Line Of Credit Facility Expiration Period

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Namespace Prefix:	ava
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Ratio Required to Comply With Customary Covenants

+ Details

Name:	ava_RatioRequiredToComplyWithCustomaryCovenants
Namespace Prefix:	ava
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount borrowed under the credit facility as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

Name:	us-gaap_LineOfCreditFacilityAmountOutstanding
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Reflects when the credit facility terminates, which may be presented in a variety of ways (year, month and year, day, month and year, quarter).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationDate
Namespace Prefix:	us-gaap
Data Type:	us-types:dateStringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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.

+ Details

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Namespace Prefix:	us-gaap
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Balance Type:	na
Period Type:	duration

Short-Term Borrowings (Details) (USD $)	9 Months Ended			9 Months Ended				9 Months Ended
Short-Term Borrowings (Details) (USD $)	Sep. 30, 2011	Dec. 31, 2010	Apr. 30, 2011 Ecova [Member] Line Of Credit [Member]	Sep. 30, 2011 Ecova [Member]	Dec. 31, 2010 Ecova [Member]	Sep. 30, 2011 First Line Of Credit Agreement [Member]	Sep. 30, 2011 Second Line Of Credit Agreement [Member]	Sep. 30, 2011 Avista Corporation [Member]
Short-term Debt [Line Items]
Total amount of committed line of credit agreement	$ 400,000,000		$ 40,000,000	$ 15,000,000		$ 320,000,000	$ 75,000,000
Expiration date of committed line of credit agreement	2015, February			2011, May
Maximum percentage ratio of consolidated total debt to consolidated total capitalization needed to comply with covenants								65.00%
Balance outstanding at end of period	96,500,000	110,000,000		0	0
Letters of credit outstanding at end of period	$ 14,883,000	$ 27,126,000
Line of credit facility expiration period				3