Fair Value Measurements (Summary of Assets and Liabilities at Fair Value) (Schedule) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments:	$ 510.3	$ 884.7
SMAs	2,942.6	1,965.9
Other investments	1,855.7	1,500.1
Total investments	4,798.3	3,466.0
Total assets	5,308.6	4,350.7
Derivative instruments:	694.1	1,616.8
Total liabilities	694.1	1,616.8
Quoted prices in active markets for identical assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments:	0.0	0.0
SMAs	618.8	405.7
Other investments	740.4	888.2
Total investments	1,359.2	1,293.9
Total assets	1,359.2	1,293.9
Total liabilities	0.0	0.0
Significant other observable inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments:	395.9	603.8
SMAs	2,318.8	1,560.2
Other investments	71.5	92.3
Total investments	2,390.3	1,652.5
Total assets	2,786.2	2,256.3
Total liabilities	694.1	1,616.8
Significant unobservable inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments:	114.4	280.9
SMAs	5.0	0.0
Other investments	1,043.8	519.6
Total investments	1,048.8	519.6
Total assets	1,163.2	800.5
Total liabilities	0.0	0.0
Cross-currency and interest rate derivative contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments:	388.5	567.2
Derivative instruments:	663.0	1,535.3
Cross-currency and interest rate derivative contracts | Quoted prices in active markets for identical assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments:	0.0	0.0
Derivative instruments:	0.0	0.0
Cross-currency and interest rate derivative contracts | Significant other observable inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments:	388.5	567.2
Derivative instruments:	663.0	1,535.3
Cross-currency and interest rate derivative contracts | Significant unobservable inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments:	0.0	0.0
Derivative instruments:	0.0	0.0
Equity-related derivative instruments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments:	114.4	280.9
Equity-related derivative instruments | Quoted prices in active markets for identical assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
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]
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]
Derivative instruments:	114.4	280.9
Foreign currency forward and option contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments:	6.1	36.6
Derivative instruments:	31.1	81.5
Foreign currency forward and option contracts | Quoted prices in active markets for identical assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments:	0.0	0.0
Derivative instruments:	0.0	0.0
Foreign currency forward and option contracts | Significant other observable inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments:	6.1	36.6
Derivative instruments:	31.1	81.5
Foreign currency forward and option contracts | Significant unobservable inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments:	0.0	0.0
Derivative instruments:	0.0	0.0
Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments:	1.3	$ 0.0
Other | Quoted prices in active markets for identical assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments:	0.0
Other | Significant other observable inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments:	1.3
Other | Significant unobservable inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments:	$ 0.0