CHANGES IN ACCUMULATED OTHER COMPREHENSIVE INCOME: Level 4 (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Reclassification out of Accumulated Other Comprehensive Income
Amortization of prior service cost	[1]	$ 24	$ 25	$ 48	$ 49
Amortization of net loss	[1]	633	947	1,266	1,894
Total reclassification, before tax - pension and postretirement benefits		657	972	1,314	1,943
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	[2]	(169)	(250)	(338)	(500)
Reclassifications		488	722	976	1,443
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
AOCI - Beginning Balance		(22,356)	(30,243)	(22,844)	(30,964)
Reclassifications		488	722	976	1,443
AOCI - Ending Balance		(21,868)	(29,521)	(21,868)	(29,521)
Accumulated Defined Benefit Pension Items
Reclassification out of Accumulated Other Comprehensive Income
Reclassifications		488	722	976	1,443
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
AOCI - Beginning Balance		(22,356)	(30,243)	(22,844)	(30,964)
Reclassifications		488	722	976	1,443
AOCI - Ending Balance		$ (21,868)	$ (29,521)	$ (21,868)	$ (29,521)

[1] Amortization of these items is included in IDACORP's condensed consolidated income statements in other operating expenses and in Idaho Power's condensed consolidated statements of income in other expense, net.

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