Regulatory Matters (Tables)

12 Months Ended

Dec. 31, 2024

Regulatory Assets and Liabilities Disclosure [Abstract]

Schedule of Regulatory Assets and Liabilities

The following presents our current and long-term regulatory assets and liabilities as of December 31, 2024 and 2023 and the period we expect to recover or refund such amounts:


	Period of	2024				2023
(in thousands)	Recovery/Refund	Current		Long-Term		Current		Long-Term

Regulatory Assets
Pension and Other Postretirement Benefit Plans1	See below	$	—	$	88,161	$	154	$	86,134
Alternative Revenue Program Riders2	Up to 2 years	4,257		195		3,719		158

Deferred Income Taxes	Asset lives	—		8,944		—		6,940
Fuel Clause Adjustments1	Up to 1 year	2,218		—		7,294		—
Derivative Instruments1	Up to 1 year	1,989		—		4,210		—
Other1	Various	1,498		1,373		750		2,483
Total Regulatory Assets		9,962		98,673		16,127		95,715
Regulatory Liabilities
Deferred Income Taxes	Asset lives	—		130,387		—		136,022
Plant Removal Obligations	Asset lives	—		126,263		—		117,030
Fuel Clause Adjustments	Up to 1 year	11,432		—		11,350		—
Alternative Revenue Program Riders	Up to 1 year	14,255		—		6,885		—
North Dakota PTC Refunds	Asset lives	—		20,099		—		12,011
Pension and Other Postretirement Benefit Plans	See below	2,547		10,758		6,138		11,307



Other	Various	1,073		1,421		1,035		177
Total Regulatory Liabilities		$	29,307	$	288,928	$	25,408	$	276,547

1Costs subject to recovery without a rate of return.
2Amount eligible for recovery includes an incentive or rate of return.