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BENEFIT PLANS: Benefit Plans Level 3 (Tables) | 12 Months Ended
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Dec. 31, 2025
Defined Benefit Plan Disclosure |
Schedule of Accumulated Other Comprehensive Income (Loss) | The table below presents changes in components of AOCI, net of tax, during the years ended December 31 (in thousands of dollars). Items in parentheses indicate reductions to AOCI.
|  | 2025 |  | 2024 |  | 2023
Defined benefit pension items |  |  |  |  |  |
Balance at beginning of period |  | $ | (13,592) |  |  | $ | (17,184) |  |  | $ | (12,922) |
Other comprehensive income before reclassifications, net of tax of $(374), $851, and $(1,680) |  | (2,034) |  |  | 2,454 |  |  | (4,848) |
Amounts reclassified out of AOCI to net income, net of tax of $229, $394, and $203 |  | 682 |  |  | 1,138 |  |  | 586 |
Net current-period other comprehensive income |  | (1,352) |  |  | 3,592 |  |  | (4,262) |
Balance at end of period |  | $ | (14,944) |  |  | $ | (13,592) |  |  | $ | (17,184) |
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis | The following table presents information about IDACORP’s and Idaho Power’s assets and liabilities measured at fair value on a recurring basis as of December 31 (in thousands of dollars):
|  | 2025 |  | 2024
|  | Level 1 |  | Level 2 |  | Level 3 |  | Total |  | Level 1 |  | Level 2 |  | Level 3 |  | Total
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Money market funds and commercial paper |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
IDACORP(1) |  | $ | 62,012 |  |  | $ | — |  |  | $ | — |  |  | $ | 62,012 |  |  | $ | 146,308 |  |  | $ | — |  |  | $ | — |  |  | $ | 146,308 |
Idaho Power |  | 110,602 |  |  | — |  |  | — |  |  | 110,602 |  |  | 158,999 |  |  | — |  |  | — |  |  | 158,999 |
Derivatives |  | — |  |  | 3 |  |  | — |  |  | 3 |  |  | — |  |  | — |  |  | — |  |  | — |
Equity securities |  | 38,448 |  |  | — |  |  | — |  |  | 38,448 |  |  | 39,772 |  |  | — |  |  | — |  |  | 39,772 |
IDACORP assets measured at NAV (not subject to hierarchy disclosure)(1) |  | — |  |  | — |  |  | — |  |  | 5,948 |  |  | — |  |  | — |  |  | — |  |  | 4,099 |
Liabilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivatives |  | $ | 8,186 |  |  | $ | 11,533 |  |  | $ | — |  |  | $ | 19,719 |  |  | $ | 4,003 |  |  | $ | 12,256 |  |  | $ | — |  |  | $ | 16,259 |
(1) Holding company only. Does not include amounts held by Idaho Power.
Benefit Obligations [Member] |
Defined Benefit Plan Disclosure |
Schedule of Assumptions Used | The following table sets forth the weighted-average assumptions used at the end of each year to determine benefit obligations for all Idaho Power-sponsored pension and postretirement benefits plans:
|  | Pension Plan |  | SMSP |  | Postretirement Benefits
|  | 2025 |  | 2024 |  | 2025 |  | 2024 |  | 2025 |  | 2024
Discount rate |  | 5.75 | % |  | 5.70 | % |  | 5.65 | % |  | 5.70 | % |  | 5.60 | % |  | 5.70 | %
Rate of compensation increase(1) |  | 4.42 | % |  | 4.43 | % |  | 4.75 | % |  | 4.75 | % |  | — |  |  | — |
Medical trend rate |  | — |  |  | — |  |  | — |  |  | — |  |  | 7.0 | % |  | 6.3 | %
Dental trend rate |  | — |  |  | — |  |  | — |  |  | — |  |  | 4.0 | % |  | 3.5 | %
Measurement date |  | 12/31/2025 |  | 12/31/2024 |  | 12/31/2025 |  | 12/31/2024 |  | 12/31/2025 |  | 12/31/2024
(1) The 2025 rate of compensation increase assumption for the pension plan includes an inflation component of 2.40% plus a 2.02% composite merit increase component that is based on employees' years of service. Merit salary increases are assumed to be 10.6% for employees in their first year of service and scale down to 3.4% for employees in their fortieth year of service and beyond.
