Other Comprehensive Income (Tables)

12 Months Ended

Dec. 31, 2025

Statement of Comprehensive Income [Abstract]

Reclassification out of Accumulated Other Comprehensive Income

The following table details reclassifications out of AOCI and into Net income. The amounts in parentheses below indicate decreases to Net income in the Consolidated Statements of Income for the period, net of tax:


	Location on the Consolidated	Amount Reclassified from AOCI
	Statements of Income	December 31, 2025			December 31, 2024
		(in millions)
Gains and (losses) on cash flow hedges:
Interest rate swaps	Interest expense	$	(2.9	)	$	(2.9	)
Commodity contracts	Fuel, purchased power, and cost of natural gas sold		(1.0	)		(3.5	)
			(3.9	)		(6.4	)
Income tax	Income tax benefit (expense)		0.9			1.4
Total reclassification adjustments related to cash flow hedges, net of tax		$	(3.0	)	$	(5.0	)

Amortization of components of defined benefit plans:
Prior service cost	Operations and maintenance	$	—		$	—

Actuarial gain (loss)	Operations and maintenance		0.8			(0.2	)
			0.8			(0.2	)
Income tax	Income tax benefit (expense)		(0.2	)		0.1
Total reclassification adjustments related to defined benefit plans, net of tax		$	0.6		$	(0.1	)

Total reclassifications		$	(2.4	)	$	(5.1	)

Schedule of Accumulated Other Comprehensive Income (Loss)

Balances by classification included within AOCI, net of tax on the accompanying Consolidated Balance Sheets were as follows:


	Derivatives Designated as Cash Flow Hedges
	Interest Rate Swaps			Commodity Derivatives			Employee Benefit Plans			Total
	(in millions)
As of December 31, 2023	$	(6.1	)	$	(2.5	)	$	(6.2	)	$	(14.8	)
Other comprehensive income (loss)
before reclassifications		—			(0.5	)		0.8			0.3
Amounts reclassified from AOCI		2.3			2.7			0.1			5.1
As of December 31, 2024	$	(3.8	)	$	(0.3	)	$	(5.3	)	$	(9.4	)
Other comprehensive income (loss)
before reclassifications		—			(2.7	)		—			(2.7	)
Amounts reclassified from AOCI		2.2			0.8			(0.6	)		2.4
As of December 31, 2025	$	(1.6	)	$	(2.2	)	$	(5.9	)	$	(9.7	)