Derivative Instruments (Impact of Derivative Instruments on Borrowing Costs) (Details)	Sep. 30, 2018
Derivative [Line Items]
Impact of derivative instruments on borrowing costs	(0.33%)
Virgin Media
Derivative [Line Items]
Impact of derivative instruments on borrowing costs	(0.41%)
UPC Holding
Derivative [Line Items]
Impact of derivative instruments on borrowing costs	(0.02%)
Telenet
Derivative [Line Items]
Impact of derivative instruments on borrowing costs	(0.48%)