REGULATORY MATTERS: Regulatory Assets and Liabilities Table (Details) - USD ($) $ in Thousands		Dec. 31, 2022	Dec. 31, 2021
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets		$ 1,501,961	$ 1,533,654
Regulatory Liabilities		860,601	792,934
Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[1]	577,887
Regulatory Liabilities	[1]	324,342
Not Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets		924,074
Regulatory Liabilities		536,259
Income taxes
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[2]	94,946	96,880
Income taxes | Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[1],[2]	0
Income taxes | Not Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[2]	94,946
Depreciation-related excess deferred income taxes
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[3]	158,634	170,039
Depreciation-related excess deferred income taxes | Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[1],[3]	158,634
Depreciation-related excess deferred income taxes | Not Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[3]	0
Removal costs
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[4]	180,087	184,670
Removal costs | Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[1],[4]	0
Removal costs | Not Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[4]	180,087
Investment tax credits
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities		115,285	109,460
Investment tax credits | Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[1]	0
Investment tax credits | Not Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities		115,285
Deferred revenue-AFUDC
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[5]	207,528	187,717
Deferred revenue-AFUDC | Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[1],[5]	159,001
Deferred revenue-AFUDC | Not Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[5]	48,527
Settlement agreement sharing mechanism
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[6]	0	569
Settlement agreement sharing mechanism | Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[1],[6]	0
Settlement agreement sharing mechanism | Not Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[6]	0
Other regulatory assets (liabilities)
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities		11,630	10,496
Other regulatory assets (liabilities) | Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[1]	6,553
Other regulatory assets (liabilities) | Not Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities		5,077
Tax reform accrual for future amortization [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[7]	32,793	24,522
Tax reform accrual for future amortization [Member] | Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[1],[7]	0
Tax reform accrual for future amortization [Member] | Not Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[7]	32,793
Derivative
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities		59,544	8,581
Derivative | Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[1]	0
Derivative | Not Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities		59,544
Energy efficiency regulatory liability
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[8]	154	0
Energy efficiency regulatory liability | Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[1],[8]	154
Energy efficiency regulatory liability | Not Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	[8]	0
Income taxes
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[9]	739,689	721,276
Income taxes | Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[1],[9]	0
Income taxes | Not Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[9]	739,689
Unfunded postretirement benefits
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[10]	70,254	315,011
Unfunded postretirement benefits | Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[1],[10]	0
Unfunded postretirement benefits | Not Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[10]	70,254
Pension expense deferrals
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[11]	249,503	234,437
Pension expense deferrals | Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[1],[11]	220,648
Pension expense deferrals | Not Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[11]	28,855
Energy efficiency regulatory asset
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[8]	3,767	7,622
Energy efficiency regulatory asset | Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[1],[8]	3,767
Energy efficiency regulatory asset | Not Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[8]	0
Power supply costs
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[6]	129,309	33,529
Power supply costs | Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[1],[6]	145,321
Power supply costs | Not Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[6]	16,012
Fixed cost adjustment
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[6]	41,901	54,944
Fixed cost adjustment | Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[1],[6]	24,859
Fixed cost adjustment | Not Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[6]	17,042
Valmy Plant settlements
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[6]	90,747	97,852
Valmy Plant settlements | Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[1],[6]	90,747
Valmy Plant settlements | Not Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[6]	0
Asset retirement obligation
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[4]	28,780	22,585
Asset retirement obligation | Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[1],[4]	0
Asset retirement obligation | Not Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[4]	28,780
Wildfire Mitigation Plan Deferral
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[6]	27,078	6,075
Wildfire Mitigation Plan Deferral | Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[1],[6]	0
Wildfire Mitigation Plan Deferral | Not Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[6]	27,078
Long-term service agreement
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets		22,114	23,273
Long-term service agreement | Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[1]	13,363
Long-term service agreement | Not Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets		8,751
Other regulatory assets (liabilities)
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets		18,288	17,050
Other regulatory assets (liabilities) | Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[1]	2,790
Other regulatory assets (liabilities) | Not Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets		15,498
Jim Bridger Plant
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[6]	80,531	$ 0
Jim Bridger Plant | Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[1],[6]	76,392
Jim Bridger Plant | Not Earning a Return
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	[6]	$ 4,139

[1] Earning a return includes either interest or a return on the investment as a component of rate base at the allowed rate of return.

[2] Represents the tax gross-up related to the depreciation-related excess deferred income taxes and investment tax credits included in this table and has a corresponding deferred tax asset disclosed in Note 2 - "Income Taxes."

[3] In 2017, income tax reform reduced deferred income tax assets and liabilities. For depreciation-related temporary differences under the normalized tax accounting method, the resulting excess deferred taxes will flow back to customers ratably over the remaining regulatory lives of Idaho Power's plant assets under the alternative method provided in the statute.

[4] Asset retirement obligations and removal costs are discussed in Note 13 - "Asset Retirement Obligations (ARO)."

[5] Idaho Power is collecting revenue in the Idaho jurisdiction for AFUDC on HCC relicensing costs but is deferring revenue recognition of the amounts collected until the license is issued and the asset is placed in service under the new license.

[6] This item is discussed in more detail in this Note 3 - "Regulatory Matters."

[7] Represents amount accrued under the May 2018 Idaho Tax Reform Settlement Stipulation (described below) for the future amortization of existing or future unspecified regulatory deferrals that would otherwise be a future liability recoverable from Idaho customers.

[8] The energy efficiency asset and liability represent the separate Idaho and Oregon jurisdiction balances at December 31, 2022.

[9] Represents flow-through income tax accounting differences which have a corresponding deferred tax liability disclosed in Note 2 - "Income Taxes."

[10] Represents the unfunded obligation of Idaho Power’s pension and postretirement benefit plans, which are discussed in Note 11 - "Benefit Plans."

[11] Idaho Power records a regulatory asset for the difference between net periodic pension cost and pension cost considered for rate-making purposes relating to Idaho Power's defined benefit pension plan. In its Idaho jurisdiction, Idaho Power’s inclusion of pension costs for the establishment of retail rates is based upon contributions made to the pension plan. This regulatory asset account represents the difference between cumulative cash contributions and amounts collected in rates. Deferred costs are amortized into expense as the amounts are provided for in Idaho retail revenues.