Fair Value Measurements (Assets and Liabilities Reconciliation) (Schedule and Footnote) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance of net assets at January 1, 2014	$ 612.9
Partial settlement of the Ziggo Collar (a)	17.9
Gains included in net loss (b):
Realized and unrealized gains on derivative instruments, net	24.1
Realized and unrealized gains due to changes in fair values of certain investments, net	8.9
Foreign currency translation adjustments and other	1.4
Balance of net assets at March 31, 2014	665.2
Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance of net assets at January 1, 2014	299.4
Partial settlement of the Ziggo Collar (a)	0
Gains included in net loss (b):
Realized and unrealized gains on derivative instruments, net	0
Realized and unrealized gains due to changes in fair values of certain investments, net	8.9
Foreign currency translation adjustments and other	0.7
Balance of net assets at March 31, 2014	309.0
Equity-related derivative instruments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance of net assets at January 1, 2014	313.5
Partial settlement of the Ziggo Collar (a)	17.9
Gains included in net loss (b):
Realized and unrealized gains on derivative instruments, net	24.1
Realized and unrealized gains due to changes in fair values of certain investments, net	0
Foreign currency translation adjustments and other	0.7
Balance of net assets at March 31, 2014	$ 356.2