Derivative Instruments (Details) $ in Thousands	12 Months Ended
Dec. 31, 2020 USD ($) MWh	Dec. 31, 2019 USD ($)
GSWC \| Purchase power contract
Changes in the fair value of the derivative
Balance, at beginning of the period	$ 3,171	$ 311
Unrealized (loss) gain on purchased power contracts		(2,860)
Balance, at end of the period		$ 3,171
Bear Valley Electric Service, Inc.
Derivative instruments
Derivative Activity Volume \| MWh	487,000
Changes in the fair value of the derivative
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	$ (1,500)
Bear Valley Electric Service, Inc. \| Purchase power contract
Changes in the fair value of the derivative
Unrealized (loss) gain on purchased power contracts	1,634
Balance, at end of the period	$ (1,537)
Minimum \| Bear Valley Electric Service, Inc.
Derivative instruments
Derivative, Term of Contract	3 years
Minimum \| Bear Valley Electric Service, Inc. \| Purchase power contract
Derivative instruments
Derivative, Term of Contract	3 years
Maximum \| Bear Valley Electric Service, Inc.
Derivative instruments
Derivative, Term of Contract	5 years
Maximum \| Bear Valley Electric Service, Inc. \| Purchase power contract
Derivative instruments
Derivative, Term of Contract	5 years

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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.

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- Definition

Period the derivative contract is outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount of gain (loss) recognized in income from liability measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
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-Section 50
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- Definition

Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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- Definition

Fair value of financial instrument classified as derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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