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, 2025

Sep. 30, 2024

Sep. 30, 2025

Sep. 30, 2024

Jun. 30, 2025

Dec. 31, 2024

Jun. 30, 2024

Dec. 31, 2023

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

Investments, Fair Value Disclosure

$ 844.7

$ 795.5

$ 844.7

$ 795.5

$ 742.0

$ 740.8

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

309.0

378.8

309.0

378.8

$ 293.1

$ 330.3

$ 367.8

$ 367.3

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

Business Combination, Contingent Consideration, Liability, Beginning Balance

19.1

53.7

35.8

57.5

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

19.9

31.7

93.8

10.3

Business Combination, Contingent Consideration, Liability, Ending Balance

16.1

35.2

16.1

35.2

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

14.7

25.7

14.7

25.7

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

0.4

(20.9)

(3.1)

(33.5)

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

(0.1)

0.2

0.3

0.2

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

0.0

2.4

0.2

13.4

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

(3.3)

(0.2)

(15.4)

(2.2)

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

0.0

(1.7)

(0.2)

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

3.4

17.3

20.4

45.5

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

52.9

32.8

117.8

78.9

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

(61.5)

(56.1)

(217.3)

(109.0)

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

15.4

9.5

(29.8)

(0.9)

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

(0.3)

1.5

1.8

1.2

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

0.8

0.0

6.8

2.8

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

0.0

(0.1)

0.0

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

$ 0.0

$ 8.4