Fair Value Measurements Fair Value Measurements (Reconciliation of Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs) (Details) - USD ($)
$ in Millions

3 Months Ended

9 Months Ended

Sep. 30, 2024

Sep. 30, 2023

Sep. 30, 2024

Sep. 30, 2023

Jun. 30, 2024

Dec. 31, 2023

Jun. 30, 2023

Dec. 31, 2022

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]

Investments, Fair Value Disclosure

$ 795.5

$ 792.8

$ 795.5

$ 792.8

$ 740.8

$ 794.9

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]

Investments, Fair Value Disclosure

378.8

64.2

378.8

64.2

$ 367.8

$ 367.3

$ 438.1

$ 452.0

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]

Business Combination, Contingent Consideration, Liability, Beginning Balance

53.7

64.3

57.5

73.2

Derivative Assets (Liabilities), at Fair Value, Net, Beginning Balance

31.7

59.1

10.3

20.7

Business Combination, Contingent Consideration, Liability, Ending Balance

35.2

438.7

35.2

438.7

Derivative Assets (Liabilities), at Fair Value, Net, Ending Balance

25.7

30.9

25.7

30.9

Earn-out Liabilities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings

(20.9)

0.1

(33.5)

(0.5)

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)

0.2

(0.1)

0.2

0.1

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases

2.4

0.0

13.4

0.0

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements

(0.2)

(0.1)

(2.2)

(8.6)

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3

0.0

(0.2)

0.0

Derivative [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings

17.3

18.0

45.5

56.9

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)

0.0

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases

32.8

25.3

78.9

93.8

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements

(56.1)

(71.5)

(109.0)

(140.5)

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3

0.0

Investments [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings

9.5

(2.0)

(0.9)

(101.0)

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)

1.5

(1.0)

1.2

0.2

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases

0.0

0.5

2.8

20.6

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements

$ 0.0

0.0

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3

$ 3.1

$ 8.4

$ 66.9