SEGMENT INFORMATION (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues	$ 1,346,383	$ 1,370,752	$ 1,349,486
Electric utility revenues	1,342,940	1,366,582	1,344,893
Operating income	298,326	296,922	315,545
Other income	20,363	11,645	12,547
Interest income	13,251	9,841	6,128
Earnings of unconsolidated equity-method investments	12,370	12,449	11,374
Interest expense	86,475	85,948	83,746
Income before income taxes	257,835	244,909	261,848
Income tax expense (benefit)	24,507	17,386	48,660
Income attributable to IDACORP, Inc.	233,328	227,523	213,188
Income attributable to IDACORP, Inc.	232,854	226,801	212,419
Total assets	6,641,201	6,382,754	6,045,405
Expenditures for long-lived assets	278,705	277,853	285,488
Idaho Power Company
Segment Reporting Information [Line Items]
Electric utility revenues	1,342,940	1,366,582	1,344,893
Operating income	297,652	295,256	313,602
Other income	20,362	11,646	12,356
Interest income	10,968	8,923	6,044
Earnings of unconsolidated equity-method investments	10,285	10,712	9,267
Interest expense	86,412	85,891	83,660
Income before income taxes	252,854	240,646	257,609
Income tax expense (benefit)	28,417	18,312	51,262
Income attributable to IDACORP, Inc.	224,437	222,334	206,347
Total assets	6,494,159	6,254,400	5,995,435
Expenditures for long-lived assets	$ 278,707	$ 277,823	$ 285,471
IERCo's ownership percentage in Bridger Coal Company	33.00%	33.00%	33.00%
All Other
Segment Reporting Information [Line Items]
Revenues	$ 3,443	$ 4,170	$ 4,593
Operating income	674	1,666	1,943
Other income	1	(1)	191
Interest income	3,052	1,573	295
Earnings of unconsolidated equity-method investments	2,085	1,737	2,107
Interest expense	832	712	297
Income before income taxes	4,981	4,263	4,239
Income tax expense (benefit)	(3,910)	(926)	(2,602)
Income attributable to IDACORP, Inc.	8,417	4,467	6,072
Total assets	220,620	163,540	143,696
Expenditures for long-lived assets	(2)	30	17
Eliminations
Segment Reporting Information [Line Items]
Revenues	0	0	0
Operating income	0	0	0
Other income	0	0	0
Interest income	(769)	(655)	(211)
Earnings of unconsolidated equity-method investments	0	0	0
Interest expense	(769)	(655)	(211)
Income before income taxes	0	0	0
Income tax expense (benefit)	0	0	0
Income attributable to IDACORP, Inc.	0	0	0
Total assets	(73,578)	(35,186)	(93,726)
Expenditures for long-lived assets	$ 0	$ 0	$ 0