Derivative Instruments (Realized and Unrealized Gains (Losses) on Derivatives) (Schedule and Footnotes) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivative [Line Items]
Gain (loss) on derivative instruments, net	$ 65.5	$ (187.4)	$ 529.7	$ (783.5)
Cross-currency and interest rate derivative contracts
Derivative [Line Items]
Gain (loss) on derivative instruments, net	(18.4)	(188.4)	489.8	(847.5)
Equity-related derivative instruments:
Derivative [Line Items]
Gain (loss) on derivative instruments, net	76.9	8.6	19.7	90.1
ITV Collar
Derivative [Line Items]
Gain (loss) on derivative instruments, net	76.5	44.2	16.5	154.4
Lionsgate Forward
Derivative [Line Items]
Gain (loss) on derivative instruments, net	0.2	(7.3)	12.6	(9.3)
Sumitomo Collar
Derivative [Line Items]
Gain (loss) on derivative instruments, net	0.0	(29.5)	(11.8)	(50.8)
Other
Derivative [Line Items]
Gain (loss) on derivative instruments, net	0.2	1.2	2.4	(4.2)
Foreign currency forward and option contracts
Derivative [Line Items]
Gain (loss) on derivative instruments, net	6.7	(7.5)	20.6	(26.5)
Other
Derivative [Line Items]
Gain (loss) on derivative instruments, net	$ 0.3	$ (0.1)	$ (0.4)	$ 0.4