Derivative Instruments (Interest Rate Swap Contracts and Options) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Interest Rate Swaption 1 [Member] | Virgin Media [Member]
Derivative [Line Items]
Notional amount of derivative	$ 7,445.5
Weighted average remaining life	1 year 6 months
Weighted average strike rate	2.45%
Interest Rate Swaption 2 [Member] | Virgin Media [Member]
Derivative [Line Items]
Notional amount of derivative	$ 878.4
Weighted average remaining life	1 year 2 months 12 days
Weighted average strike rate	1.98%
Interest Rate Swaption [Member] | UPC Holding [Member]
Derivative [Line Items]
Notional amount of derivative	$ 1,376.6
Weighted average remaining life	24 days
Weighted average strike rate	1.22%
Interest Rate Swaption [Member] | Unitymedia [Member]
Derivative [Line Items]
Notional amount of derivative	$ 4,372.2
Weighted average remaining life	1 year 7 months 6 days
Weighted average strike rate	1.93%
Due From Counterparty [Member] | Interest Rate Swap [Member] | Virgin Media [Member]
Derivative [Line Items]
Notional amount of derivative	$ 19,778.6
Weighted average remaining life	3 years 10 months 24 days
Due From Counterparty [Member] | Interest Rate Swap [Member] | UPC Holding [Member]
Derivative [Line Items]
Notional amount of derivative	$ 5,988.0
Weighted average remaining life	5 years 3 months 18 days
Due From Counterparty [Member] | Interest Rate Swap [Member] | Unitymedia [Member]
Derivative [Line Items]
Notional amount of derivative	$ 8,766.1
Weighted average remaining life	4 years 1 month 6 days
Due From Counterparty [Member] | Interest Rate Swap [Member] | Telenet [Member]
Derivative [Line Items]
Notional amount of derivative	$ 3,880.3
Weighted average remaining life	5 years 8 months 12 days
Due To Counterparty [Member] | Interest Rate Swap [Member] | Virgin Media [Member]
Derivative [Line Items]
Notional amount of derivative	$ 12,515.8
Weighted average remaining life	5 years 10 months 24 days
Due To Counterparty [Member] | Interest Rate Swap [Member] | UPC Holding [Member]
Derivative [Line Items]
Notional amount of derivative	$ 3,543.8
Weighted average remaining life	7 years 6 months
Due To Counterparty [Member] | Interest Rate Swap [Member] | Unitymedia [Member]
Derivative [Line Items]
Notional amount of derivative	$ 6,208.0
Weighted average remaining life	7 years 2 months 12 days
Due To Counterparty [Member] | Interest Rate Swap [Member] | Telenet [Member]
Derivative [Line Items]
Notional amount of derivative	$ 1,753.9
Weighted average remaining life	5 years 6 months