Net Periodic Benefit Cost [Member] |
Defined Benefit Plan Disclosure |
Schedule of Assumptions Used | The following table sets forth the weighted-average assumptions used to determine net periodic benefit cost for all Idaho Power-sponsored pension and postretirement benefit plans:
|  | Pension Plan |  | SMSP |  | Postretirement Benefits
|  | 2025 |  | 2024 |  | 2023 |  | 2025 |  | 2024 |  | 2023 |  | 2025 |  | 2024 |  | 2023
Discount rate |  | 5.70 | % |  | 5.10 | % |  | 5.45 | % |  | 5.70 | % |  | 5.20 | % |  | 5.50 | % |  | 5.70 | % |  | 5.15 | % |  | 5.45 | %
Expected long-term rate of return on assets |  | 7.40 | % |  | 7.40 | % |  | 7.40 | % |  | — |  |  | — |  |  | — |  |  | 6.00 | % |  | 6.00 | % |  | 6.00 | %
Rate of compensation increase |  | 4.42 | % |  | 4.43 | % |  | 4.49 | % |  | 4.75 | % |  | 4.75 | % |  | 4.75 | % |  | — |  |  | — | % |  | — | %
Medical trend rate |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 6.2 | % |  | 7.1 | % |  | 6.7 | %
Dental trend rate |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 4.0 | % |  | 3.5 | % |  | 3.5 | %
Pension Plan |
Defined Benefit Plan Disclosure |
Schedule of Defined Benefit Plans Disclosures | The following table summarizes the changes in benefit obligations and plan assets of these plans (in thousands of dollars):
|  | Pension Plan |  | SMSP
|  | 2025 |  | 2024 |  | 2025 |  | 2024
Change in projected benefit obligation: |  |  |  |  |  |  |  |
Benefit obligation at January 1 |  | $ | 998,166 |  |  | $ | 1,028,016 |  |  | $ | 102,318 |  |  | $ | 105,809 |
Service cost |  | 31,774 |  |  | 33,992 |  |  | 1,172 |  |  | 1,051 |
Interest cost |  | 56,151 |  |  | 52,181 |  |  | 5,640 |  |  | 5,332 |
Actuarial loss (gain) |  | 5,237 |  |  | (65,972) |  |  | 2,401 |  |  | (3,321) |
Plan amendment |  | — |  |  | — |  |  | 7 |  |  | 15 |
Benefits paid |  | (52,309) |  |  | (50,051) |  |  | (6,900) |  |  | (6,568) |
Projected benefit obligation at December 31 |  | 1,039,019 |  |  | 998,166 |  |  | 104,638 |  |  | 102,318 |
Change in plan assets: |  |  |  |  |  |  |  |
Fair value at January 1 |  | 951,142 |  |  | 917,513 |  |  | — |  |  | — |
Actual return on plan assets |  | 104,542 |  |  | 63,680 |  |  | — |  |  | — |
Employer contributions |  | 20,000 |  |  | 20,000 |  |  | — |  |  | — |
Benefits paid |  | (52,309) |  |  | (50,051) |  |  | — |  |  | — |
Fair value at December 31 |  | 1,023,375 |  |  | 951,142 |  |  | — |  |  | — |
Funded status at end of year |  | $ | (15,644) |  |  | $ | (47,024) |  |  | $ | (104,638) |  |  | $ | (102,318) |
Amounts recognized in the balance sheet consist of: |  |  |  |  |  |  |  |
Other current liabilities |  | $ | — |  |  | $ | — |  |  | $ | (6,855) |  |  | $ | (6,827) |
Noncurrent liabilities |  | (15,644) |  |  | (47,024) |  |  | (97,783) |  |  | (95,491) |
Net amount recognized |  | $ | (15,644) |  |  | $ | (47,024) |  |  | $ | (104,638) |  |  | $ | (102,318) |
Amounts recognized in AOCI consist of: |  |  |  |  |  |  |  |
Net loss |  | $ | 13,142 |  |  | $ | 43,516 |  |  | $ | 18,154 |  |  | $ | 16,442 |
Prior service cost |  | 18 |  |  | 24 |  |  | 1,780 |  |  | 1,995 |
Subtotal |  | 13,160 |  |  | 43,540 |  |  | 19,934 |  |  | 18,437 |
Less amount recorded as regulatory asset(1) |  | (13,160) |  |  | (43,540) |  |  | — |  |  | — |
Net amount recognized in AOCI |  | $ | — |  |  | $ | — |  |  | $ | 19,934 |  |  | $ | 18,437 |
Accumulated benefit obligation |  | $ | 895,190 |  |  | $ | 863,705 |  |  | $ | 99,105 |  |  | $ | 96,487 |
(1) Changes in the funded status of the pension plan that would be recorded in AOCI for an unregulated entity are recorded as a regulatory asset for Idaho Power as Idaho Power believes it is probable that an amount equal to the regulatory asset will be collected through the setting of future rates.
