Energy Purchase Contracts (Future Contractual Commitments For Power Resources And Natural Gas Resources) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013
Energy Purchase Contracts [Line Items]
2014	$ 304,344
2015	189,932
2016	159,235
2017	153,416
2018	143,770
Thereafter	1,357,976
Total	2,308,673
Power Resources [Member]
Energy Purchase Contracts [Line Items]
2014	201,693
2015	125,072
2016	112,570
2017	110,405
2018	106,200
Thereafter	874,990
Total	1,530,930
Natural Gas Resources [Member]
Energy Purchase Contracts [Line Items]
2014	102,651
2015	64,860
2016	46,665
2017	43,011
2018	37,570
Thereafter	482,986
Total	777,743
Generation Transmission And Distribution Facilities [Member]
Energy Purchase Contracts [Line Items]
2014	30,197
2015	27,236
2016	30,543
2017	29,199
2018	23,534
Thereafter	211,392
Total	$ 352,101

Name:	ava_EnergyPurchaseContractsLineItems
Namespace Prefix:	ava_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the fifth fiscal year following the latest fiscal year.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 440

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308

+ Details

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the next fiscal year following the latest fiscal year.

+ References

+ Details

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the four fiscal year following the latest fiscal year.

+ References

+ Details

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the second fiscal year following the latest fiscal year.

+ References

+ Details

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the third fiscal year following the latest fiscal year.

+ References

+ Details

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of the unrecorded obligation to transfer funds in the future for fixed or minimum amounts or quantities of goods or services at fixed or minimum prices (for example, as in take-or-pay contracts or throughput contracts).

+ References

+ Details

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing after the fifth fiscal year following the latest fiscal year.

+ References

+ Details

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant