Represents amount billed to customers as surcharges.

No definition available.

Name:	awr_RegulatoryAssetAmountBilledToCustomersAsSurcharges
Namespace Prefix:	awr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the regulatory asset not accruing carrying costs as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	awr_RegulatoryAssetNotAccruingCarryingCosts
Namespace Prefix:	awr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the recovery periods of the surcharge billed to the customers.

+ References

No definition available.

+ Details

Name:	awr_RegulatoryAssetRecoveryPeriods
Namespace Prefix:	awr_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

-- None. No documentation exists for this element. --

+ References

No definition available.

+ Details

Name:	awr_RegulatoryAssetsAndLiabilitiesLineItems
Namespace Prefix:	awr_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The net amount of all regulatory assets less all regulatory liabilities as of the end of the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 340
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382

+ Details

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

- Definition

Amount of liabilities classified as other, due within one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.20)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=82887183&loc=d3e6904-107765

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=82887183&loc=d3e6911-107765

+ Details

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

- Details

Name:	us-gaap_RegulatoryAssetAxis=awr_WaterRevenueAdjustmentMechanismNetOfModifiedCostBalancingAccountMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RegulatoryAssetAxis=awr_PensionCostsAndOtherPostretirementBenefitCostsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RegulatoryAssetAxis=us-gaap_GainLossOnDerivativeInstrumentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_RegulatoryAssetAxis=awr_CostsDeferredForFutureRecoveryOnAerojetCaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RegulatoryAssetAxis=awr_FlowThroughTaxesNetMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RegulatoryAssetAxis=awr_LowIncomeRateAssistanceBalancingAccountsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RegulatoryAssetAxis=awr_GeneralRateCaseMemorandumAccountsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RegulatoryAssetAxis=awr_OtherRegulatoryAssetsNetMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RegulatoryLiabilityAxis=us-gaap_RevenueSubjectToRefundMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=awr_WaterServiceUtilityOperationsMember
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:

- Details

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

Regulatory Matters: (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Regulatory Matters: (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Regulatory matters:
Regulatory asset not accruing carrying costs	$ 55,700		$ 55,700
Other Liabilities, Current	12,434		$ 12,434		$ 11,297
Water Revenue Adjustment Mechanism, net of Modified Cost Balancing Account
Regulatory matters:
Regulatory Asset Recovery Periods			24 months
Pension and other post-retirement obligations
Regulatory matters:
Regulatory asset not accruing carrying costs	26,100		$ 26,100
Derivative unrealized loss
Regulatory matters:
Regulatory asset not accruing carrying costs	3,837		3,837
GOLDEN STATE WATER COMPANY
Regulatory matters:
Regulatory assets	130,906		130,906		146,281
Other Liabilities, Current	12,088		12,088		10,925
GOLDEN STATE WATER COMPANY \| Water Revenue Adjustment Mechanism, net of Modified Cost Balancing Account
Regulatory matters:
Regulatory Asset Amount Billed to Customers as Surcharges	11,400	$ 6,500	24,800	$ 12,900
Regulatory assets	40,230		40,230		47,340
GOLDEN STATE WATER COMPANY \| Costs deferred for future recovery on Aerojet case
Regulatory matters:
Regulatory assets	10,983		10,983		11,820
GOLDEN STATE WATER COMPANY \| Pension and other post-retirement obligations
Regulatory matters:
Regulatory assets	24,944		24,944		28,118
GOLDEN STATE WATER COMPANY \| Derivative unrealized loss
Regulatory matters:
Regulatory assets					4,901
GOLDEN STATE WATER COMPANY \| Flow-through taxes, net
Regulatory matters:
Regulatory assets	21,231		21,231		20,134
GOLDEN STATE WATER COMPANY \| Low income rate assistance balancing accounts
Regulatory matters:
Regulatory assets	6,779		6,779		8,272
GOLDEN STATE WATER COMPANY \| General Rate Case Memorandum Accounts [Member]
Regulatory matters:
Regulatory assets	12,369		12,369		13,929
GOLDEN STATE WATER COMPANY \| Other regulatory assets
Regulatory matters:
Regulatory assets	15,322		15,322		17,633
GOLDEN STATE WATER COMPANY \| Various refunds to customers
Regulatory matters:
Regulatory assets	(4,789)		(4,789)		$ (5,866)
Water Service Utility Operations \| General Rate Case Memorandum Accounts [Member]
Regulatory matters:
Regulatory assets	$ 9,900		$ 9,900
Maximum \| GOLDEN STATE WATER COMPANY \| Water Revenue Adjustment Mechanism, net of Modified Cost Balancing Account
Regulatory matters:
Regulatory Asset Recovery Periods			24 months
Maximum \| GOLDEN STATE WATER COMPANY \| General Rate Case Memorandum Accounts [Member]
Regulatory matters:
Regulatory Asset Recovery Periods			36 months
Minimum \| GOLDEN STATE WATER COMPANY \| General Rate Case Memorandum Accounts [Member]
Regulatory matters:
Regulatory Asset Recovery Periods			12 months