COMMITMENTS: Commitments Level 4 (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) MWh	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2023 MWh
Bridger Coal Company
Long-term Purchase Commitment
IERCo guarantee of BCC reclamation obligation	$ 175,000
Distributions from Reclamation Trust Fund	4,800
Guarantor Obligations Total Reclamation Trust Fund	$ 183,300
Idaho Power Company
Long-term Purchase Commitment
Range of contract length, mimimum	1 year
Range of contract length, maximum	35 years
Utilities Operating Expense, Purchased Power under Long-term Contracts	$ 194,000	$ 187,000	$ 190,000
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage	33.00%
IERCo guarantee of BCC reclamation obligation	$ 58,300
Idaho Power Company | Joint-operating agreement payment [Member]
Long-term Purchase Commitment
Purchase Obligation Estimated Due Current	2,649
Purchase Obligation Estimated Future Payments Due In Two Years	2,649
Purchase Obligation Estimated Future Payments Due In Three Years	2,649
Purchase Obligation Estimated Future Payments Due In Four Years	2,649
Purchase Obligation Estimated Future Payments Due In Five Years	2,649
Purchase Obligation Estimated Future Payments Due In Six Years And Thereafter	13,243
Idaho Power Company | Easements and Other payments [Member]
Long-term Purchase Commitment
Purchase Obligation Estimated Due Current	2,037
Purchase Obligation Estimated Future Payments Due In Two Years	1,074
Purchase Obligation Estimated Future Payments Due In Three Years	1,090
Purchase Obligation Estimated Future Payments Due In Four Years	1,081
Purchase Obligation Estimated Future Payments Due In Five Years	1,075
Purchase Obligation Estimated Future Payments Due In Six Years And Thereafter	17,272
Idaho Power Company | Other operations and maintenance
Long-term Purchase Commitment
Purchase Obligation Estimated Due Current	50,761
Purchase Obligation Estimated Future Payments Due In Two Years	18,472
Purchase Obligation Estimated Future Payments Due In Three Years	9,427
Purchase Obligation Estimated Future Payments Due In Four Years	7,573
Purchase Obligation Estimated Future Payments Due In Five Years	5,737
Purchase Obligation Estimated Future Payments Due In Six Years And Thereafter	50,705
Idaho Power Company | FERC and other industry-related fees
Long-term Purchase Commitment
Purchase Obligation Estimated Due Current	14,394
Purchase Obligation Estimated Future Payments Due In Two Years	12,886
Purchase Obligation Estimated Future Payments Due In Three Years	13,090
Purchase Obligation Estimated Future Payments Due In Four Years	13,303
Purchase Obligation Estimated Future Payments Due In Five Years	13,524
Purchase Obligation Estimated Future Payments Due In Six Years And Thereafter	$ 68,766
Idaho Power Company | CSPP on-line [Member]
Long-term Purchase Commitment
Nameplate Capacity (in MW) | MWh	1,134
Idaho Power Company | Cogeneration and power production
Long-term Purchase Commitment
Purchase Obligation Estimated Due Current	$ 254,550
Purchase Obligation Estimated Future Payments Due In Two Years	258,369
Purchase Obligation Estimated Future Payments Due In Three Years	269,196
Purchase Obligation Estimated Future Payments Due In Four Years	272,955
Purchase Obligation Estimated Future Payments Due In Five Years	279,454
Purchase Obligation Estimated Future Payments Due In Six Years And Thereafter	2,541,281
Idaho Power Company | Fuel purchase commitments
Long-term Purchase Commitment
Purchase Obligation Estimated Due Current	41,818
Purchase Obligation Estimated Future Payments Due In Two Years	14,529
Purchase Obligation Estimated Future Payments Due In Three Years	8,379
Purchase Obligation Estimated Future Payments Due In Four Years	8,370
Purchase Obligation Estimated Future Payments Due In Five Years	8,362
Purchase Obligation Estimated Future Payments Due In Six Years And Thereafter	66,709
IDACORP [Member] | FERC and other industry-related fees
Long-term Purchase Commitment
Long-term Purchase Commitment, Amount	3,000
Forecast [Member] | Capacity [Member] | Idaho Power Company | CSPP not on-line [Member]
Long-term Purchase Commitment
Nameplate Capacity (in MW) | MWh				6
Contracts with no expiration [Member] | Idaho Power Company | Joint-operating agreement payment [Member]
Long-term Purchase Commitment
Purchase Obligation	26,000
Contracts with no expiration [Member] | Idaho Power Company | Other operations and maintenance
Long-term Purchase Commitment
Purchase Obligation	21,000
Contracts with no expiration [Member] | Idaho Power Company | FERC and other industry-related fees
Long-term Purchase Commitment
Purchase Obligation	135,000
Contracts with no expiration [Member] | IDACORP [Member] | FERC and other industry-related fees
Long-term Purchase Commitment
Long-term Purchase Commitment, Amount	$ 2,000