CHANGES IN ACCUMULATED OTHER COMPREHENSIVE INCOME Reclassifications out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reclassifications out of Accumulated Other Comprehensive Income before Tax [Abstract]
Reclassifications		$ 2,988	$ 1,952	$ 2,886
Accumulated Defined Benefit Pension Items
Reclassifications out of Accumulated Other Comprehensive Income before Tax [Abstract]
Amortization of prior service cost	[1]	290	96	98
Amortization of net loss	[1]	3,734	2,533	3,788
Total reclassifications, before tax - pension and postretirement benefits	[1]	4,024	2,629	3,886
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	[2]	(1,036)	(677)	(1,000)
Total reclassification, net of tax - pension and postretirement benefits		2,988	1,952	2,886
Reclassifications		$ 2,988	$ 1,952	$ 2,886

[1] Amortization of these items is included in "Other (income) expense, net" in the consolidated income statements of both IDACORP and Idaho Power.

[2] The tax benefit is included in "Income tax expense" in the consolidated income statements of both IDACORP and Idaho Power