INCOME TAXES: Income Tax Expense Benefit Continuing Operations Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation
Federal income tax expense at statutory rate	$ 54,046	$ 51,279	$ 91,378
AFUDC	(7,941)	(7,246)	(10,318)
Capitalized interest	976	928	1,513
Investment tax credits	(6,252)	(2,929)	(3,081)
Removal costs	(3,139)	(3,471)	(6,280)
Capitalized overhead costs	(7,140)	(6,720)	(11,200)
Capitalized repair costs	(18,480)	(17,850)	(28,700)
Bond redemption costs	0	(1,029)	0
Remeasurement of deferred taxes	0	(5,411)	1,690
State income taxes, net of federal benefit	8,627	8,512	8,153
Depreciation	14,641	13,110	18,953
Excess deferred income tax reversal	(6,181)	(7,289)	0
Income tax return adjustments	745	(5,076)	(3,710)
Affordable housing tax credits	(2,874)	(2,560)	(2,559)
Affordable housing investment distributions	(3,232)	(267)	(1,124)
Affordable housing investment amortization	1,825	1,519	1,271
Other, net	(1,114)	1,886	(7,326)
Total income tax expense	$ 24,507	$ 17,386	$ 48,660
Effective tax rate	9.50%	7.10%	18.60%
Idaho Power Company
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation
Federal income tax expense at statutory rate	$ 53,099	$ 50,536	$ 90,163
AFUDC	(7,941)	(7,246)	(10,318)
Capitalized interest	976	928	1,513
Investment tax credits	(6,252)	(2,929)	(3,081)
Removal costs	(3,139)	(3,471)	(6,280)
Capitalized overhead costs	(7,140)	(6,720)	(11,200)
Capitalized repair costs	(18,480)	(17,850)	(28,700)
Bond redemption costs	0	(1,029)	0
Remeasurement of deferred taxes	0	(5,664)	1,970
State income taxes, net of federal benefit	8,401	8,532	8,108
Depreciation	14,641	13,110	18,953
Excess deferred income tax reversal	(6,181)	(7,289)	0
Income tax return adjustments	993	(4,968)	(3,601)
Affordable housing tax credits	0	0	0
Affordable housing investment distributions	0	0	0
Affordable housing investment amortization	0	0	0
Other, net	(560)	2,372	(6,265)
Total income tax expense	$ 28,417	$ 18,312	$ 51,262
Effective tax rate	11.20%	7.60%	19.90%