Schedule of Costs of Retirement Plans | The following table shows the components of net periodic pension cost for these plans (in thousands of dollars). For purposes of calculating the expected return on plan assets, the market-related value of assets is equal to the fair value of the assets.
|  | Pension Plan |  | SMSP
|  | 2025 |  | 2024 |  | 2023 |  | 2025 |  | 2024 |  | 2023
Service cost |  | $ | 31,774 |  |  | $ | 33,992 |  |  | $ | 29,843 |  |  | $ | 1,172 |  |  | $ | 1,051 |  |  | $ | 612 |
Interest cost |  | 56,151 |  |  | 52,181 |  |  | 51,277 |  |  | 5,640 |  |  | 5,332 |  |  | 5,322 |
Expected return on assets |  | (68,931) |  |  | (66,533) |  |  | (61,728) |  |  | — |  |  | — |  |  | — |
Amortization of net loss |  | — |  |  | 1,700 |  |  | — |  |  | 690 |  |  | 1,312 |  |  | 570 |
Amortization of prior service cost |  | 6 |  |  | 6 |  |  | 6 |  |  | 221 |  |  | 220 |  |  | 219 |
Net periodic pension cost |  | 19,000 |  |  | 21,346 |  |  | 19,398 |  |  | 7,723 |  |  | 7,915 |  |  | 6,723 |
Regulatory deferral of net periodic pension cost(1) |  | (18,159) |  |  | (20,425) |  |  | (18,553) |  |  | — |  |  | — |  |  | — |
Previously deferred pension cost recognized(1) |  | 35,182 |  |  | 35,182 |  |  | 17,154 |  |  | — |  |  | — |  |  | — |
Net periodic pension cost recognized for financial reporting(1)(2) |  | $ | 36,023 |  |  | $ | 36,103 |  |  | $ | 17,999 |  |  | $ | 7,723 |  |  | $ | 7,915 |  |  | $ | 6,723 |
(1) Net periodic pension costs for the pension plan are recognized for financial reporting based upon the authorization of each regulatory jurisdiction in which Idaho Power operates. Under an IPUC order, the Idaho portion of net periodic pension cost is recorded as a regulatory asset and is recognized in the income statement as those costs are recovered through rates. (2) Of total net periodic pension cost recognized for financial reporting $37.8 million, $35.9 million, and $18.2 million respectively, was recognized in "Other operations and maintenance" and $6.0 million, $8.1 million, and $6.5 million respectively, was recognized in "Other income, net" on the consolidated statements of income of the companies for the twelve months ended December 31, 2025, 2024, and 2023.
Schedule of Amounts Recognized in Other Comprehensive Income (Loss) | The following table shows the components of other comprehensive income (loss) for the plans (in thousands of dollars):
|  | Pension Plan |  | SMSP
|  | 2025 |  | 2024 |  | 2023 |  | 2025 |  | 2024 |  | 2023
Actuarial gain (loss) during the year |  | $ | 30,374 |  |  | $ | 63,119 |  |  | $ | (25,071) |  |  | $ | (2,401) |  |  | $ | 3,320 |  |  | $ | (6,517) |
Plan amendment service cost |  | — |  |  | — |  |  | — |  |  | (7) |  |  | (15) |  |  | (11) |
Reclassification adjustments for: |  |  |  |  |  |  |  |  |  |  |  |
Amortization of net loss |  | — |  |  | 1,700 |  |  | — |  |  | 690 |  |  | 1,312 |  |  | 570 |
Amortization of prior service cost |  | 6 |  |  | 6 |  |  | 6 |  |  | 221 |  |  | 220 |  |  | 219 |
Adjustment for deferred tax effects |  | (7,604) |  |  | (16,686) |  |  | 6,452 |  |  | 145 |  |  | (1,245) |  |  | 1,477 |
Adjustment due to the effects of regulation |  | (22,776) |  |  | (48,139) |  |  | 18,613 |  |  | — |  |  | — |  |  | — |
Other comprehensive income (loss) recognized related to pension benefit plans |  | $ | — |  |  | $ | — |  |  | $ | — |  |  | $ | (1,352) |  |  | $ | 3,592 |  |  | $ | (4,262) |
Schedule of Expected Benefit Payments | The following table summarizes the expected future benefit payments of these plans (in thousands of dollars):
|  | 2026 |  | 2027 |  | 2028 |  | 2029 |  | 2030 |  | 2031-2035
Pension Plan |  | $ | 53,000 |  |  | $ | 54,713 |  |  | $ | 56,371 |  |  | $ | 58,110 |  |  | $ | 59,898 |  |  | $ | 331,936 |
SMSP |  | 6,855 |  |  | 6,883 |  |  | 7,079 |  |  | 7,360 |  |  | 7,438 |  |  | 37,939 |
