Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information [Line Items]
Revenue	$ 2,949.1	$ 2,929.7	$ 3,015.6	$ 3,063.5	$ 2,987.8	$ 2,899.3	$ 2,746.8	$ 2,642.5	$ 11,957.9	$ 11,276.4	$ 13,731.1
Operating income (loss)	252.4	205.1	264.1	117.5	153.1	218.8	206.3	214.2	839.1	792.4	1,570.1
Effect of Accounting Change (note 2)					(4.4)	0.0	0.0	0.0
Net earnings (loss)	52.2	1,025.9	950.5	(1,178.6)	(1,022.0)	(779.0)	(652.4)	(267.2)	850.0	(2,720.6)	1,767.3
Net earnings (loss) attributable to Liberty Global shareholders	$ 25.1	$ 974.1	$ 912.6	$ (1,186.5)	(992.0)	(791.6)	(674.3)	(320.2)	$ 725.3	$ (2,778.1)	$ 1,705.3
Basic earnings (loss) attributable to Liberty Global shareholders per share (notes 3 and 6) (in dollars per share)	$ 0.03	$ 1.23	$ 1.16	$ (1.47)
Diluted earnings (loss) attributable to Liberty Global shareholders per share (notes 3 and 6) (in dollars per share)	$ 0.03	$ 1.23	$ 1.15	$ (1.47)
As previously reported
Quarterly Financial Information [Line Items]
Revenue	$ 2,949.1	$ 2,958.1	$ 3,045.1	$ 4,156.1	3,987.7	2,929.0	2,774.9	3,519.0
Operating income (loss)	252.4	208.6	263.9	493.1	495.8	221.6	208.9	427.1
Restatement adjustment | Vodafone Disposal Group and UPC Austria
Quarterly Financial Information [Line Items]
Revenue	0.0	0.0	0.0	(1,061.6)	(970.4)	0.0	0.0	(849.2)
Operating income (loss)	0.0	0.0	0.0	(372.7)	(334.5)	0.0	0.0	(210.4)
Restatement adjustment | UPC DTH
Quarterly Financial Information [Line Items]
Revenue	0.0	(28.4)	(29.5)	(31.0)	(29.5)	(29.7)	(28.1)	(27.3)
Operating income (loss)	$ 0.0	$ (3.5)	$ 0.2	$ (2.9)	$ (3.8)	$ (2.8)	$ (2.6)	$ (2.5)
Liberty Global Shares
Quarterly Financial Information [Line Items]
Basic and diluted loss attributable to Liberty Global shareholders per share (notes 3 and 5) (in dollars per share)					$ (0.68)	$ (0.55)	$ (0.75)	$ (0.33)
LiLAC Shares
Quarterly Financial Information [Line Items]
Basic and diluted loss attributable to Liberty Global shareholders per share (notes 3 and 5) (in dollars per share)					$ (2.55)	$ (1.93)	$ (0.22)	$ (0.16)