Derivative Instruments (Basis Swaps, Interest Rate Caps and Collars) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Interest Rate Caps
Derivative [Line Items]
Notional amount of derivative	$ 259.9
Interest Rate Collars
Derivative [Line Items]
Notional amount of derivative	$ 636.8
Virgin Media | Basis Swaps
Derivative [Line Items]
Weighted average remaining life	9 days
UPC Holding | Basis Swaps
Derivative [Line Items]
Weighted average remaining life	9 days
Telenet | Basis Swaps
Derivative [Line Items]
Weighted average remaining life	9 days
Notional amount due from counterparty | Virgin Media | Basis Swaps
Derivative [Line Items]
Notional amount of derivative	$ 4,569.4
Notional amount due from counterparty | UPC Holding | Basis Swaps
Derivative [Line Items]
Notional amount of derivative	1,645.0
Notional amount due from counterparty | Telenet | Basis Swaps
Derivative [Line Items]
Notional amount of derivative	$ 2,075.0