Investments (Narrative) (Details) In Millions, except Share data, unless otherwise specified	1 Months Ended															1 Months Ended
	Sep. 30, 2014 All3Media [Member] USD ($)	Sep. 30, 2014 All3Media [Member] EUR (€)	Sep. 30, 2014 DLG [Member] All3Media [Member]	Sep. 30, 2014 Ziggo N.V. [Member]	Sep. 30, 2014 Ziggo N.V. [Member] Ziggo Collar [Member]	Sep. 30, 2014 Ziggo N.V. [Member] Securities Subject to Re-Use Rights [Member]	Dec. 31, 2013 Ziggo N.V. [Member] Securities Subject to Re-Use Rights [Member]	Sep. 30, 2014 Ziggo N.V. [Member] Shares Borrowed as Hedge [Member]	Oct. 10, 2014 Ziggo N.V. [Member] Subsequent Event [Member] Ziggo Collar [Member]	Jul. 17, 2014 ITV [Member] USD ($)	Jul. 17, 2014 ITV [Member] GBP (£)	Jun. 30, 2014 ITV [Member]	Sep. 30, 2014 Sumitomo [Member]	Sep. 30, 2014 Cyfra, Privately Held DTH Operator in Poland [Member]	Sep. 30, 2014 DLG Acquisition Limited [Member]	Sep. 30, 2014 All3Media [Member] Discovery [Member] USD ($)	Sep. 30, 2014 All3Media [Member] Discovery [Member] GBP (£)
Investment [Line Items]
Number of common stock shares owned (in shares)				57,000,738	19,965,600	18,000,000	22,900,000	15,600,000		259,820,065	259,820,065		45,652,043
Shares lent to counterparty (in shares)									15,700,000
Percentage of total outstanding common stock shares owned				28.50%								6.40%	5.00%		50.00%
Price of investment (in GBP/USD per share)										$ 3.14	£ 1.85
Investment owned										$ 816.3	£ 480.7
Percentage of voting interests acquired			100.00%											17.00%
Cash contributions	$ 147.2	€ 90.0														$ 147.2	£ 90.0