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PROPERTY, PLANT AND EQUIPMENT AND JOINTLY-OWNED PROJECTS: Property, Plant and Equipment Level 3 (Tables) | 12 Months Ended
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Dec. 31, 2025
Public Utility, Property, Plant and Equipment |
Schedule of Public Utility Property, Plant, and Equipment | 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.
Schedule of Jointly Owned Utility Plants | 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.

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition Tabular disclosure of proportionate interests in jointly owned utility plants. Includes the amount of plants in service, the accumulated provision for depreciation (if available), the amount of plants under construction, and the proportionate share. The amounts presented may be further subdivided to show amounts applicable to plant subcategories (for example, production, transmission, distribution). Includes statements that the amounts represent the utility's share in each joint plant and that it must provide its own financing. Information concerning two or more generating plants on the same site may be combined. States that the utility's share of direct expenses of the joint plants is included in the corresponding operating expenses on its income statement (for example, fuel, maintenance of plant, other operating expense). If the share of direct expenses is charged to purchased power, then disclose the amount so charged and the proportionate amounts charged to specific operating expenses on the records maintained for the joint plants. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 980 -SubTopic 360 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 10.C) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479070/980-360-S99-1 + Details
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- Definition Tabular disclosure of public utility physical assets used in the normal conduct of business and not intended for resale. Includes, but is not limited to, balances by class of assets, depreciation expense and method used, including composite depreciation, and accumulated depreciation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 980 -SubTopic 20 -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481834/980-20-45-1 + Details
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