Fair Value Measurements (Assets and Liabilities Reconciliation) (Schedule and Footnote) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2015 USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance of net assets at January 1, 2015	$ 630.2
Losses included in net loss (a):
Realized and unrealized losses on derivative instruments, net	(229.7)
Realized and unrealized losses due to changes in fair values of certain investments, net	(1.5)
Foreign currency translation adjustments and other, net	(9.5)
Balance of net assets at June 30, 2015	389.5
Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance of net assets at January 1, 2015	318.4
Losses included in net loss (a):
Realized and unrealized losses on derivative instruments, net	0.0
Realized and unrealized losses due to changes in fair values of certain investments, net	(1.5)
Foreign currency translation adjustments and other, net	3.2
Balance of net assets at June 30, 2015	320.1
Equity-related derivative instruments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance of net assets at January 1, 2015	311.8
Losses included in net loss (a):
Realized and unrealized losses on derivative instruments, net	(229.7)
Realized and unrealized losses due to changes in fair values of certain investments, net	0.0
Foreign currency translation adjustments and other, net	(12.7)
Balance of net assets at June 30, 2015	$ 69.4