Fair Value Measurements (Summary of Assets and Liabilities at Fair Value) (Schedule) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments	$ 1,589.5	$ 1,470.3
SMAs	1,797.7	2,854.6
Other investments	3,211.6	2,038.4
Total investments	5,009.3	4,893.0
Total assets	6,598.8	6,363.3
Derivative instruments	861.8	747.1
Total liabilities	861.8	747.1
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	430.3	943.2
Other investments	1,649.4	399.3
Total investments	2,079.7	1,342.5
Total assets	2,079.7	1,342.5
Total liabilities	0.0	0.0
Significant other observable inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments	1,360.4	1,470.3
SMAs	1,367.4	1,911.4
Other investments	0.1	0.1
Total investments	1,367.5	1,911.5
Total assets	2,727.9	3,381.8
Total liabilities	774.5	747.1
Significant unobservable inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments	229.1	0.0
SMAs	0.0	0.0
Other investments	1,562.1	1,639.0
Total investments	1,562.1	1,639.0
Total assets	1,791.2	1,639.0
Total liabilities	87.3	0.0
Cross-currency and interest rate derivative contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments	1,356.8	1,469.0
Derivative instruments	772.5	735.5
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	1,356.8	1,469.0
Derivative instruments	772.5	735.5
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	229.1	0.0
Derivative instruments	87.3	0.0
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
Derivative instruments	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
Derivative instruments	0.0
Equity-related derivative instruments | Significant unobservable inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments	229.1
Derivative instruments	87.3
Foreign currency forward and option contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments	3.4	1.0
Derivative instruments	2.0	11.6
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	3.4	1.0
Derivative instruments	2.0	11.6
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	0.2	0.3
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	0.0
Other | Significant other observable inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments	0.2	0.3
Other | Significant unobservable inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments	$ 0.0	$ 0.0