Financial Instruments and Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2025

Fair Value Disclosures [Abstract]

Gains (losses) recognized related to equity investments

	Nine Months Ended
	September 30,
	2025		2024
Net losses recognized during the period on equity securities	$	(10.1)	$	(8.5)
Less: Net gains (losses) recognized during the period on equity securities sold during the period	—		—
Unrealized losses recognized during the reporting period on equity securities still held at the reporting date	$	(10.1)	$	(8.5)

Summary Of Carrying Values And Fair Values Of Fixed Rate Debt

A summary of the aggregate carrying values and fair values of our senior unsecured notes is as follows:

	September 30, 2025		December 31, 2024
Carrying value	$	3,280.0	$	2,782.1
Fair value	$	3,192.9	$	2,578.6

Assets Measured and Recorded At Fair Value On A Nonrecurring Basis

The following table presents assets measured and recorded at fair value on a nonrecurring basis during the nine months ended September 30, 2025 and 2024:

	2025				2024
Description	Fair Value Measurements Using Significant Unobservable Inputs (Level 3)		Gain/(Loss)		Fair Value Measurements Using Significant Unobservable Inputs (Level 3)		Gain/(Loss)
Equity investment	$	—	$	—	$	48.3	$	(8.4)
Goodwill	$	75.2	$	(65.3)	$	—	$	—
Franchise rights	$	42.7	$	(71.7)	$	—	$	—
Long-lived assets held and used	$	13.5	$	(4.3)	$	—	$	(8.9)
Long-lived assets held for sale	$	22.7	$	(2.4)	$	12.1	$	(1.3)

Fair Value Measurement Inputs and Valuation Techniques

Quantitative Information about Level 3 Fair Value Measurements

Description	Fair Value at April 30, 2025		Valuation Technique	Unobservable Input	Range (Average)
Franchise rights	$	42.7	Discounted cash flow	Weighted average cost of capital	8.9% - 9.1% (9.0%)
				Discount rate	9.6% - 11.3% (10.4%)
				Long-term revenue growth rate	2.0	%
				Long-term pretax margin	0.0% - 5.9% (2.4%)
				Contributory asset charges	5.1% - 8.4% (6.2%)