v3.26.1
REGULATORY MATTERS: Level 4 (Details) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2027
May 31, 2027
Jun. 01, 2025
Jun. 01, 2024
Jan. 01, 2024
Settlement Stipulation - Investment Tax Credits and Idaho Sharing Mechanism              
Regulatory Matters              
Effective Income Tax Rate Reconciliation, Tax Credit, Investment, Amount $ 6,300 $ 19,300          
Settlement Stipulation - Investment Tax Credits and Idaho Sharing Mechanism | ADITC              
Regulatory Matters              
Investment Tax Credits, Remains Available $ 159,600            
Idaho fixed cost adjustment mechanism              
Regulatory Matters              
Percentage cap on the FCA adjustment 3.00%            
Annual fixed cost adjustment mechanism deferral         $ (2,000) $ 3,100  
Subsequent Event | Idaho Power Cost Adjustment              
Regulatory Matters              
Public Utilities, Requested Rate Increase (Decrease), Amount       $ (51,600)      
Subsequent Event | Idaho fixed cost adjustment mechanism              
Regulatory Matters              
Public Utilities, Requested Rate Increase (Decrease), Amount       5,100      
Subsequent Event | Oregon jurisdiction              
Regulatory Matters              
Public Utilities, Requested Rate Increase (Decrease), Amount       (1,500)      
Subsequent Event | Oregon Power Cost Adjustment Wildfire              
Regulatory Matters              
Public Utilities, Requested Rate Increase (Decrease), Amount       $ (1,900)      
Subsequent Event | Wildfire mitigation plan costs | Oregon jurisdiction | 2025              
Regulatory Matters              
Public Utilities, Requested Rate Increase (Decrease), Amount     $ 3,100        
IDAHO | 2023 Settlement Stipulation              
Regulatory Matters              
Minimum authorized return on equity             9.12%
IDAHO | October 2025 Settlement Stipulation              
Regulatory Matters              
Annual amortization cap $ 55,000            
IDAHO | Wildfire Mitigation Plan Deferral              
Regulatory Matters              
Regulatory Asset 89,600            
IDAHO | Wildfire Mitigation Plan Deferral | 2025 Rate Case              
Regulatory Matters              
Regulatory Asset 70,900            
Oregon jurisdiction | Wildfire Mitigation Plan Deferral              
Regulatory Matters              
Regulatory Asset 3,400            
Oregon jurisdiction | Wildfire Mitigation Plan Deferral | 2025 Rate Case              
Regulatory Matters              
Regulatory Asset $ 600