Fair Value Measurements (Assets and Liabilities Reconciliation) (Schedule and Footnote) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2016 USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance of net assets at January 1, 2016	$ 668.7
Gains included in net earnings (loss)
Realized and unrealized gains on derivative instruments, net	666.3
Realized and unrealized gains due to changes in fair values of certain investments and debt, net	95.0
Partial settlement of Sumitomo Collar	(83.2)
Additions	25.2
Foreign currency translation adjustments and other, net	(0.1)
Balance of net assets at June 30, 2016	1,371.9
Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance of net assets at January 1, 2016	334.6
Gains included in net earnings (loss)
Realized and unrealized gains on derivative instruments, net	0.0
Realized and unrealized gains due to changes in fair values of certain investments and debt, net	95.0
Partial settlement of Sumitomo Collar	0.0
Additions	25.2
Foreign currency translation adjustments and other, net	2.3
Balance of net assets at June 30, 2016	457.1
Cross-currency and interest rate derivative contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance of net assets at January 1, 2016	0.0
Gains included in net earnings (loss)
Realized and unrealized gains on derivative instruments, net	(5.3)
Realized and unrealized gains due to changes in fair values of certain investments and debt, net	0.0
Partial settlement of Sumitomo Collar	0.0
Additions	0.0
Foreign currency translation adjustments and other, net	0.0
Balance of net assets at June 30, 2016	(5.3)
Equity-related derivative instruments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance of net assets at January 1, 2016	334.1
Gains included in net earnings (loss)
Realized and unrealized gains on derivative instruments, net	671.6
Realized and unrealized gains due to changes in fair values of certain investments and debt, net	0.0
Partial settlement of Sumitomo Collar	(83.2)
Additions	0.0
Foreign currency translation adjustments and other, net	(2.4)
Balance of net assets at June 30, 2016	$ 920.1