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PROPERTY, PLANT AND EQUIPMENT AND JOINTLY-OWNED PROJECTS: | 12 Months Ended
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Dec. 31, 2025
Property, Plant and Equipment [Abstract] |
Property, Plant and Equipment Disclosure | PROPERTY, PLANT AND EQUIPMENT AND JOINTLY-OWNED PROJECTS The following table presents the major classifications of Idaho Power’s utility plant in service, annual depreciation provisions as a percent of average depreciable balance, and accumulated provision for depreciation for the years ended December 31 (in thousands of dollars):
|  | 2025 |  | 2024
|  | Balance |  | Avg Rate |  | Balance |  | Avg Rate
Production |  | $ | 2,675,671 |  |  | 4.02 | % |  | $ | 2,858,678 |  |  | 3.90 | %
Transmission |  | 1,653,490 |  |  | 1.91 | % |  | 1,534,474 |  |  | 1.89 | %
Energy Storage(1) |  | 509,740 |  |  | 5.06 | % |  | 393,012 |  |  | 3.61 | %
Distribution(1) |  | 2,658,849 |  |  | 2.17 | % |  | 2,465,423 |  |  | 2.16 | %
General and Other |  | 751,356 |  |  | 5.27 | % |  | 706,176 |  |  | 5.18 | %
Total in service |  | 8,249,106 |  |  | 3.18 | % |  | 7,957,763 |  |  | 3.06 | %
Accumulated provision for depreciation |  | (2,599,465) |  |  |  |  | (2,714,706) |  |  |
In service - net |  | $ | 5,649,641 |  |  |  |  | $ | 5,243,057 |  |  |
(1) The presentation of the major classifications of Idaho Power's utility plant in service in the table above has been modified to separately report the energy storage balance for the years ended December 31, 2025 and 2024. The prior year energy storage balance, which had previously been classified in the distribution balance, has been reclassified to conform with the current year presentation. This change reflects a shift from one acceptable presentation to another to enhance transparency. At December 31, 2025, Idaho Power's construction work in progress balance of $1.7 billion included relicensing costs of $536.1 million for the HCC, Idaho Power's largest hydropower complex. The IPUC allows Idaho Power to collect a portion of AFUDC relating to the HCC relicensing project in its Idaho jurisdiction rates. For more information, refer to Note 3 - "Regulatory Matters." Collecting these amounts will reduce the amount collected in the future once the HCC relicensing costs are approved for recovery in base rates. At December 31, 2025, Idaho Power's regulatory liability for collection of AFUDC relating to the HCC was $281.0 million. Idaho Power's ownership interest in two jointly-owned generating facilities is included in the table above. Under the joint operating agreements for these facilities, each participating utility is responsible for financing its share of construction, operating, and leasing costs. Idaho Power's proportionate share of operating expenses for each facility is included in the Consolidated Statements of Income. These jointly-owned facilities, including balance sheet amounts and the extent of Idaho Power’s participation, were as follows at December 31, 2025 (in thousands of dollars):
Name of Plant |  | Location |  | Utility Plant in Service |  | Construction Work in Progress |  | Accumulated Provision for Depreciation |  | Ownership % |  | MW(1)(2)
Jim Bridger units 1-4 |  | Rock Springs, WY |  | $ | 777,096 |  |  | $ | 780 |  |  | $ | 575,151 |  |  | 33 |  | 775
North Valmy units 1 & 2(2) |  | Winnemucca, NV |  | 42,113 |  |  | 21,118 |  |  | (128) |  |  | 50 |  | 284
(1) Idaho Power’s share of nameplate capacity. (2) Pursuant to an agreement with NV Energy, Idaho Power ceased participation in coal-fired operations of North Valmy in December 2019 at unit 1 and December 2025 at unit 2. Idaho Power's 2025 IRP identified a preferred resource portfolio and action plan that includes the conversion of the two generating units at the North Valmy plant from coal to natural gas by mid-2026. The conversion of Unit 1 has been completed and the unit was placed in-service in December 2025, and conversion of Unit 2 is expected to be completed by mid-2026. IERCo, Idaho Power’s wholly-owned subsidiary, is a joint-owner of BCC. Idaho Power’s coal purchases from BCC were $54.4 million in 2025, $51.6 million in 2024, and $67.9 million in 2023.

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