COMMITMENTS: Level 4 (Details) $ in Millions	6 Months Ended
Jun. 30, 2018 USD ($)
Idaho Power Company
Guarantor Obligations
IERCo ownership interest in BCC	33.00%
IERCo guarantee of BCC reclamation obligation	$ 58.4
Long-term Purchase Commitment
Increase of Long-term Purchase Obligations, Amount	$ 51.3
Life of Contract	20 years
Bridger Coal Company
Guarantor Obligations
IERCo guarantee of BCC reclamation obligation	$ 175.2
Guarantor Obligations Total Reclamation Trust Fund	108.3
Distribution from Reclamation Trust Fund	$ 3.0

Distribution from Reclamation Trust Fund related to the guarantee obligation that exists at the balance sheet date.

No definition available.

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- Definition

Total reclamation trust fund balance related to the guarantee obligation that exists at the balance sheet date.

+ References

No definition available.

+ Details

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- Definition

The estimated amount the entity agreed to spend under a long-term purchase obligation.

+ References

No definition available.

+ Details

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- Definition

Life of Contract

+ References

No definition available.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=115931803&loc=d3e12069-110248

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- References

No definition available.

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- Definition

Percentage of the Variable Interest Entity's (VIE) voting interest owned by (or beneficial interest in) the reporting entity (directly or indirectly).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 5A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=108788376&loc=SL6759159-111685

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