v3.26.1
BENEFIT PLANS: Level 4 (Details)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
USD ($)
plan
Jun. 30, 2025
USD ($)
plan
Jun. 30, 2026
USD ($)
plan
Jun. 30, 2025
USD ($)
plan
Defined Benefit Plan Disclosure        
Number of plans | plan 2 2 2 2
Service cost $ 8,413 $ 8,318 $ 17,148 $ 16,637
Interest cost 16,677 16,021 33,411 32,041
Expected return on plan assets (18,981) (17,677) (37,985) (35,362)
Amortization of prior service cost 330 400 663 801
Amortization of net loss (186) (271) (364) (538)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) 6,253 6,791 12,873 13,579
Regulatory deferral of net periodic benefit cost (3,841) [1] (4,265) [1] (7,970) [2] (8,562) [2]
IPUC Authorized recovered pension cost 8,795 [1] 8,795 [1] 17,591 [2] 17,591 [2]
Net periodic benefit cost recognized for financial reporting 11,207 [1],[3] 11,321 [1],[3] 22,494 [2],[4] 22,608 [2],[4]
Net Periodic Benefit cost recognize in Other operations and maintenance 9,700 9,800 19,400 19,600
Net Periodic Benefit cost recognized in other expense, net 1,500 1,500 3,100 3,000
Pension Plan        
Defined Benefit Plan Disclosure        
Service cost 8,030 7,858 16,337 15,715
Interest cost 14,518 13,867 29,078 27,734
Expected return on plan assets (18,529) (17,234) (37,078) (34,469)
Amortization of prior service cost 1 1 3 3
Amortization of net loss 0 0 0 0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) 4,020 4,492 8,340 8,983
Regulatory deferral of net periodic benefit cost (3,841) [1] (4,265) [1] (7,970) [2] (8,562) [2]
IPUC Authorized recovered pension cost 8,795 [1] 8,795 [1] 17,591 [2] 17,591 [2]
Net periodic benefit cost recognized for financial reporting 8,974 [1],[3] 9,022 [1],[3] 17,961 [2],[4] 18,012 [2],[4]
Pension Plan | Idaho Power Company        
Defined Benefit Plan Disclosure        
Defined Benefit Plan, Contributions by Employer     0  
Defined Benefit Plan, Expected Future Benefit Payment, Remainder of Fiscal Year 30,000   30,000  
Senior Management Security Plan        
Defined Benefit Plan Disclosure        
Service cost 240 293 480 586
Interest cost 1,431 1,410 2,861 2,820
Expected return on plan assets 0 0 0 0
Amortization of prior service cost 55 56 111 111
Amortization of net loss 240 172 480 345
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) 1,966 1,931 3,932 3,862
Net periodic benefit cost recognized for financial reporting 1,966 1,931 3,932 3,862
Postretirement Benefits Plan        
Defined Benefit Plan Disclosure        
Service cost 143 167 331 336
Interest cost 728 744 1,472 1,487
Expected return on plan assets (452) (443) (907) (893)
Amortization of prior service cost 274 343 549 687
Amortization of net loss (426) (443) (844) (883)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) 267 368 601 734
Net periodic benefit cost recognized for financial reporting $ 267 $ 368 $ 601 $ 734
[1] Net periodic benefit costs for the pension plan are recognized for financial reporting based upon the authorization of each regulatory jurisdiction in which Idaho Power operates. Under IPUC order, the Idaho portion of net periodic benefit cost is recorded as a regulatory asset and is recognized in the income statement as those costs are recovered through rates.
[2] Net periodic benefit costs for the pension plan are recognized for financial reporting based upon the authorization of each regulatory jurisdiction in which Idaho Power operates. Under IPUC order, the Idaho portion of net periodic benefit cost is recorded as a regulatory asset and is recognized in the income statement as those costs are recovered through rates.
[3] Of total net periodic benefit cost recognized for financial reporting, $9.7 million and $9.8 million, respectively, were recognized in "Other operations and maintenance" and $1.5 million and $1.5 million, respectively, were recognized in "Other income, net" on the condensed consolidated statements of income of the companies for the three months ended June 30, 2026 and 2025.
[4] Of total net periodic benefit cost recognized for financial reporting, $19.4 million and $19.6 million, respectively, were recognized in "Other operations and maintenance" and $3.1 million and $3.0 million, respectively, were recognized in "Other income, net" on the condensed consolidated statements of income of the companies for the six months ended June 30, 2026 and 2025.