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v3.23.1

Regulatory Matters (Tables) | 3 Months Ended
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Mar. 31, 2023
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, 2023 and December 31, 2022 and the period we expect to recover or refund such amounts:
| Period of |  | March 31, 2023 |  | December 31, 2022
(in thousands) | Recovery/Refund |  | Current |  | Long-Term |  | Current |  | Long Term
Regulatory Assets |  |  |  |  |  |  |  |  |
Pension and Other Postretirement Benefit Plans 1 | See Below |  | $ | — |  |  | $ | 89,474 |  |  | $ | — |  |  | $ | 88,354 |
Alternative Revenue Program Riders 2 | Up to 2 years |  | 3,705 |  |  | 3,272 |  |  | 5,679 |  |  | 2,508 |
Asset Retirement Obligations 1 | Asset lives |  | — |  |  | 1,670 |  |  | — |  |  | 1,467 |
Deferred Income Taxes | Asset lives |  | — |  |  | 729 |  |  | — |  |  | — |
ISO Cost Recovery Trackers 1 | Up to 2 years |  | 432 |  |  | 201 |  |  | 575 |  |  | 314 |
Unrecovered Project Costs 1 | Up to 5 years |  | 319 |  |  | 916 |  |  | 320 |  |  | 990 |
Deferred Rate Case Expenses 1 | Up to 3 years |  | 377 |  |  | 660 |  |  | 377 |  |  | 754 |
Fuel Clause Adjustments 1 | Up to 1 year |  | 11,361 |  |  | — |  |  | 10,893 |  |  | — |
Derivative Instruments 1 | Up to 1 year |  | 347 |  |  | — |  |  | 7,130 |  |  | — |
Other 1 | Various |  | 25 |  |  | 257 |  |  | 25 |  |  | 268 |
Total Regulatory Assets |  |  | $ | 16,566 |  |  | $ | 97,179 |  |  | $ | 24,999 |  |  | $ | 94,655 |
Regulatory Liabilities |  |  |  |  |  |  |  |  |
Deferred Income Taxes | Asset lives |  | $ | — |  |  | $ | 130,429 |  |  | $ | — |  |  | $ | 131,480 |
Plant Removal Obligations | Asset lives |  | 8,492 |  |  | 106,181 |  |  | 8,509 |  |  | 105,733 |
Fuel Clause Adjustments | Up to 1 year |  | 3,654 |  |  | — |  |  | 365 |  |  | — |
Alternative Revenue Program Riders | Up to 1 year |  | 2,326 |  |  | — |  |  | 2,504 |  |  | — |
North Dakota PTC Refunds | Asset lives |  | — |  |  | 8,254 |  |  | — |  |  | 7,136 |
Pension and Other Postretirement Benefit Plans | Up to 1 year |  | 5,589 |  |  | — |  |  | 5,589 |  |  | — |
Other | Various |  | 465 |  |  | 207 |  |  | 333 |  |  | 148 |
Total Regulatory Liabilities |  |  | $ | 20,526 |  |  | $ | 245,071 |  |  | $ | 17,300 |  |  | $ | 244,497 |
1 Costs subject to recovery without a rate of return. |  |  |  |  |  |  |  |  |
2 Amount eligible for recovery includes an incentive or rate of return. |  |  |  |  |  |  |  |  |

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