BENEFIT PLANS: Level 4 (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Defined Benefit Plan Disclosure
Service cost		$ 9,564	$ 6,867	$ 26,806	$ 23,658
Interest cost		15,588	15,225	45,253	44,685
Expected return on plan assets		(16,697)	(15,715)	(51,273)	(47,409)
Amortization of prior service cost		1,598	472	2,606	1,418
Amortization of net loss		(45)	(167)	(137)	(500)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)		10,008	6,682	23,255	21,852
Regulatory deferral of net periodic benefit cost	[1]	(7,269)	(4,223)	(15,320)	(14,344)
IPUC Authorized recovered pension cost	[1]	8,796	4,288	26,387	12,865
Net periodic benefit cost recognized for financial reporting	[1],[2]	11,535	6,747	34,322	20,373
Net Periodic Benefit cost recognize in Other operations and maintenance		9,400	5,100	28,200	15,500
Net Periodic Benefit cost recognized in other expense, net		2,100	1,700	6,100	4,900
Pension Plan
Defined Benefit Plan Disclosure
Service cost		9,127	6,549	25,494	22,705
Interest cost		13,549	13,149	39,136	38,458
Expected return on plan assets		(16,240)	(15,303)	(49,900)	(46,171)
Amortization of prior service cost		1,156	2	1,280	5
Amortization of net loss		0	0	0	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)		7,592	4,397	16,010	14,997
Regulatory deferral of net periodic benefit cost	[1]	(7,269)	(4,223)	(15,320)	(14,344)
IPUC Authorized recovered pension cost	[1]	8,796	4,288	26,387	12,865
Net periodic benefit cost recognized for financial reporting	[1],[2]	9,119	4,462	27,077	13,518
Pension Plan | Idaho Power Company
Defined Benefit Plan Disclosure
Defined Benefit Plan, Contributions by Employer				20,000
Senior Management Security Plan
Defined Benefit Plan Disclosure
Service cost		262	153	788	459
Interest cost		1,333	1,331	3,999	3,992
Expected return on plan assets		0	0	0	0
Amortization of prior service cost		55	54	165	164
Amortization of net loss		329	143	984	428
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)		1,979	1,681	5,936	5,043
Net periodic benefit cost recognized for financial reporting		1,979	1,681	5,936	5,043
Postretirement Benefits Plan
Defined Benefit Plan Disclosure
Service cost		175	165	524	494
Interest cost		706	745	2,118	2,235
Expected return on plan assets		(457)	(412)	(1,373)	(1,238)
Amortization of prior service cost		387	416	1,161	1,249
Amortization of net loss		(374)	(310)	(1,121)	(928)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)		437	604	1,309	1,812
Net periodic benefit cost recognized for financial reporting		$ 437	$ 604	$ 1,309	$ 1,812

[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, $9.4 million and $5.1 million, respectively, were recognized in "Other operations and maintenance" and $2.1 million and $1.7 million, respectively, were recognized in "Other income, net" on the condensed consolidated statements of income of the companies for the three months ended September 30, 2024 and 2023.