Fair Value Measurements (Assets and Liabilities Reconciliation) (Schedule and Footnote) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 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 net earnings (loss)
Realized and unrealized gains (losses) on derivative instruments, net	389.7
Realized and unrealized losses due to changes in fair values of certain investments and debt, net	(16.1)
Additions	34.4
Transfers out of Level 3	7.3
Foreign currency translation adjustments and other, net	(1.3)
Balance of net assets (liabilities) at March 31, 2020	1,477.5
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 net earnings (loss)
Realized and unrealized losses due to changes in fair values of certain investments and debt, net	(16.1)
Additions	34.4
Transfers out of Level 3	0.0
Foreign currency translation adjustments and other, net	(2.8)
Balance of net assets (liabilities) at March 31, 2020	435.5
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	(11.7)	$ (19.9)
Gains included in net earnings (loss)
Realized and unrealized gains (losses) on derivative instruments, net	(0.7)
Additions	0.0
Transfers out of Level 3	7.3
Foreign currency translation adjustments and other, net	1.6
Balance of net assets (liabilities) at March 31, 2020	(11.7)
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	1,053.7	$ 663.4
Gains included in net earnings (loss)
Realized and unrealized gains (losses) on derivative instruments, net	390.4
Additions	0.0
Transfers out of Level 3	0.0
Foreign currency translation adjustments and other, net	(0.1)
Balance of net assets (liabilities) at March 31, 2020	$ 1,053.7

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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 transfer of financial instrument classified as an asset into (out of) level 3 of the fair value hierarchy.

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Amount of transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy.

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Fair value 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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Amount of transfers of financial instrument classified as derivative asset (liability) after deduction of derivative liability (asset) out of level 3 of the fair value hierarchy.

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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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