v3.26.1
Regulatory Matters (Tables)
 3 Months Ended
Mar. 31, 2026
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 March 31, 2026 and December 31, 2025 and the period we expect to recover or refund such amounts:
Period ofMarch 31, 2026December 31, 2025
(in thousands)Recovery/RefundCurrentLong-TermCurrentLong-Term
Regulatory Assets
Pension and Other Postretirement Benefit Plans1
Various$2,765 $72,864 $2,765 $72,762 
Alternative Revenue Program Riders2
Up to 2 years
9,972 3,065 7,834 1,036 
Deferred Income Taxes1
Asset lives— 8,761 — 9,007 
Fuel Clause Adjustments1
Up to 1 year
11,019 — 6,558 — 
Derivative Instruments1
Up to 2 years
862 563 2,717 — 
Other1
Various813 1,689 563 3,257 
Total Regulatory Assets$25,431 $86,942 $20,437 $86,062 
Regulatory Liabilities
Deferred Income TaxesAsset lives$— $124,156 $— $125,413 
Plant Removal ObligationsAsset lives— 131,795 — 130,686 
Fuel Clause Adjustments
Up to 1 year
2,238 — 1,231 — 
Alternative Revenue Program Riders
Up to 1 year
10,405 — 9,961 — 
North Dakota PTC RefundsAsset lives— 33,127 — 29,169 
Pension and Other Postretirement Benefit PlansVarious3,174 9,862 3,174 9,187 
OtherVarious3,285 3,135 2,234 2,943 
Total Regulatory Liabilities$19,102 $302,075 $16,600 $297,398 
1Costs subject to recovery without a rate of return.
2Amounts eligible for recovery include an incentive or rate of return.