REGULATORY MATTERS: December 2011 Idaho Settlement Agreement (Details) (USD $) In Millions, unless otherwise specified	Jan. 13, 2010 January 2010 Idaho Settlement Agreement	Dec. 31, 2012 December 2011 Idaho Settlement Agreement	Dec. 27, 2011 December 2011 Idaho Settlement Agreement
December 2011 Idaho Settlement Agreement [Line Items]
Authorized Return on Equity in Rate Case, Minimum	9.50%		9.50%
Authorized Return on Equity in Rate Case, Mid-point			10.00%
Authorized Return on Equity in Rate Case, Maximum	10.50%		10.50%
Investment Tax Credits, Maximum, in Rate Case			$ 45
Percentage to be Shared with Customers	50.00%	75.00%	75.00%
Percentage to be Shared with Entity			25.00%

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

No definition available.

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

- Definition

Authorized Return on Equity in Rate Case, Mid-point

+ References

No definition available.

+ Details

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

- Definition

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

+ References

No definition available.

+ Details

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

- Details

Name:	ida_December2011IdahoSettlementAgreementLineItems
Namespace Prefix:	ida_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- 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

Name:	ida_InvestmentTaxCreditsMaximumInRateCase
Namespace Prefix:	ida_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage of earnings to be Shared with Customers that is above the maximum 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 maximum 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