Schedule of Allocation of Plan Assets | Pension Asset Allocation Policy: The target allocation and actual allocations at December 31, 2025, for the pension asset portfolio by asset class is set forth below:
Asset Class |  | Target Allocation |  | Actual Allocation December 31, 2025
Debt securities |  | 25 | % |  | 25 | %
Equity securities |  | 56 | % |  | 59 | %
Real estate |  | 8 | % |  | 8 | %
Other plan assets |  | 11 | % |  | 8 | %
Total |  | 100 | % |  | 100 | %
Postretirement Benefits |
Defined Benefit Plan Disclosure |
Schedule of Amounts Recognized in Other Comprehensive Income (Loss) | The following table shows the components of other comprehensive income for the plan (in thousands of dollars):
|  | 2025 |  | 2024 |  | 2023
Actuarial gain during the year |  | $ | 619 |  |  | $ | 3,616 |  |  | $ | 7,572 |
Reclassification adjustments for: |  |  |  |  |  |
Amortization of net loss |  | (1,765) |  |  | (1,494) |  |  | (1,237) |
Amortization of prior service cost |  | 1,375 |  |  | 1,548 |  |  | 1,665 |
Adjustment for deferred tax effects |  | (57) |  |  | (945) |  |  | (2,059) |
Adjustment due to the effects of regulation |  | (172) |  |  | (2,725) |  |  | (5,941) |
Other comprehensive income related to postretirement benefit plans |  | $ | — |  |  | $ | — |  |  | $ | — |
Schedule of Changes in Projected Benefit Obligations | The following table summarizes the changes in benefit obligation and plan assets (in thousands of dollars):
|  | 2025 |  | 2024
Change in accumulated benefit obligation: |  |  |  |
Benefit obligation at January 1 |  | $ | 54,604 |  |  | $ | 56,064 |
Service cost |  | 672 |  |  | 698 |
Interest cost |  | 2,973 |  |  | 2,824 |
Actuarial loss (gain) |  | 1,976 |  |  | (778) |
Benefits paid(1) |  | (4,714) |  |  | (4,204) |
Benefit obligation at December 31 |  | 55,511 |  |  | 54,604 |
Change in plan assets: |  |  |  |
Fair value of plan assets at January 1 |  | 31,128 |  |  | 31,804 |
Actual return on plan assets |  | 4,381 |  |  | 4,669 |
Employer contributions(1) |  | 736 |  |  | (1,141) |
Benefits paid(1) |  | (4,714) |  |  | (4,204) |
Fair value of plan assets at December 31 |  | 31,531 |  |  | 31,128 |
Funded status at end of year (included in noncurrent liabilities) |  | $ | (23,980) |  |  | $ | (23,476) |
(1) Contributions and benefits paid are each net of $2.3 million and $2.3 million of plan participant contributions for 2025 and 2024, respectively.
Schedule of Accumulated Other Comprehensive Income (Loss) | Amounts recognized in AOCI consist of the following (in thousands of dollars):
|  | 2025 |  | 2024
Net gain |  | $ | (28,207) |  |  | $ | (29,353) |
Prior service cost |  | 3,262 |  |  | 4,636 |
Subtotal |  | (24,945) |  |  | (24,717) |
Less amount recognized in regulatory assets |  | 24,945 |  |  | 24,717 |
Net amount recognized in AOCI |  | $ | — |  |  | $ | — |
Schedule of Net Benefit Costs | The net periodic postretirement benefit cost was as follows (in thousands of dollars):
|  | 2025 |  | 2024 |  | 2023
Service cost |  | $ | 672 |  |  | $ | 698 |  |  | $ | 658 |
Interest cost |  | 2,973 |  |  | 2,824 |  |  | 2,980 |
Expected return on plan assets |  | (1,786) |  |  | (1,831) |  |  | (1,650) |
Amortization of net loss |  | (1,765) |  |  | (1,494) |  |  | (1,237) |
Amortization of prior service cost |  | 1,374 |  |  | 1,548 |  |  | 1,665 |
Net periodic postretirement benefit cost |  | $ | 1,468 |  |  | $ | 1,745 |  |  | $ | 2,416 |
Schedule of Expected Benefit Payments | The following table summarizes the expected future benefit payments of the postretirement benefit plan (in thousands of dollars):
|  | 2026 |  | 2027 |  | 2028 |  | 2029 |  | 2030 |  | 2031-2035
Expected benefit payments |  | $ | 4,855 |  |  | $ | 4,715 |  |  | $ | 4,620 |  |  | $ | 4,580 |  |  | $ | 4,511 |  |  | $ | 21,157 |
Other Pension Plan [Member] |
Defined Benefit Plan Disclosure |
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis | The following table presents the fair value of the plans' investments by asset category (in thousands of dollars).
