Represents the term associated with a fixed-term security.

No definition available.

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

- Definition

Represents amount billed to customers as surcharges.

+ References

No definition available.

+ Details

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

- Definition

Regulatory Asset, Customer Surcharges Expected to be Collected

+ References

No definition available.

+ Details

Name:	awr_RegulatoryAssetCustomerSurchargesExpectedtobeCollected
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

- Details

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

- Definition

The increase (decrease) during the reporting period in the value of other assets that are created when regulatory agencies permits public utilities to defer costs to the balance sheet.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

+ Details

Name:	us-gaap_IncreaseDecreaseInOtherRegulatoryAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

- Details

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

- Details

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

Regulatory Matters: Alternative-Revenue Programs (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
WRAM, net of MCBA
Regulatory matters:
Increase (decrease) in other regulatory assets	$ 8,000,000	$ 3,600,000
GOLDEN STATE WATER COMPANY
Regulatory matters:
Under (over) collection	131,921,000		125,704,000
GOLDEN STATE WATER COMPANY \| WRAM, net of MCBA
Regulatory matters:
Commercial paper, term	90 days
Amount billed to customers as surcharges	600,000	1,800,000
Under (over) collection	17,948,000		9,369,000
GOLDEN STATE WATER COMPANY \| WRAM, net of MCBA \| Minimum
Regulatory matters:
Regulatory asset recovery periods	18 months
GOLDEN STATE WATER COMPANY \| WRAM, net of MCBA \| Maximum
Regulatory matters:
Regulatory asset recovery periods	24 months
GOLDEN STATE WATER COMPANY \| WRAM
Regulatory matters:
Under (over) collection	13,700,000
GOLDEN STATE WATER COMPANY \| Modified Cost Balancing Account
Regulatory matters:
Under (over) collection	4,200,000
GOLDEN STATE WATER COMPANY \| Base revenue requirement adjustment mechanism
Regulatory matters:
Under (over) collection	6,452,000		7,761,000
Customer surcharges expected to be collected	$ 3,100,000