Share-based Compensation (Narrative) (Details) $ / shares in Units, $ in Millions		12 Months Ended
	Apr. 30, 2014 installment shares	Dec. 31, 2018 USD ($) installment $ / shares shares	Dec. 31, 2017 $ / shares shares	Dec. 31, 2016 shares	Dec. 31, 2015 shares	Dec. 31, 2018 € / shares	Jun. 24, 2013 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of annual inventive compensation		100.00%
Total compensation expense not yet recognized | $		$ 246.7
Weighted average period remaining for expense recognition		2 years 1 month 6 days
Options | Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards outstanding (in shares)		580,254	580,481
Awards outstanding (in EUR/USD per share) | $ / shares		$ 27.51	$ 25.54
Options exercisable and end of period (in shares)		417,608
Options | Class C
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards outstanding (in shares)		2,667,506	2,725,566
Awards outstanding (in EUR/USD per share) | $ / shares		$ 25.09	$ 25.58
Options exercisable and end of period (in shares)		2,161,408
PSUs | Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)		1,177,392
PSUs | Class C
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)		2,354,784
April 1 and October 1 of 2017 | PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			50.00%
Performance period			2 years
PSUs earned			99.50%
April 1, 2019 and October 1, 2019 | PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage		50.00%
Performance period		3 years
Adjusted OIBDA CAGR		6.00%
Liberty Global Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share authorized (in shares)		46,220,904
Liberty Global Incentive Plan | Awards other than Performance-Based Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award term		7 years
Liberty Global Incentive Plan | Six Month Anniversary After Grant Date
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage		12.50%
Liberty Global Incentive Plan | Each Quarter Thereafter after Six Month Vest
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage		6.25%
Liberty Global Director Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share authorized (in shares)		9,108,222
Award term		7 years
Number of equal or semi-equal installments | installment		3
2018 PSUs | PSUs | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance range		50.00%
Expected performance earnings for PSUs		50.00%
2018 PSUs | PSUs | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance range		125.00%
Expected performance earnings for PSUs		150.00%
2018 PSUs | April 1, 2020 | PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage		50.00%
2018 PSUs | October 1, 2020 | PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage		50.00%
Liberty Global 2014 Incentive Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share authorized (in shares)		105,000,000
Liberty Global 2014 Incentive Plans | Class B
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share authorized (in shares)		50,250,000
Liberty Global 2014 Incentive Plans | Anti-Dilution and Other Adjustment Provisions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share authorized (in shares)		10,500,000
Liberty Global Performance Grant Award | PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of equal or semi-equal installments | installment	3
Liberty Global Performance Grant Award | PSUs | Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	1,000,000
Liberty Global Performance Grant Award | PSUs | Class B
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	1,000,000
Liberty Global Challenge Performance Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award term		7 years
Liberty Global Challenge Performance Awards | Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of ordinary share rights for each performance share (in shares)							1
Liberty Global Challenge Performance Awards | June 24th, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage		100.00%
Telenet | Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards outstanding (in shares)		4,494,002
Awards outstanding (in EUR/USD per share) | (per share)		$ 48.67				€ 42.50
LiLAC Shares | CEO | Liberty Global Performance Grant Award | PSUs | Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)				41,589	33,333
LiLAC Shares | CEO | Liberty Global Performance Grant Award | PSUs | Class B
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)				41,589	33,333