Derivative Instruments (Net Cash Received (Paid) Related to Derivatives) (Schedule) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Derivative [Line Items]
Operating activities	$ 94.2	$ 1.3
Investing activities	(2.1)	(0.4)
Total	(47.4)	(42.4)
Liberty Global Group [Member]
Derivative [Line Items]
Operating activities	112.4	(1.5)
Investing activities	(0.5)	0.0
Financing activities	(139.5)	(43.3)
Total	(27.6)	(44.8)
LiLAC Group [Member]
Derivative [Line Items]
Operating activities	(18.2)	2.8
Investing activities	(1.6)	(0.4)
Total	$ (19.8)	$ 2.4