Fair Value Measurements (Assets and Liabilities Reconciliation) (Schedule and Footnote) (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2020	Dec. 31, 2019
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance of net assets (liabilities) at January 1, 2020	$ 1,063.5
Gains included in loss from continuing operations
Realized and unrealized gains (losses) on derivative instruments, net	154.1
Realized and unrealized gains due to changes in fair values of certain investments and debt, net	34.7
Additions	60.8
Reclassification of liability to held for sale	149.5
Transfers out of Level 3	6.8
Foreign currency translation adjustments and other, net	7.2
Balance of net assets (liabilities) at September 30, 2020	1,098.3
Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance of net assets (liabilities) at January 1, 2020	420.0
Gains included in loss from continuing operations
Realized and unrealized gains (losses) on derivative instruments, net	0.0
Realized and unrealized gains due to changes in fair values of certain investments and debt, net	34.7
Additions	60.8
Reclassification of liability to held for sale	0.0
Transfers out of Level 3	(2.0)
Foreign currency translation adjustments and other, net	6.4
Balance of net assets (liabilities) at September 30, 2020	519.9
Cross-currency, interest rate and foreign currency derivative contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance of net assets (liabilities) at January 1, 2020	(161.3)	$ (19.9)
Gains included in loss from continuing operations
Realized and unrealized gains (losses) on derivative instruments, net	(300.6)
Realized and unrealized gains due to changes in fair values of certain investments and debt, net	0.0
Additions	0.0
Reclassification of liability to held for sale	149.5
Transfers out of Level 3	8.8
Foreign currency translation adjustments and other, net	0.9
Balance of net assets (liabilities) at September 30, 2020	(161.3)
Equity-related derivative instruments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance of net assets (liabilities) at January 1, 2020	739.7	$ 663.4
Gains included in loss from continuing operations
Realized and unrealized gains (losses) on derivative instruments, net	454.7
Realized and unrealized gains due to changes in fair values of certain investments and debt, net	0.0
Additions	0.0
Reclassification of liability to held for sale	0.0
Transfers out of Level 3	0.0
Foreign currency translation adjustments and other, net	(0.1)
Balance of net assets (liabilities) at September 30, 2020	739.7
ITV Collar
Gains included in loss from continuing operations
Partial settlement	(340.3)
ITV Collar \| Investments
Gains included in loss from continuing operations
Partial settlement	0.0
ITV Collar \| Cross-currency, interest rate and foreign currency derivative contracts
Gains included in loss from continuing operations
Partial settlement	0.0
ITV Collar \| Equity-related derivative instruments
Gains included in loss from continuing operations
Partial settlement	(340.3)
Lionsgate Forward
Gains included in loss from continuing operations
Partial settlement	(38.0)
Lionsgate Forward \| Investments
Gains included in loss from continuing operations
Partial settlement	0.0
Lionsgate Forward \| Cross-currency, interest rate and foreign currency derivative contracts
Gains included in loss from continuing operations
Partial settlement	0.0
Lionsgate Forward \| Equity-related derivative instruments
Gains included in loss from continuing operations
Partial settlement	$ (38.0)

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Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

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Amount of gain (loss) recognized in income from derivative asset (liability) after deduction of derivative liability (asset), measured at fair value on recurring basis using unobservable input (level 3).

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Fair value of financial instrument classified as derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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