Debt and Capital Lease Obligations (VM Credit Facility) (Details)	12 Months Ended										12 Months Ended		12 Months Ended				12 Months Ended					12 Months Ended
	Dec. 31, 2014 VM Credit Facility [Member] USD ($)	Dec. 31, 2014 VM Credit Facility [Member] GBP (£)	Dec. 31, 2014 VM Credit Facility A [Member] USD ($)	Dec. 31, 2014 VM Credit Facility A [Member] GBP (£)	Jun. 07, 2013 VM Credit Facility A [Member] USD ($)	Jun. 07, 2013 VM Credit Facility A [Member] GBP (£)	Apr. 30, 2014 VM Credit Facility C [Member] USD ($)	Apr. 30, 2014 VM Credit Facility C [Member] GBP (£)	Jun. 07, 2013 VM Credit Facility C [Member] USD ($)	Jun. 07, 2013 VM Credit Facility C [Member] GBP (£)	Dec. 31, 2014 VM Credit Facility B [Member] USD ($)	Jun. 07, 2013 VM Credit Facility B [Member] GBP (£)	Dec. 31, 2014 VM Credit Facility D [Member] USD ($)	Dec. 31, 2014 VM Credit Facility D [Member] GBP (£)	Apr. 30, 2014 VM Credit Facility D [Member] USD ($)	Apr. 30, 2014 VM Credit Facility D [Member] GBP (£)	Dec. 31, 2014 VM Credit Facility E [Member] USD ($)	Dec. 31, 2014 VM Credit Facility E [Member] GBP (£)	Apr. 30, 2014 VM Credit Facility E [Member] USD ($)	Apr. 30, 2014 VM Credit Facility E [Member] GBP (£)	Dec. 31, 2014 VM Credit Facility B, D and E [Member]	Dec. 31, 2014 VM Revolving Credit Facility [Member] USD ($)	Dec. 31, 2014 VM Revolving Credit Facility [Member] GBP (£)	Jun. 07, 2013 VM Revolving Credit Facility [Member] USD ($)	Jun. 07, 2013 VM Revolving Credit Facility [Member] GBP (£)
Debt Instrument [Line Items]
Facility amount				£ 375,000,000	$ 584,300,000	£ 375,000,000			$ 934,900,000	£ 600,000,000	$ 2,755,000,000	£ 2,755,000,000		£ 100,000,000	$ 155,800,000	£ 100,000,000		£ 849,400,000	$ 1,323,500,000	£ 849,400,000			£ 660,000,000	$ 1,028,400,000	£ 660,000,000
Unused borrowing capacity	1,028,400,000		0								0		0				0					1,028,400,000
Outstanding principal amount	4,804,000,000		584,300,000				779,700,000	500,400,000			2,744,000,000		155,400,000				1,320,300,000					0
Description of variable rate basis			LIBOR	LIBOR							LIBOR		LIBOR	LIBOR			LIBOR	LIBOR				LIBOR	LIBOR
Basis spread on variable rate			3.25%	3.25%							2.75%		3.25%	3.25%			3.50%	3.50%				3.25%	3.25%
EBITDA Minimum Percentage	80.00%	80.00%
Minimum term after change in control lenders may cancel commitments	30 days	30 days
Portion of debt, default of which triggers event of default	$ 77,900,000	£ 50,000,000
LIBOR interest rate floor																					0.75%
Fee on unused portion of credit facility																						1.30%	1.30%