Derivative Instruments (Realized and Unrealized Gains (Losses) on Derivatives) (Schedule and Footnotes) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Derivative [Line Items]
Gain (loss) on derivative instruments, net	$ (514.5)	$ 1,052.0	$ (783.6)	$ 543.3
Cross-Currency and Interest Rate Derivative Contracts [Member]
Derivative [Line Items]
Gain (loss) on derivative instruments, net	(668.7)	656.2	(848.0)	(116.8)
Foreign Currency Forwards and Option Contracts [Member]
Derivative [Line Items]
Gain (loss) on derivative instruments, net	(9.5)	18.0	(17.8)	(10.8)
Liberty Global Group [Member]
Derivative [Line Items]
Gain (loss) on derivative instruments, net	(505.3)	1,097.4	(747.1)	733.4
Liberty Global Group [Member] | Cross-Currency and Interest Rate Derivative Contracts [Member]
Derivative [Line Items]
Gain (loss) on derivative instruments, net	(656.9)	699.8	(810.7)	64.4
Liberty Global Group [Member] | Equity-Related Derivative Instruments [Member]
Derivative [Line Items]
Gain (loss) on derivative instruments, net	163.5	378.4	81.5	671.6
Liberty Global Group [Member] | ITV Collar [Member]
Derivative [Line Items]
Gain (loss) on derivative instruments, net	163.4	308.3	110.2	513.7
Liberty Global Group [Member] | Sumitomo Collar [Member]
Derivative [Line Items]
Gain (loss) on derivative instruments, net	2.2	66.3	(21.3)	135.0
Liberty Global Group [Member] | Lionsgate Forward [Member]
Derivative [Line Items]
Gain (loss) on derivative instruments, net	(2.5)	3.3	(2.0)	22.0
Liberty Global Group [Member] | Other [Member]
Derivative [Line Items]
Gain (loss) on derivative instruments, net	0.4	0.5	(5.4)	0.9
Liberty Global Group [Member] | Foreign Currency Forwards and Option Contracts [Member]
Derivative [Line Items]
Gain (loss) on derivative instruments, net	(12.1)	19.8	(18.6)	(1.9)
Liberty Global Group [Member] | Other Contract [Member]
Derivative [Line Items]
Gain (loss) on derivative instruments, net	0.2	(0.6)	0.7	(0.7)
LiLAC Group [Member]
Derivative [Line Items]
Gain (loss) on derivative instruments, net	(9.2)	(45.4)	(36.5)	(190.1)
LiLAC Group [Member] | Cross-Currency and Interest Rate Derivative Contracts [Member]
Derivative [Line Items]
Gain (loss) on derivative instruments, net	(11.8)	(43.6)	(37.3)	(181.2)
LiLAC Group [Member] | Foreign Currency Forwards and Option Contracts [Member]
Derivative [Line Items]
Gain (loss) on derivative instruments, net	$ 2.6	$ (1.8)	$ 0.8	$ (8.9)