Fair Value Measurements (Assets and Liabilities Reconciliation) (Schedule and Footnote) (Details) $ in Millions	3 Months Ended
Mar. 31, 2021 USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance of net assets at January 1, 2021	$ 800.5
Gains included in net earnings (loss)
Realized and unrealized gains on derivative instruments, net	203.9
Realized and unrealized gains due to changes in fair values of certain investments and debt, net	100.9
Additions	4.3
Reclassification of liability to held for sale	(179.4)
Foreign currency translation adjustments and other, net	(6.2)
Balance of net assets at March 31, 2021	759.1
Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance of net assets at January 1, 2021	519.6
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	100.9
Additions	4.3
Reclassification of liability to held for sale	0.0
Foreign currency translation adjustments and other, net	(6.1)
Balance of net assets at March 31, 2021	618.7
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 at January 1, 2021	0.0
Gains included in net earnings (loss)
Realized and unrealized gains on derivative instruments, net	179.4
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	(179.4)
Foreign currency translation adjustments and other, net	0.0
Balance of net assets at March 31, 2021	0.0
Equity-related derivative instruments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance of net assets at January 1, 2021	280.9
Gains included in net earnings (loss)
Realized and unrealized gains on derivative instruments, net	24.5
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
Foreign currency translation adjustments and other, net	(0.1)
Balance of net assets at March 31, 2021	140.4
ITV Collar
Gains included in net earnings (loss)
Reclassification of liability to held for sale	(164.9)
ITV Collar \| Investments
Gains included in net earnings (loss)
Reclassification of liability to held for sale	0.0
ITV Collar \| Cross-currency, interest rate and foreign currency derivative contracts
Gains included in net earnings (loss)
Reclassification of liability to held for sale	0.0
ITV Collar \| Equity-related derivative instruments
Gains included in net earnings (loss)
Reclassification of liability to held for sale	$ (164.9)

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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 purchases of financial instrument classified as an 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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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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