1,093.0)	$ (1,688.7)
Net earnings from continuing operations attributable to noncontrolling interests	(51.2)	(23.2)	(93.4)	(63.0)
Net loss from continuing operations attributable to Liberty Global shareholders	$ (447.9)	$ (585.1)	$ (1,186.4)	$ (1,751.7)
Weighted average ordinary shares outstanding - basic and diluted (in shares)	793,544,759	830,301,600	787,649,342	857,905,832

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Amount after tax of income (loss) from continuing operations attributable to the parent.

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Amount after tax of income (loss) from continuing operations attributable to the noncontrolling interest.

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Amount after tax of income (loss) from continuing operations including portion attributable to the noncontrolling interest.

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Average number of shares or units issued and outstanding that are used in calculating basic and diluted earnings per share (EPS).

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