INCOME TAXES: Income Tax Expense Benefit Continuing Operations Income Tax Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Expense [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		35.00%
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation
Federal income tax expense at 35% statutory rate		$ 84,154	$ 73,588	$ 89,125
AFUDC		(11,140)	(9,238)	(7,882)
Capitalized interest		2,693	2,278	1,832
Investment tax credits		(2,963)	(3,002)	(3,119)
Removal costs		(4,807)	(3,656)	(3,527)
Capitalized overhead costs		(8,750)	(8,750)	(8,750)
Capitalized repair costs		(28,700)	(26,250)	(19,250)
Bond redemption costs		(6,459)
Tax method change – capitalized repairs	$ (11,100)	0	(24,516)	4,583
State income taxes, net of federal benefit		7,343	4,680	6,730
Depreciation		17,149	16,040	14,820
Affordable housing tax credits		(3,258)	(5,189)	(5,503)
Affordable housing investment amortization		1,519	2,757	1,684
Other, net		(1,021)	(1,970)	1,483
Total income tax expense		$ 45,760	$ 16,772	$ 72,226
Effective tax rate		19.00%	8.00%	28.40%
Idaho Power Company
Income Tax Expense [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		35.00%
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation
Federal income tax expense at 35% statutory rate		$ 83,724	$ 73,116	$ 88,550
AFUDC		(11,140)	(9,238)	(7,882)
Capitalized interest		2,693	2,278	1,832
Investment tax credits		(2,963)	(3,002)	(3,119)
Removal costs		(4,807)	(3,656)	(3,527)
Capitalized overhead costs		(8,750)	(8,750)	(8,750)
Capitalized repair costs		(28,700)	(26,250)	(19,250)
Bond redemption costs		(6,459)
Tax method change – capitalized repairs		0	(24,516)	4,583
State income taxes, net of federal benefit		7,503	5,334	6,970
Depreciation		17,149	16,040	14,820
Other, net		(22)	(1,840)	2,033
Total income tax expense		$ 48,228	$ 19,516	$ 76,260
Effective tax rate		20.20%	9.30%	30.10%
IDACORP
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation
Total income tax expense		$ (1,404)	$ (1,455)	$ (1,378)