Acquisitions, Disposals and Discontinued Operations (Discontinued Operations) (Details) - LiLAC Group [Member] - Discontinued Operations, Disposed of by Means Other than Sale, Spinoff [Member] - USD ($)		3 Months Ended
	Dec. 29, 2017	Mar. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Common shares distributed	100.00%
Gain (loss) on discontinued operation	$ 0
Operating results of discontinued operations
Revenue		$ 910,900,000
Operating income (loss)		134,800,000
Earnings (loss) before income taxes and noncontrolling interests		33,700,000
Income tax expense		(44,600,000)
Net (earnings) loss attributable to noncontrolling interests		(16,400,000)
Net earnings (loss) attributable to Liberty Global shareholders, net of taxes, attributable to holders of:		$ (27,300,000)
Basic and diluted earnings (loss) attributable to Liberty Global shareholders per share:		$ (0.16)
Weighted average ordinary shares outstanding - basic and diluted (in shares)		172,743,854