Derivative Instruments (Cross-currency Derivative Contracts) (Details) € in Millions, zł in Millions, SFr in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2021 USD ($)	Sep. 30, 2021 EUR (€)	Sep. 30, 2021 CHF (SFr)	Sep. 30, 2021 PLN (zł)
Derivative [Line Items]
Floor rate	0.000	0.000	0.000	0.000
UPC Holding | Cross-Currency Swap 1
Derivative [Line Items]
Weighted average remaining life	4 years
UPC Holding | Cross-Currency Swap 2
Derivative [Line Items]
Weighted average remaining life	6 years 7 months 6 days
UPC Holding | Cross-Currency Swap 3
Derivative [Line Items]
Weighted average remaining life	4 years 4 months 24 days
UPC Holding | Cross-Currency Swap 4
Derivative [Line Items]
Weighted average remaining life	4 years 3 months 18 days
UPC Holding | Cross-Currency Swap 5
Derivative [Line Items]
Weighted average remaining life	1 year 3 months 18 days
Telenet | Cross-Currency Swap 6
Derivative [Line Items]
Weighted average remaining life	5 years 3 months 18 days
Telenet | Cross-Currency Swap 7
Derivative [Line Items]
Weighted average remaining life	3 years 3 months 18 days
Virgin Media
Derivative [Line Items]
Derivative instruments that do not involve the exchange of notional amounts at the inception and maturity | $	$ 52.3
Notional amount due from counterparty | UPC Holding | Cross-Currency Swap 1
Derivative [Line Items]
Notional amount of derivative | $	360.0
Notional amount due from counterparty | UPC Holding | Cross-Currency Swap 2
Derivative [Line Items]
Notional amount of derivative | $	4,650.0
Notional amount due from counterparty | UPC Holding | Cross-Currency Swap 3
Derivative [Line Items]
Notional amount of derivative		€ 2,650.0
Notional amount due from counterparty | UPC Holding | Cross-Currency Swap 4
Derivative [Line Items]
Notional amount of derivative		777.0
Notional amount due from counterparty | UPC Holding | Cross-Currency Swap 5
Derivative [Line Items]
Notional amount of derivative | SFr			SFr 740.0
Notional amount due from counterparty | Telenet | Cross-Currency Swap 6
Derivative [Line Items]
Notional amount of derivative | $	3,940.0
Notional amount due from counterparty | Telenet | Cross-Currency Swap 7
Derivative [Line Items]
Notional amount of derivative		45.2
Notional amount due to counterparty | UPC Holding | Cross-Currency Swap 1
Derivative [Line Items]
Notional amount of derivative		267.9
Notional amount due to counterparty | UPC Holding | Cross-Currency Swap 2
Derivative [Line Items]
Notional amount of derivative | SFr			4,256.9
Notional amount due to counterparty | UPC Holding | Cross-Currency Swap 3
Derivative [Line Items]
Notional amount of derivative | SFr			SFr 2,970.1
Notional amount due to counterparty | UPC Holding | Cross-Currency Swap 4
Derivative [Line Items]
Notional amount of derivative | zł				zł 3,302.9
Notional amount due to counterparty | UPC Holding | Cross-Currency Swap 5
Derivative [Line Items]
Notional amount of derivative		701.1
Notional amount due to counterparty | Telenet | Cross-Currency Swap 6
Derivative [Line Items]
Notional amount of derivative		€ 3,489.6
Notional amount due to counterparty | Telenet | Cross-Currency Swap 7
Derivative [Line Items]
Notional amount of derivative | $	$ 50.0