Fair Value Measurements (Assets and Liabilities Reconciliation) (Schedule and Footnote) (Details) $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance of net assets (liabilities) at January 1, 2019	$ 1,149.7
Gains included in net earnings (loss)
Realized and unrealized (gains) losses, net	(4.7)
Partial settlement of Lionsgate Forward	(18.1)
Additions	19.6
Derivative instruments settled in connection with the sale of the Vodafone Disposal Group	(72.0)
Transfers out of Level 3	8.4
Foreign currency translation adjustments and other, net	(2.9)
Balance of net assets (liabilities) at December 31, 2019	1,063.5
Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance of net assets (liabilities) at January 1, 2019	418.9
Gains included in net earnings (loss)
Realized and unrealized (gains) losses, net	(16.5)
Partial settlement of Lionsgate Forward	0.0
Additions	19.6
Derivative instruments settled in connection with the sale of the Vodafone Disposal Group	0.0
Transfers out of Level 3	0.0
Foreign currency translation adjustments and other, net	(2.0)
Balance of net assets (liabilities) at December 31, 2019	420.0
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, 2019	(14.1)
Gains included in net earnings (loss)
Realized and unrealized (gains) losses, net	58.7
Partial settlement of Lionsgate Forward	0.0
Additions	0.0
Derivative instruments settled in connection with the sale of the Vodafone Disposal Group	(72.0)
Transfers out of Level 3	8.4
Foreign currency translation adjustments and other, net	(0.9)
Balance of net assets (liabilities) at December 31, 2019	(19.9)
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, 2019	744.9
Gains included in net earnings (loss)
Realized and unrealized (gains) losses, net	(63.4)
Partial settlement of Lionsgate Forward	(18.1)
Additions	0.0
Derivative instruments settled in connection with the sale of the Vodafone Disposal Group	0.0
Transfers out of Level 3	0.0
Foreign currency translation adjustments and other, net	0.0
Balance of net assets (liabilities) at December 31, 2019	663.4
Vodafone Disposal Group \| Equity-related derivative instruments
Gains included in net earnings (loss)
Realized and unrealized (gains) losses, net	$ 72.0

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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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