Additional pension amortization as a result of Idaho settlement stipulation that was recorded during the year.

No definition available.

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Period Type:	duration

- Definition

The maximum authorized return on equity, whether requested or approved, in the rate case.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Authorized Return on Equity in Rate Case, Mid-point

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
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- Definition

The minimum authorized return on equity, whether requested or approved, in the rate case.

+ References

No definition available.

+ Details

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Namespace Prefix:	ida_
Data Type:	num:percentItemType
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- Definition

[Line Items] for December 2011 Idaho Settlement Agreement [Table]

+ References

No definition available.

+ Details

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- Definition

The maximum amount, whether proposed or approved, of additional investment tax credits that are allowed in the rate case that are computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to investment tax credits generated or utilized under enacted tax laws during the period.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage of earnings to be Shared with Customers that is above the applicable authorized rate of return in the rate case.

+ References

No definition available.

+ Details

Name:	ida_PercentageToBeSharedWithCustomers
Namespace Prefix:	ida_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of earnings to be Shared with the Entity that is above the applicable authorized rate of return in the rate case.

+ References

No definition available.

+ Details

Name:	ida_PercentageToBeSharedWithEntity
Namespace Prefix:	ida_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount for the individual regulatory liability as itemized in a table of regulatory liabilities as of the end of the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 405
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6500807&loc=d3e48068-110394

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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Namespace Prefix:
Data Type:	na
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- Details

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Data Type:	na
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- Details

Name:	us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
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REGULATORY MATTERS: December 2011 Idaho Settlement Agreement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2015	Dec. 27, 2011
December 2011 Idaho Settlement Agreement [Line Items]
Regulatory Liabilities	$ 401,607			$ 418,498
December 2011 Idaho Settlement Agreement
December 2011 Idaho Settlement Agreement [Line Items]
Authorized Return on Equity in Rate Case, Minimum					9.50%
Authorized Return on Equity in Rate Case, Mid-point					10.00%
Authorized Return on Equity in Rate Case, Maximum					10.50%
Investment Tax Credits, Maximum, in Rate Case					$ 45,000
Percentage to be Shared with Customers					75.00%
Percentage to be Shared with Entity					25.00%
Settlement agreement sharing [Member] \| December 2011 Idaho Settlement Agreement
December 2011 Idaho Settlement Agreement [Line Items]
Regulatory Liabilities	7,999	$ 7,600	$ 7,200	$ 3,159
Pension Plan
December 2011 Idaho Settlement Agreement [Line Items]
Additional Pension Amortization As Result Of Idaho Settlement Stipulation	$ 16,700	$ 16,500	$ 14,600