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v3.25.1

Regulatory Matters (Tables) | 3 Months Ended
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Mar. 31, 2025
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, 2025 and December 31, 2024 and the period we expect to recover or refund such amounts:
| Period of |  | March 31, 2025 |  | December 31, 2024
(in thousands) | Recovery/Refund |  | Current |  | Long-Term |  | Current |  | Long-Term
Regulatory Assets |  |  |  |  |  |  |  |  |
Pension and Other Postretirement Benefit Plans 1 | Various |  | $ | — |  |  | $ | 87,834 |  |  | $ | — |  |  | $ | 88,161 |
Alternative Revenue Program Riders 2 | Up to 2 years |  | 4,226 |  |  | 244 |  |  | 4,257 |  |  | 195 |
Deferred Income Taxes 1 | Asset lives |  | — |  |  | 9,053 |  |  | — |  |  | 8,944 |
Fuel Clause Adjustments 1 | Up to 1 year |  | 5,418 |  |  | — |  |  | 2,218 |  |  | — |
Derivative Instruments 1 | Up to 2 years |  | 632 |  |  | 1,052 |  |  | 1,989 |  |  | — |
Other 1 | Various |  | 1,263 |  |  | 1,241 |  |  | 1,498 |  |  | 1,373 |
Total Regulatory Assets |  |  | $ | 11,539 |  |  | $ | 99,424 |  |  | $ | 9,962 |  |  | $ | 98,673 |
Regulatory Liabilities |  |  |  |  |  |  |  |  |
Deferred Income Taxes | Asset lives |  | $ | — |  |  | $ | 128,495 |  |  | $ | — |  |  | $ | 130,387 |
Plant Removal Obligations | Asset lives |  | — |  |  | 126,579 |  |  | — |  |  | 126,263 |
Fuel Clause Adjustments | Up to 1 year |  | 7,169 |  |  | — |  |  | 11,432 |  |  | — |
Alternative Revenue Program Riders | Up to 1 year |  | 14,917 |  |  | — |  |  | 14,255 |  |  | — |
North Dakota PTC Refunds | Asset lives |  | — |  |  | 23,816 |  |  | — |  |  | 20,099 |
Pension and Other Postretirement Benefit Plans | Various |  | 2,547 |  |  | 10,153 |  |  | 2,547 |  |  | 10,758 |
Other | Various |  | 2,395 |  |  | 1,635 |  |  | 1,073 |  |  | 1,421 |
Total Regulatory Liabilities |  |  | $ | 27,028 |  |  | $ | 290,678 |  |  | $ | 29,307 |  |  | $ | 288,928 |
1 Costs subject to recovery without a rate of return. |  |  |  |  |  |  |  |  |
2 Amounts eligible for recovery includes an incentive or rate of return. |  |  |  |  |  |  |  |

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