REGULATORY MATTERS: Level 4 (Details) - USD ($) $ in Thousands		3 Months Ended		12 Months Ended
	Oct. 15, 2024	Mar. 31, 2024	Mar. 31, 2023	May 31, 2025	Jun. 01, 2024	Jun. 01, 2023	Jun. 01, 2022	Jun. 01, 2020	May 31, 2018
Settlement Stipulation - Investment Tax Credits and Idaho Sharing Mechanism
Regulatory Matters
Additional accumulated deferred investment tax credits (ADITC) amortization		$ 12,500	$ 3,750
Investment Tax Credits, Remains Available		$ 73,500
Idaho fixed cost adjustment mechanism
Regulatory Matters
Percentage cap on the FCA adjustment								3.00%
Idaho Jurisdiction Fixed Cost Adjustment
Regulatory Matters
Annual fixed cost adjustment mechanism deferral						$ 36,800	$ 25,100
Subsequent Event | Idaho Power Cost Adjustment
Regulatory Matters
Public Utilities, Requested Rate Increase (Decrease), Amount				$ 35,700
Subsequent Event | Oregon jurisdiction
Regulatory Matters
Annual Power Cost Update					$ 6,900
Subsequent Event | Idaho Power Fixed Cost Adjustment
Regulatory Matters
Public Utilities, Requested Rate Increase (Decrease), Amount				$ 11,700
IDAHO | 2023 Settlement Stipulation
Regulatory Matters
Minimum authorized return on equity									9.12%
Authorized Return on Equity in Rate Case, Maximum									9.60%
Investment Tax Credits Maximum In One Year In Rate Case									$ 25,000
OREGON | Subsequent Event | Idaho Power Company
Regulatory Matters
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount	$ 10,700
Public Utilities, Requested Rate Increase (Decrease), Amended, Percentage	19.28%
Public Utilities, Requested Return on Equity, Percentage	10.40%
OREGON | Subsequent Event | Idaho Power Company | Cost of Capital and Capital Structure
Regulatory Matters
Total Retail Rate Base	$ 188,900
Requested Rate of Return	7.807%