FAIR VALUE MEASUREMENTS (Tables)

6 Months Ended

Jun. 30, 2025

Fair Value Disclosures [Abstract]

Schedule of fair value of assets and liabilities measured on a recurring basis categorized by level within the fair value hierarchy

The following tables summarize our financial assets and liabilities that were accounted for at fair value on a recurring basis, categorized by level within the fair value hierarchy:

	June 30, 2025
(in millions)	Level 1		Level 2		Level 3		Total
Derivative assets
Natural gas contracts	$	2.3	$	4.9	$	—	$	7.2
FTRs	—		—		6.3		6.3
Total derivative assets	$	2.3	$	4.9	$	6.3	$	13.5
Derivative liabilities
Natural gas contracts	$	1.2	$	1.1	$	—	$	2.3

	December 31, 2024
(in millions)	Level 1		Level 2		Level 3		Total
Derivative assets
Natural gas contracts	$	3.3	$	2.8	$	—	$	6.1
FTRs	—		—		2.0		2.0
Total derivative assets	$	3.3	$	2.8	$	2.0	$	8.1
Derivative liabilities
Natural gas contracts	$	0.6	$	0.3	$	—	$	0.9

Reconciliation of changes in the fair value of items categorized as level 3 measurements

The following table summarizes the changes to derivatives classified as Level 3 in the fair value hierarchy:

	Three Months Ended June 30				Six Months Ended June 30
(in millions)	2025		2024		2025		2024
Balance at the beginning of the period	$	0.4	$	0.6	$	2.0	$	2.0
Purchases	7.2		8.2		7.2		8.2
Settlements	(1.3)		(2.0)		(2.9)		(3.4)
Balance at the end of the period	$	6.3	$	6.8	$	6.3	$	6.8

Schedule of carrying value and fair value of financial instruments not recorded at fair value

The following table shows the financial instruments included on our balance sheets that were not recorded at fair value:

	June 30, 2025				December 31, 2024
(in millions)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt, including current portion	$	2,258.5	$	1,906.1	$	2,258.0	$	1,882.1