Represents the interest coverage ratio required to be maintained for debt instrument.

No definition available.

Name:	awr_DebtInstrumentCovenantInterestCoverageRatio
Namespace Prefix:	awr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the maximum amount of letters of credit that may be issued expressed as a percentage of the maximum borrowing capacity of the facility.

+ References

No definition available.

+ Details

Name:	awr_DebtInstrumentLetterOfCreditIssuedMaximumBorrowingCapacityPercentage
Namespace Prefix:	awr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the term of the debt instrument.

+ References

No definition available.

+ Details

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

- Definition

Ratio of Indebtedness to EBITDA

+ References

No definition available.

+ Details

Name:	awr_RatioofIndebtednesstoEBITDA
Namespace Prefix:	awr_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

+ Details

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

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

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

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

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

- Definition

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

+ References

No definition available.

+ Details

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

- 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

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

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

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

+ Details

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

- Definition

The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 14

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfLongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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

- Details

Name:	us-gaap_LongtermDebtTypeAxis=awr_NotesPayable3.45PercentDue2029Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Long-Term Debt (Details 3) (USD $)	12 Months Ended
Long-Term Debt (Details 3) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 23, 2014	Mar. 31, 2014	Oct. 31, 2009
Long-term debt
Loan proceeds received for reimbursement of costs of conversion	$ 14,846,000	$ 60,000	$ 3,408,000
Notes Payable 3.45 Percent Due 2029 [Member]
Long-term debt
Interest rate (as a percent)	3.45%	3.45%
GSWC
Long-term debt
Ratio of Indebtedness to EBITDA	2.3695
Loan proceeds received for reimbursement of costs of conversion	14,846,000	60,000	3,408,000
GSWC \| Maximum
Long-term debt
Ratio of Indebtedness to EBITDA	8.0000
GSWC \| Private Placement Notes [Member]
Long-term debt
Debt Instrument Covenant Interest Coverage Ratio	400.00%
GSWC \| Private Placement Notes [Member] \| Minimum [Member]
Long-term debt
Debt Instrument Covenant Interest Coverage Ratio	200.00%
GSWC \| Notes Payable 3.45 Percent Due 2029 [Member]
Long-term debt
Debt Instrument, Face Amount				15,000,000
Interest rate (as a percent)	3.45%	3.45%			3.45%
GSWC \| American Recovery and Reinvestment Act Obligation due 2033
Long-term debt
Maximum amount of loan that can be borrowed						9,000,000.0
Interest rate (as a percent)	2.50%
Maturity term	20 years
Loan proceeds received for reimbursement of costs of conversion	8,600,000
GSWC \| American Recovery and Reinvestment Act Obligation due 2033 \| Letters of credit to CDHP
Long-term debt
Letters of credit issued, percentage of maximum available under facility	80.00%
Amount of debt issued	$ 6,700,000.0