Represents the average load at customer service area.

No definition available.

Name:	awr_AverageLoadAtCustomerServiceAreaNumberOfMegawatts
Namespace Prefix:	awr_
Data Type:	num:powerItemType
Balance Type:	na
Period Type:	duration

Represents the average winter load.

No definition available.

Name:	awr_AverageWinterLoadNumberOfMegawatts
Namespace Prefix:	awr_
Data Type:	num:powerItemType
Balance Type:	na
Period Type:	duration

Represents the fixed price of electric energy per megawatt-hour.

No definition available.

Name:	awr_FixedPriceOfElectricEnergyPerMegawatthour
Namespace Prefix:	awr_
Data Type:	us-types:perUnitItemType
Balance Type:	na
Period Type:	duration

Represents the megawatts of electric energy provided under purchased power contract.

No definition available.

Name:	awr_MegawattsOfElectricEnergyProvidedUnderPurchasedPowerContract
Namespace Prefix:	awr_
Data Type:	num:energyItemType
Balance Type:	na
Period Type:	duration

Represents the maximum capacity provided by a natural gas-fueled generation facility.

No definition available.

Name:	awr_NaturalGasFueledGenerationFacilityMaximumCapacity
Namespace Prefix:	awr_
Data Type:	num:powerItemType
Balance Type:	na
Period Type:	duration

Represents the amount of electric power purchased during the period under the shell contract.

No definition available.

Name:	awr_PurchaseOfElectricPowerUnderShellContract
Namespace Prefix:	awr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Represents the winter peak load when the snowmaking machines at the ski resorts are operating.

No definition available.

Name:	awr_WinterPeakLoadNumberOfMegawatts
Namespace Prefix:	awr_
Data Type:	num:powerItemType
Balance Type:	na
Period Type:	duration

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

Minimum amount of purchase arrangement in which the entity has agreed to expend funds to procure goods or services from a supplier.

No definition available.

Business Risks and Commitments (Details 3) (Bear Valley Electric, GSWC, USD $)	12 Months Ended
	Dec. 31, 2012 MWh	Dec. 31, 2011	Dec. 31, 2010	Jan. 02, 2009
Purchase commitments
Average load at customer service area (in MWs)	14
Average winter load (in MWs)	20
Winter peak load (in MWs)	44
Maximum capacity fo natural gas-fuled generation facility (in megawatts)	8.4
Shell
Purchase commitments
Megawatts of electric energy provided under contract	13
Fixed price of electric energy per MWh	67.15	66.40
Total commitment under agreement	$ 7,100,000			$ 41,300,000
Purchase of power under the shell contract	$ 7,800,000	$ 9,000,000	$ 9,000,000
EDF
Purchase commitments
Megawatts of electric energy provided under contract	12