Share-based Compensation (Share-Based Compensation Expense) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 67.3	$ 42.7
Other operating expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	0.9	1.0
SG&A expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	66.4	41.7
Liberty Global
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	61.8	37.8
Performance-based incentive awards | Liberty Global
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	29.9	8.7
Non-performance based share-based incentive awards | Liberty Global
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	22.0	22.0
Other
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	5.5	4.9
Other | Liberty Global
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 9.9	$ 7.1