COMMITMENTS: Level 4 (Details)	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)
Idaho Power Company
Guarantor Obligations
IERCo ownership interest in BCC	33.00%	33.00%
IERCo guarantee of BCC reclamation obligation	$ 58,300,000	$ 58,300,000
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract]
Life of Contract		20 years
Increase of Long-term Purchase Obligations, PURPA	24,000,000	$ 24,000,000
Increase of Long-term Purchase Obligations, Solar	136,000,000	136,000,000
Bridger Coal Company
Guarantor Obligations
IERCo guarantee of BCC reclamation obligation	175,000,000.0	175,000,000.0
Guarantor Obligations Total Reclamation Trust Fund	$ 125,900,000	125,900,000
Distribution from Reclamation Trust Fund		$ 0