Debt and Capital Lease Obligations (Refinancing Transactions) (Details) £ in Millions				1 Months Ended							3 Months Ended	12 Months Ended
	Oct. 04, 2018 EUR (€)	Oct. 04, 2018 USD ($)	Jul. 31, 2018 USD ($)	Oct. 31, 2018 USD ($)	Aug. 31, 2018 EUR (€)	Aug. 31, 2018 USD ($)	Aug. 31, 2018 GBP (£)	May 31, 2018 USD ($)	Mar. 31, 2018 EUR (€)	Mar. 31, 2018 USD ($)	Oct. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2018 USD ($)	Aug. 31, 2018 USD ($)	May 31, 2018 EUR (€)	May 31, 2018 USD ($)
Debt Instrument [Line Items]
Outstanding principal amount												$ 32,178,000,000.0		$ 29,315,300,000
Dividends	€ 351,600,000	$ 404,800,000
Telenet
Debt Instrument [Line Items]
Dividends | €					€ 600,000,000.0
UPC Holding Senior Notes
Debt Instrument [Line Items]
Outstanding principal amount												1,313,400,000		$ 1,215,500,000
Senior Notes | Virgin Media
Debt Instrument [Line Items]
Losses (gains) on debt modification and extinguishment											$ 36,400,000
Payment for debt redemption premium											28,200,000
Write-off of unamortized debt discount and deferred financing cost											$ 8,200,000
Senior Notes | 2023 VM Dollar Senior Notes
Debt Instrument [Line Items]
Extinguishment of debt						$ 190,000,000.0
Senior Notes | 2023 VM Sterling Senior Notes
Debt Instrument [Line Items]
Extinguishment of debt				$ 340,000,000.0		318,600,000	£ 250.0
Stated interest rate of debt					7.00%										7.00%
Senior Notes | UPC Holding Senior Notes
Debt Instrument [Line Items]
Losses (gains) on debt modification and extinguishment												112,100,000	$ 77,100,000
Payment for debt redemption premium												84,300,000	57,200,000
Write-off of unamortized debt discount and deferred financing cost												27,800,000	19,900,000
Long-term Debt
Debt Instrument [Line Items]
Extinguishment of debt			$ 1,500,000,000
Long-term Debt | Virgin Media
Debt Instrument [Line Items]
Losses (gains) on debt modification and extinguishment												67,500,000	78,400,000
Payment for debt redemption premium												32,600,000	52,600,000
Write-off of unamortized debt discount and deferred financing cost												40,600,000	25,800,000
Write-off of unamortized debt discount (premium)												(7,000,000.0)
Third-party debt modification costs												1,300,000
Line of Credit | UPC Holding
Debt Instrument [Line Items]
Losses (gains) on debt modification and extinguishment						8,900,000
Payment for debt redemption premium						2,000,000.0
Write-off of unamortized debt discount and deferred financing cost						6,900,000
Line of Credit | Telenet
Debt Instrument [Line Items]
Losses (gains) on debt modification and extinguishment								$ 7,600,000		$ 21,300,000
Payment for debt redemption premium										17,300,000
Write-off of unamortized debt discount and deferred financing cost										4,000,000.0
Line of Credit | UPC Facility AR
Debt Instrument [Line Items]
Extinguishment of debt						330,000,000.0
Line of Credit | UPC Facility AS
Debt Instrument [Line Items]
Extinguishment of debt					€ 500,000,000.0	572,600,000
Line of Credit | UPC Facility AK
Debt Instrument [Line Items]
Extinguishment of debt					60,000,000.0	68,700,000
Line of Credit | Telenet Facility AL Add-on
Debt Instrument [Line Items]
Extinguishment of debt								300,000,000.0
Line of Credit | Telenet Credit Facility AL
Debt Instrument [Line Items]
Extinguishment of debt								1,300,000,000.0
Line of Credit | Telenet Credit Facility V
Debt Instrument [Line Items]
Extinguishment of debt									€ 250,000,000.0	286,300,000
Line of Credit | Telenet Credit Facility AM
Debt Instrument [Line Items]
Extinguishment of debt								$ 730,000,000.0
Medium-term Notes | Telenet
