REGULATORY MATTERS: Level 4 (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended		12 Months Ended
	Oct. 15, 2024	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2025	May 31, 2025	Jan. 01, 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		$ 7.5	$ 3.8	$ 20.0	$ 7.5
Investment Tax Credits, Remains Available		$ 65.1		$ 65.1
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										$ 36.8	$ 25.1
Oregon jurisdiction
Regulatory Matters
Annual Power Cost Update									$ 6.9
Subsequent Event | Idaho Power Cost Adjustment
Regulatory Matters
Public Utilities, Approved Rate Increase (Decrease), Amount							$ (35.7)
Subsequent Event | Idaho Power Fixed Cost Adjustment
Regulatory Matters
Public Utilities, Approved Rate Increase (Decrease), Amount							$ 11.7
IDAHO | 2023 Settlement Stipulation
Regulatory Matters
Minimum authorized return on equity													9.12%
IDAHO | Subsequent Event | Idaho Power Company | limited-issue rate case revenue increase requested
Regulatory Matters
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount						$ 99.3
Public Utilities, Requested Rate Increase (Decrease), Amended, Percentage						7.31%
IDAHO | Subsequent Event | Idaho Power Company | Incremental plant additions and O&M labor costs
Regulatory Matters
Incremental plant additions								$ 730.0
OREGON | Subsequent Event | Idaho Power Company
Regulatory Matters
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount	$ 10.7
Public Utilities, Requested Return on Equity, Percentage	10.40%
Public Utilities, Requested Rate Increase (Decrease), Amended, Percentage	19.28%
OREGON | Subsequent Event | Idaho Power Company | Cost of Capital and Capital Structure
Regulatory Matters
Requested Rate of Return	7.807%
Total Retail Rate Base	$ 188.9
OREGON | Subsequent Event | 2023 Rate Case
Regulatory Matters
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount	$ 6.7
Public Utilities, Requested Return on Equity, Percentage	9.50%
Public Utilities, Requested Rate Increase (Decrease), Amended, Percentage	12.14%
OREGON | Subsequent Event | 2023 Rate Case | Cost of Capital and Capital Structure
Regulatory Matters
Public Utilities, Requested Rate Increase (Decrease), Percentage	7.302%