Annual fixed cost adjustment mechanism deferral amount, whether approved or requested.

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- Definition

Authorized Return on Equity in Rate Case, Mid-point

+ References

No definition available.

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- Definition

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

+ References

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- Definition

Percentage cap on the FCA adjustment.

+ References

No definition available.

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- Definition

Rate Case [Line Items]

+ References

No definition available.

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- Definition

Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to investment tax credit.

+ References

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- Definition

Amount of public utility's approved rate increase (decrease) by regulatory agency.

+ References

No definition available.

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- Definition

Amount of public utility's requested rate increase (decrease) with regulatory agency.

+ References

No definition available.

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- Definition

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

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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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REGULATORY MATTERS: Level 4 (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended		12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	May 31, 2020	May 31, 2019	Jun. 01, 2019	Dec. 31, 2018	Jun. 01, 2018	Apr. 30, 2018	Jun. 01, 2017	Oct. 31, 2014
Regulatory Matters
Revenue from contracts with customers		$ (307,779)	$ (331,298)	$ (643,180)	$ (620,871)
Power cost adjustment mechanism
Regulatory Matters
Amount of approved rate change							$ (30,400)
Idaho fixed cost adjustment mechanism
Regulatory Matters
Amount of approved rate change							19,400
Annual fixed cost adjustment mechanism deferral								$ 34,800		$ 15,600		$ 35,000
Percentage cap on the FCA adjustment								3.00%
October 2014 Idaho Settlement Stipulation \| IDAHO
Regulatory Matters
Minimum authorized return on equity													9.50%
May 2018 Tax Reform Settlement Stipulation \| IDAHO
Regulatory Matters
Minimum authorized return on equity											9.40%
Target authorized return on equity											10.00%
Settlement Stipulation - Investment Tax Credits and Idaho Sharing Mechanism [Member]
Regulatory Matters
Additional accumulated deferred investment tax credits (ADITC) amortization			$ 500	0
Non-recurring [Member] \| May 2018 Tax Reform Settlement Stipulation \| IDAHO
Regulatory Matters
Amount of approved rate change							$ 7,800
Subsequent event \| Power cost adjustment mechanism
Regulatory Matters
Amount of approved rate change						$ (50,100)
Subsequent event \| Idaho fixed cost adjustment mechanism
Regulatory Matters
Amount of approved rate change						19,200
Subsequent event \| Non-recurring [Member] \| May 2018 Tax Reform Settlement Stipulation \| IDAHO
Regulatory Matters
Amount of approved rate change						$ (2,700)
Settlement agreement sharing [Member]
Regulatory Matters
Regulatory liabilities									$ 5,000
Base rate adjustment request for potential Valmy closure [Member] [Member] \| IDAHO
Regulatory Matters
Amount of approved rate change				$ 1,200
Base rate adjustment request for potential Valmy closure [Member] [Member] \| Subsequent event \| OREGON
Regulatory Matters
Public Utilities, Requested Rate Increase (Decrease), Amount	$ 3,200