Derivatives And Risk Management (Interest Rate Swap Agreements) (Details) $ in Thousands	12 Months Ended
Dec. 31, 2015 USD ($) Caontracts	Dec. 31, 2014 USD ($) Caontracts
Derivatives, Fair Value [Line Items]
Secured Debt	$ 1,611,700	$ 1,511,700
Derivative, Fair Value, Amount Offset Against Collateral, Net	48,556	44,390
Interest Rate Swap Agreements [Member]
Derivatives, Fair Value [Line Items]
Derivative, Fair Value, Amount Offset Against Collateral, Net	$ 34,030	$ 28,880
2015 \| Interest Rate Swap Agreements [Member]
Derivatives, Fair Value [Line Items]
Number of Interest Rate Swaps Settled \| Caontracts	5
Number of contracts \| Caontracts		5
Derivative, Notional Amount		$ 75,000
Derivative, Maturity Date		Dec. 31, 2015
Settled Derivative, Notional Amount	$ 75,000
2016 \| Interest Rate Swap Agreements [Member]
Derivatives, Fair Value [Line Items]
Number of contracts \| Caontracts	6	5
Derivative, Notional Amount	$ 115,000	$ 95,000
Derivative, Maturity Date	Dec. 31, 2016	Dec. 31, 2016
2017 \| Interest Rate Swap Agreements [Member]
Derivatives, Fair Value [Line Items]
Number of contracts \| Caontracts	3	3
Derivative, Notional Amount	$ 45,000	$ 45,000
Derivative, Maturity Date	Dec. 31, 2017	Dec. 31, 2017
2018 \| Interest Rate Swap Agreements [Member]
Derivatives, Fair Value [Line Items]
Number of contracts \| Caontracts	11	9
Derivative, Notional Amount	$ 245,000	$ 205,000
Derivative, Maturity Date	Dec. 31, 2018	Dec. 31, 2018
2019 \| Interest Rate Swap Agreements [Member]
Derivatives, Fair Value [Line Items]
Number of contracts \| Caontracts	2
Derivative, Notional Amount	$ 30,000
Derivative, Maturity Date	Dec. 31, 2019
2022 \| Interest Rate Swap Agreements [Member]
Derivatives, Fair Value [Line Items]
Number of contracts \| Caontracts	1
Derivative, Notional Amount	$ 20,000
Derivative, Maturity Date	Dec. 31, 2022
Avista Utilities [Member]
Derivatives, Fair Value [Line Items]
Secured Debt	$ 1,536,700	$ 1,436,700
Avista Utilities [Member] \| 2045 \| First Mortgage [Member]
Derivatives, Fair Value [Line Items]
Secured Debt	100,000
Avista Utilities [Member] \| 2016 \| First Mortgage [Member]
Derivatives, Fair Value [Line Items]
Secured Debt	$ 90,000	$ 90,000

Number of Interest Rate Swaps Settled

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- Definition

Aggregate notional amount of the settled derivative specified by the contract. Expressed as an absolute value.

+ References

No definition available.

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- Definition

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

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- Definition

The net amount as of the balance sheet date of the fair value of derivative assets and derivative liabilities that in accordance with the entity's accounting policy were offset against collateral under a master netting arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=d3e41678-113959

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- Definition

Date the derivative contract matures, in CCYY-MM-DD format.

+ References

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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

No definition available.

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- Definition

Number of interest rate derivative instruments held by the entity at the reporting date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5579245-113959

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Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 20, 22
-Article 5

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