Debt Instrument [Line Items]
Losses (gains) on debt modification and extinguishment										2,600,000
Payment for debt redemption premium										2,000,000.0
Write-off of unamortized debt discount and deferred financing cost										600,000
Medium-term Notes | UPCB Finance IV Euro Notes
Debt Instrument [Line Items]
Extinguishment of debt | €					60,000,000.0
Outstanding principal amount | €					€ 600,000,000.0
Medium-term Notes | Telenet Credit Facility AB
Debt Instrument [Line Items]
Extinguishment of debt									€ 530,000,000.0	$ 607,000,000.0
Stated interest rate of debt										4.875%
Percentage of principal amount redeemed									10.00%	10.00%
Medium-term Notes | Telenet Finance VI Notes
Debt Instrument [Line Items]
Extinguishment of debt										$ 530,000,000.0
Percentage of principal amount redeemed									10.00%	10.00%
Medium-term Notes | Telenet Finance V Notes
Debt Instrument [Line Items]
Extinguishment of debt | €									€ 250,000,000.0
Stated interest rate of debt										6.75%
Senior Notes | 2023 VM Dollar Senior Notes
Debt Instrument [Line Items]
Original issue amount															$ 530,000,000.0
Stated interest rate of debt				6.375%	6.375%						6.375%				6.375%
Line of Credit | Telenet
Debt Instrument [Line Items]
Dividends					€ 600,000,000.0	$ 687,100,000
Line of Credit | UPC Facility AR
Debt Instrument [Line Items]
Outstanding principal amount															$ 1,975,000,000.0
Line of Credit | Telenet Credit Facility AO
Debt Instrument [Line Items]
Original issue amount																€ 730,000,000.0	$ 836,000,000.0
Original issue price																99.875%	99.875%
Line of Credit | UPC Facility AK
Debt Instrument [Line Items]
Stated interest rate of debt					4.00%										4.00%
Outstanding principal amount					€ 600,000,000.0										$ 687,100,000
Line of Credit | Telenet Facility AL Add-on
Debt Instrument [Line Items]
Original issue amount										$ 300,000,000.0
Line of Credit | Telenet Facility AN
Debt Instrument [Line Items]
Original issue amount																	$ 1,600,000,000.0
Original issue price																99.875%	99.875%
Line of Credit | Telenet Facility AN Add-on
Debt Instrument [Line Items]
Original issue amount															$ 475,000,000.0
Original issue price					98.50%										98.50%
Line of Credit | Telenet Facility AO Add-on
Debt Instrument [Line Items]
Original issue amount					€ 205,000,000.0										$ 234,800,000
Original issue price					98.00%										98.00%
Line of Credit | LIBOR | UPC Facility AR
Debt Instrument [Line Items]
Basis spread on variable rate					2.50%	2.50%	2.50%
Floor interest rate					0.00%										0.00%
Line of Credit | LIBOR | Telenet Credit Facility AL
Debt Instrument [Line Items]
Basis spread on variable rate									2.50%	2.50%
Floor interest rate										0.00%
Line of Credit | LIBOR | Telenet Facility AN
Debt Instrument [Line Items]
Basis spread on variable rate								2.25%
Floor interest rate																0.00%	0.00%
Line of Credit | EURIBOR | UPC Facility AS
Debt Instrument [Line Items]
Basis spread on variable rate					2.75%	2.75%	2.75%
Line of Credit | EURIBOR | Telenet Credit Facility AO
Debt Instrument [Line Items]
Basis spread on variable rate								2.50%
Floor interest rate																0.00%	0.00%
Line of Credit | EURIBOR | Telenet Credit Facility AM
Debt Instrument [Line Items]
Basis spread on variable rate								2.75%
Medium-term Notes | Telenet
Debt Instrument [Line Items]
Losses (gains) on debt modification and extinguishment												75,700,000	52,800,000
Payment for debt redemption premium												21,500,000	19,000,000.0
Write-off of unamortized debt discount and deferred financing cost												$ 54,200,000	$ 33,800,000