Derivative Instruments (Basis Swaps, Interest Rate Caps and Collars) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2017 USD ($)
Interest Rate Cap [Member]
Derivative [Line Items]
Notional amount of derivative	$ 603.7
Interest Rate Collar [Member]
Derivative [Line Items]
Notional amount of derivative	$ 669.8
Virgin Media [Member] | Basis Swap [Member]
Derivative [Line Items]
Weighted average remaining life	7 months 6 days
UPC Holding [Member] | Basis Swap [Member]
Derivative [Line Items]
Weighted average remaining life	9 months 18 days
Unitymedia [Member] | Basis Swap [Member]
Derivative [Line Items]
Weighted average remaining life	1 year
Telenet [Member] | Basis Swap [Member]
Derivative [Line Items]
Weighted average remaining life	9 months 18 days
C&W [Member] | Basis Swap [Member]
Derivative [Line Items]
Weighted average remaining life	9 months 18 days
Due From Counterparty [Member] | Virgin Media [Member] | Basis Swap [Member]
Derivative [Line Items]
Notional amount of derivative	$ 7,958.6
Due From Counterparty [Member] | UPC Holding [Member] | Basis Swap [Member]
Derivative [Line Items]
Notional amount of derivative	4,300.0
Due From Counterparty [Member] | Unitymedia [Member] | Basis Swap [Member]
Derivative [Line Items]
Notional amount of derivative	855.0
Due From Counterparty [Member] | Telenet [Member] | Basis Swap [Member]
Derivative [Line Items]
Notional amount of derivative	4,100.0
Due From Counterparty [Member] | C&W [Member] | Basis Swap [Member]
Derivative [Line Items]
Notional amount of derivative	$ 2,925.0