Represents the number of stock incentive plans of the entity.

No definition available.

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Data Type:	xbrli:integerItemType
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- Definition

Period in which 33% vesting rights is earned by awardeed of the grant, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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

- Definition

Represents the common stock entitled to be received under each share-based payment award.

+ References

No definition available.

+ Details

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Namespace Prefix:	awr_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The period of time, from the grant date until the time at which the share-based [option] award expires.

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Share Based Compensation Arrangements by Share Based Payment Award Options, Minimum Age for Awards to Vest Immediately

+ References

No definition available.

+ Details

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Namespace Prefix:	awr_
Data Type:	xbrli:durationItemType
Balance Type:	na
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- Definition

Description of award terms as to how many shares or portion of an award are no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in the third year from the date of grant, thereby giving the employee the legal right to convert the award to shares, expressed as a percentage.

+ References

No definition available.

+ Details

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

- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 14.F)

-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (h)(1)(i)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 14

-Section F

+ Details

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

- Definition

Represents the compensation cost capitalized during the period arising from equity-based compensation arrangements (for example, shares of stock, units, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (h)(1)(ii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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

- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

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

- Definition

Gross number of share options (or share units) granted during the period.

+ References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Details

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

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_EmployeeStockOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_PerformanceSharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockUnitsRSUMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=awr_DirectorsPlan2003Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=awr_EmployeePlans2000And2008Member
Namespace Prefix:
Data Type:	na
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Stock-Based Compensation Plans (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended			3 Months Ended
	Dec. 31, 2014 stock_plan	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Stock compensation plans
Number of stock incentive plans	4awr_NumberOfStockIncentivePlans
Stock-based compensation recognized in the income statement, before taxes	$ 2,222	$ 2,009	$ 1,931
Immediate vesting for employees of certain age and above	55 years
GSWC
Stock compensation plans
Stock-based compensation recognized in the income statement, before taxes	1,748	1,647	1,667
Capitalized equity-based compensation cost	255	334	259
Nonqualified stock options
Stock compensation plans
Granted (in shares)	0			0	0
Nonqualified stock options \| Employees and directors
Stock compensation plans
Stock-based compensation recognized in the income statement, before taxes	0	9	150
Nonqualified stock options \| Employees and directors \| GSWC
Stock compensation plans
Stock-based compensation recognized in the income statement, before taxes	0	8	147
Restricted Stock Units \| Employees
Stock compensation plans
Stock-based compensation recognized in the income statement, before taxes	1,354	1,507	1,729
Restricted Stock Units \| Employees \| GSWC
Stock compensation plans
Stock-based compensation recognized in the income statement, before taxes	1,113	1,266	1,468
Performance awards
Stock compensation plans
Vesting period	3 years
Performance awards \| Officer
Stock compensation plans
Stock-based compensation recognized in the income statement, before taxes	868	493	52
Performance awards \| Officer \| GSWC
Stock compensation plans
Stock-based compensation recognized in the income statement, before taxes	$ 635	$ 373	$ 52
2000 and 2008 Employee Plans \| Nonqualified stock options
Stock compensation plans
Expiration term	10 years
Vesting period	3 years
Percentage of rights vesting in the first two years from the date of grant	33.00%
Percentage of rights vesting in the third year from the date of grant	34.00%
2000 and 2008 Employee Plans \| Restricted Stock Units
Stock compensation plans
Vesting period	3 years
Common stock entitled to be received under each award	1
Percentage of rights vesting in the first two years from the date of grant	33.00%
Percentage of rights vesting in the third year from the date of grant	34.00%
2000 and 2008 Employee Plans \| Performance awards
Stock compensation plans
Vesting period	3 years
Percentage of rights vesting in the first two years from the date of grant	33.00%
Percentage of rights vesting in the third year from the date of grant	34.00%
2003 Directors Plan \| Nonqualified stock options
Stock compensation plans
Expiration term	10 years
Vesting period	3 years