Income Taxes: (Details)	3 Months Ended
Mar. 31, 2013
Changes in Tax Law:
Bonus depreciation for qualifying property as extended under the Tax Relief Acts (as a percent)	50.00%

Represents the bonus depreciation percentage for qualifying property as extended under the Tax Relief Acts.

No definition available.

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