Derivative Activity Volume

No definition available.

Name:	awr_DerivativeActivityVolume
Namespace Prefix:	awr_
Data Type:	num:energyItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of Broker Quotes Received to Determine Fair Value of Derivative Instrument

+ References

No definition available.

+ Details

Name:	awr_NumberofBrokerQuotesReceivedtoDetermineFairValueofDerivativeInstrument
Namespace Prefix:	awr_
Data Type:	xbrli:integerItemType
Balance Type:	na
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.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeInstrumentsGainLossLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- 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

No definition available.

+ Details

Name:	us-gaap_DerivativeTermOfContract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- 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.

+ Details

Name:	us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of unrealized gain (loss) recognized in the income statement for a 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.

+ References

+ Details

Name:	us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19279-110258

+ Details

Name:	us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	dei_LegalEntityAxis=awr_GoldenStateWaterCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CommodityContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Derivative Instruments (Details) - GOLDEN STATE WATER COMPANY MWh in Thousands, $ in Thousands		1 Months Ended	3 Months Ended		6 Months Ended
	Jun. 30, 2017 USD ($) MWh quote	Dec. 31, 2014	Jun. 30, 2017 USD ($) quote	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) quote	Jun. 30, 2016 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Description of derivative activity volume \| MWh	276
Commodity Contract
Derivative Instruments, Gain (Loss) [Line Items]
Number of broker quotes received to determine fair value of derivative instrument \| quote	1		1		1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value at beginning of the period			$ (5,460)	$ (7,245)	$ (4,901)	$ (7,053)
Unrealized gain on purchased power contracts			967	2,312	408	2,120
Fair value at end of the period	$ (4,493)		$ (4,493)	$ (4,933)	$ (4,493)	$ (4,933)
Minimum \| Commodity Contract
Derivative Instruments, Gain (Loss) [Line Items]
Term of derivative contract		3 years
Maximum \| Commodity Contract
Derivative Instruments, Gain (Loss) [Line Items]
Term of derivative contract		5 years