Fair Value Measurements (Summary of Assets and Liabilities at Fair Value) (Schedule) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets - derivative instruments	$ 2,496.7	$ 2,127.7
Investments measured at fair value	1,174.8	2,315.3
Total assets	3,671.5	4,443.0
Liabilities - derivative instruments	1,370.7	1,781.2
Debt	248.6	926.6
Total liabilities	1,619.3	2,707.8
Quoted prices in active markets for identical assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets - derivative instruments	0.0	0.0
Investments measured at fair value	755.9	1,908.7
Total assets	755.9	1,908.7
Liabilities - derivative instruments	0.0	0.0
Debt	0.0	621.7
Total liabilities	0.0	621.7
Significant other observable inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets - derivative instruments	1,750.1	1,566.6
Investments measured at fair value	0.0	0.0
Total assets	1,750.1	1,566.6
Liabilities - derivative instruments	1,354.9	1,772.4
Debt	248.6	304.9
Total liabilities	1,603.5	2,077.3
Significant unobservable inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets - derivative instruments	746.6	561.1
Investments measured at fair value	418.9	406.6
Total assets	1,165.5	967.7
Liabilities - derivative instruments	15.8	8.8
Debt	0.0	0.0
Total liabilities	15.8	8.8
Cross Currency Interest Rate Contract
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets - derivative instruments	1,742.8	1,548.9
Liabilities - derivative instruments	1,368.7	1,767.9
Cross Currency Interest Rate Contract \| Quoted prices in active markets for identical assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets - derivative instruments	0.0	0.0
Liabilities - derivative instruments	0.0	0.0
Cross Currency Interest Rate Contract \| Significant other observable inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets - derivative instruments	1,742.5	1,548.7
Liabilities - derivative instruments	1,354.3	1,764.5
Cross Currency Interest Rate Contract \| Significant unobservable inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets - derivative instruments	0.3	0.2
Liabilities - derivative instruments	14.4	3.4
Equity-related derivative instruments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets - derivative instruments	746.3	560.9
Liabilities - derivative instruments	1.4	5.4
Equity-related derivative instruments \| Quoted prices in active markets for identical assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets - derivative instruments	0.0	0.0
Liabilities - derivative instruments	0.0	0.0
Equity-related derivative instruments \| Significant other observable inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets - derivative instruments	0.0	0.0
Liabilities - derivative instruments	0.0	0.0
Equity-related derivative instruments \| Significant unobservable inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets - derivative instruments	746.3	560.9
Liabilities - derivative instruments	1.4	5.4
Foreign Exchange Contract
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets - derivative instruments	7.2	17.1
Liabilities - derivative instruments	0.5	7.9
Foreign Exchange Contract \| Quoted prices in active markets for identical assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets - derivative instruments	0.0	0.0
Liabilities - derivative instruments	0.0	0.0
Foreign Exchange Contract \| Significant other observable inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets - derivative instruments	7.2	17.1
Liabilities - derivative instruments	0.5	7.9
Foreign Exchange Contract \| Significant unobservable inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets - derivative instruments	0.0	0.0
Liabilities - derivative instruments	0.0	0.0
Other Contract
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets - derivative instruments	0.4	0.8
Liabilities - derivative instruments	0.1	0.0
Other Contract \| Quoted prices in active markets for identical assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets - derivative instruments	0.0	0.0
Liabilities - derivative instruments	0.0
Other Contract \| Significant other observable inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets - derivative instruments	0.4	0.8
Liabilities - derivative instruments		0.1
Other Contract \| Significant unobservable inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets - derivative instruments	0.0	$ 0.0
Liabilities - derivative instruments	$ 0.0

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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