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Subsequent Events: (Details) | 6 Months Ended
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Jun. 30, 2017
Contracts | ASUS |
Subsequent Event [Line Items] |
Period of fixed price contracts to operate and maintain the water and/or wastewater systems at various military bases | 50 years

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- Definition Represents the period of fixed price contracts to operate and maintain the water and/or wastewater systems at various military bases. + References No definition available. + Details
Name: | awr_PeriodOfFixedPriceContractsToOperateAndMaintainWaterSystemsAtVariousMilitaryBases
Namespace Prefix: | awr_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

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- Definition Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event. + References No definition available. + Details
Name: | us-gaap_SubsequentEventLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=awr_ContractedServicesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | dei_LegalEntityAxis=awr_AmericanStatesUtilityServicesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |