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Long-Term Debt- Additional Information (Details) - First Mortgage [Member] $ in Millions	Dec. 31, 2021 USD ($)
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	8.00%
Avista Utilities [Member]
Debt Instrument [Line Items]
Amount of First Mortgage Bonds that Could be Issued, Percent	66.66%
Amount of First Mortgage Bonds that Could be Issued	$ 1,800.0
Alaska Electric Light & Power [Member]
Debt Instrument [Line Items]
Amount of First Mortgage Bonds that Could be Issued, Percent	66.66%
Amount of First Mortgage Bonds that Could be Issued	$ 38.2

X

- Definition

Amount Of First Mortgage Bonds That Could Be Issued

+ References

No definition available.

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- Definition

Amount of First Mortgage Bonds that Could be Issued, Percent

+ References

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X

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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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

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- Details

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