REGULATORY ASSETS AND LIABILITIES (Tables)

6 Months Ended

Jun. 30, 2025

Regulatory Assets and Liabilities Disclosure [Abstract]

Schedule of regulatory assets

(in millions)	June 30, 2025		December 31, 2024
Regulatory assets
Plant retirement related items	$	134.2	$	143.6
Environmental remediation costs	109.5		114.0
Income tax related items	57.3		55.1
AROs	35.6		27.5
Pension and OPEB costs	32.6		45.6
Bluewater Natural Gas Holding, LLC	11.5		13.4
Reactive power	10.0		13.4
Electric transmission costs	8.7		0.4
Finance and operating leases	8.6		7.5
Uncollectible expense	5.4		9.7
Other, net	18.8		19.5
Total regulatory assets	$	432.2	$	449.7

Schedule of regulatory liabilities

(in millions)	June 30, 2025		December 31, 2024
Regulatory liabilities
Income tax related items	$	314.2	$	322.0
Removal costs	210.7		206.6
Pension and OPEB benefits	86.0		88.6
Energy costs refundable through rate adjustments	61.6		49.2
Derivatives	13.4		8.0
Other, net	22.3		22.2
Total regulatory liabilities	$	708.2	$	696.6
Balance sheet presentation
Other current liabilities	$	9.4	$	0.3
Regulatory liabilities	698.8		696.3
Total regulatory liabilities	$	708.2	$	696.6