XML 122 R95.htm IDEA: XBRL DOCUMENT v3.25.4
BENEFIT PLANS: Defined Benefit Plan, Net Periodic Benefit Cost (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Defined Benefit Plan Disclosure      
Net periodic benefit cost $ 5,986 $ 8,077 $ 6,513
Pension Plan      
Defined Benefit Plan Disclosure      
Service cost 31,774 33,992 29,843
Interest cost 56,151 52,181 51,277
Expected return on plan assets 68,931 66,533 61,728
Amortization of net loss 0 (1,700) 0
Amortization of prior service cost 6 6 6
Net periodic benefit cost 19,000 21,346 19,398
Regulatory deferral of net periodic benfit cost [1] 18,159 20,425 18,553
Previously deferred pension cost recognized [1] 35,182 35,182 17,154
Net periodic benefit cost recognized for financial reporting [1],[2] 36,023 36,103 17,999
Pension and SMSP      
Defined Benefit Plan Disclosure      
NetServiceCostDefinedBenefitPlan 37,800 35,900 18,200
otherexpensedefinedbenefitplanbenefitcost 6,000 8,100 6,500
Senior Management Security Plan      
Defined Benefit Plan Disclosure      
Service cost 1,172 1,051 612
Interest cost 5,640 5,332 5,322
Expected return on plan assets 0 0 0
Amortization of net loss (690) (1,312) (570)
Amortization of prior service cost 221 220 219
Net periodic benefit cost 7,723 7,915 6,723
Regulatory deferral of net periodic benfit cost 0 0 0
Net periodic benefit cost recognized for financial reporting [2] 7,723 7,915 6,723
Postretirement Benefits      
Defined Benefit Plan Disclosure      
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 benefit cost $ 1,468 $ 1,745 $ 2,416
[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.