Income Taxes (Narrative) (Details) (USD $)	12 Months Ended			0 Months Ended	1 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2014	Apr. 30, 2014	Apr. 30, 2015
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Change in valuation allowances	$ 373,400,000
Net operating losses from deductions of stock based compensation excluded from recorded deferred tax assets	141,700,000
Deferred tax liability, temporary difference	11,100,000,000
Unrecognized tax benefits - favorable impact on effective income tax rate if ultimately recognized, net of valuation allowances	332,900,000
Reasonably possible resolution of ongoing income tax examinations, reduction to unrecognized tax benefits, upper bound	230,000,000
Accrued interest and penalties on tax related items	51,700,000
Virgin Media [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Amount on which future tax deductions can be claimed	21,600,000,000	22,200,000,000
Maximum percent of capital allowances claimed allowance	18.00%
Continuing operations [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Change in valuation allowances related to net tax expense	(361,200,000)
Benefit (expense) from release (accrual) of interest and penalties	$ (10,900,000)	$ (14,000,000)	$ (7,700,000)
Domestic Tax Authority [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Statutory income tax rate				23.00%	21.00%
Domestic Tax Authority [Member] | Scenario, Forecast [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Statutory income tax rate						20.00%
Foreign Tax Authority [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Statutory income tax rate	35.00%