|  | Level 1 |  | Level 2 |  | Level 3 |  | Total
Assets at December 31, 2025 |  |  |  |  |  |  |  |
Cash and cash equivalents |  | $ | 11,625 |  |  | $ | — |  |  | $ | — |  |  | $ | 11,625 |
Intermediate bonds |  | 42,326 |  |  | 204,129 |  |  | — |  |  | 246,455 |
Equity Securities: Large-Cap |  | 54,168 |  |  | — |  |  | — |  |  | 54,168 |
Equity Securities: Mid-Cap |  | 106,437 |  |  | — |  |  | — |  |  | 106,437 |
Equity Securities: Small-Cap |  | 85,047 |  |  | — |  |  | — |  |  | 85,047 |
Equity Securities: Micro-Cap |  | 43,752 |  |  | — |  |  | — |  |  | 43,752 |
Equity Securities: Global and International |  | 63,998 |  |  | — |  |  | — |  |  | 63,998 |
Equity Securities: Emerging Markets |  | 3,433 |  |  | — |  |  | — |  |  | 3,433 |
Plan assets measured at NAV (not subject to hierarchy disclosure) |  |  |  |  |  |  |  |
Commingled Fund: Equity Securities: Large-Cap |  |  |  |  |  |  |  | 52,830 |
Commingled Fund: Equity Securities: Global and International |  |  |  |  |  |  |  | 146,047 |
Commingled Fund: Equity Securities: Emerging Markets |  |  |  |  |  |  |  | 52,305 |
Direct Lending Fund: Fixed Income |  |  |  |  |  |  |  | 8,377 |
Real estate |  |  |  |  |  |  |  | 77,141 |
Other Private market investments |  |  |  |  |  |  |  | 71,760 |
Total |  | $ | 410,786 |  |  | $ | 204,129 |  |  | $ | — |  |  | $ | 1,023,375 |
Postretirement plan assets(1) |  | $ | 1,224 |  |  | $ | 30,307 |  |  | $ | — |  |  | $ | 31,531 |
|  | Level 1 |  | Level 2 |  | Level 3 |  | Total
Assets at December 31, 2024 |  |  |  |  |  |  |  |
Cash and cash equivalents |  | $ | 24,946 |  |  | $ | — |  |  | $ | — |  |  | $ | 24,946 |
Intermediate bonds |  | 40,177 |  |  | 184,528 |  |  | — |  |  | 224,705 |
Equity Securities: Large-Cap |  | 49,848 |  |  | — |  |  | — |  |  | 49,848 |
Equity Securities: Mid-Cap |  | 103,117 |  |  | — |  |  | — |  |  | 103,117 |
Equity Securities: Small-Cap |  | 82,932 |  |  | — |  |  | — |  |  | 82,932 |
Equity Securities: Micro-Cap |  | 38,871 |  |  | — |  |  | — |  |  | 38,871 |
Equity Securities: Global and International |  | 58,767 |  |  | — |  |  | — |  |  | 58,767 |
Equity Securities: Emerging Markets |  | 6,093 |  |  | — |  |  | — |  |  | 6,093 |
Plan assets measured at NAV (not subject to hierarchy disclosure) |  |  |  |  |  |  |  |
Commingled Fund: Equity Securities: Large-Cap |  |  |  |  |  |  |  | 54,346 |
Commingled Fund: Equity Securities: Global and International |  |  |  |  |  |  |  | 124,559 |
Commingled Fund: Equity Securities: Emerging Markets |  |  |  |  |  |  |  | 41,590 |
Direct Lending Fund: Fixed Income |  |  |  |  |  |  |  | 5,479 |
Real estate |  |  |  |  |  |  |  | 72,913 |
Other Private market investments |  |  |  |  |  |  |  | 62,976 |
Total |  | $ | 404,751 |  |  | $ | 184,528 |  |  | $ | — |  |  | $ | 951,142 |
Postretirement plan assets(1) |  | $ | 3,054 |  |  | $ | 28,074 |  |  | $ | — |  |  | $ | 31,128 |
(1) The postretirement benefits assets are primarily life insurance contracts.

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