v3.25.1
BENEFIT PLANS: Level 3 (Tables)
 3 Months Ended
Mar. 31, 2025
Retirement Benefits [Abstract]  
Schedule of Defined Benefit Plans Disclosures [Table Text Block] The table below shows the components of net periodic benefit costs for the pension, SMSP, and postretirement benefits plans for the three months ended March 31, 2025 and 2024 (in thousands).
Pension PlanSMSPPostretirement
Benefits		Total
 20252024202520242025202420252024
Service cost$7,857 $8,184 $293 $263 $169 $164 $8,319 $8,611 
Interest cost13,867 12,793 1,410 1,333 743 691 16,020 14,817 
Expected return on plan assets(17,235)(16,830)— — (450)(455)(17,685)(17,285)
Amortization of prior service cost2 62 55 55 344 387 401 504 
Amortization of net loss— — 173 328 (440)(395)(267)(67)
Net periodic benefit cost4,491 4,209 1,931 1,979 366 392 6,788 6,580 
Regulatory deferral of net periodic benefit cost(1)
(4,297)(4,026)— — — — (4,297)(4,026)
Previously deferred pension costs recognized(1)
8,796 8,796 — — — — 8,796 8,796 
Net periodic benefit cost recognized for financial reporting(1)(2)
$8,990 $8,979 $1,931 $1,979 $366 $392 $11,287 $11,350 
(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) Of total net periodic benefit cost recognized for financial reporting, $9.8 million and $9.4 million, respectively, were recognized in "Other operations and maintenance" and $1.5 million and $2.0 million, respectively, were recognized in "Other income, net" on the condensed consolidated statements of income of the companies for the three months ended March 31, 2025 and 2024.