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Regulatory Matters - Four Corners and Cholla (Details) (APS, USD $) In Millions, unless otherwise specified | 0 Months Ended | 3 Months Ended
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Dec. 23, 2014 | Dec. 30, 2013 MW | Mar. 31, 2015
SCE | Four Corners Units 4 and 5 |  |  |
Business Acquisition [Line Items] |  |  |
Ownership interest acquired |  | 48.00%us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired / us-gaap_BusinessAcquisitionAxis = pnw_SouthernCaliforniaEdisonCompanyMember / us-gaap_JointlyOwnedUtilityPlantAxis = pnw_FourCornersUnits4And5Member / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember |
Settlement agreement, ACC approved rate adjustment, annualized customer impact | $ 57.1 pnw_SettlementagreementACCapprovedrateadjustmentannualizedcustomerimpact / us-gaap_BusinessAcquisitionAxis = pnw_SouthernCaliforniaEdisonCompanyMember / us-gaap_JointlyOwnedUtilityPlantAxis = pnw_FourCornersUnits4And5Member / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember |  |
Net receipt due to negotiation of alternate arrangement |  | 40 pnw_TransmissionTerminationAgreementNetReceiptDueToNegotiationOfAlternateArrangement / us-gaap_BusinessAcquisitionAxis = pnw_SouthernCaliforniaEdisonCompanyMember / us-gaap_JointlyOwnedUtilityPlantAxis = pnw_FourCornersUnits4And5Member / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember |
Capacity rights over the Arizona Transmission System assign to third-parties |  | 1,555 pnw_TransmissionTerminationAgreementPowerCapacityRightsAssignedToThirdParties / us-gaap_BusinessAcquisitionAxis = pnw_SouthernCaliforniaEdisonCompanyMember / us-gaap_JointlyOwnedUtilityPlantAxis = pnw_FourCornersUnits4And5Member / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember |
Capacity rights related to marketing and trading group for transmission of the additional power received assign to third-parties |  | 300 pnw_TransmissionTerminationAgreementPowerCapacityRightsRelatedToMarketingAndTradingGroupForTransmissionOfAdditionalPowerReceiveAssignedToThirdParties / us-gaap_BusinessAcquisitionAxis = pnw_SouthernCaliforniaEdisonCompanyMember / us-gaap_JointlyOwnedUtilityPlantAxis = pnw_FourCornersUnits4And5Member / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember |
Four Corners cost deferral | SCE | Four Corners Units 4 and 5 |  |  |
Business Acquisition [Line Items] |  |  |
Regulatory assets, non-current |  |  | 75 us-gaap_RegulatoryAssets / us-gaap_BusinessAcquisitionAxis = pnw_SouthernCaliforniaEdisonCompanyMember / us-gaap_JointlyOwnedUtilityPlantAxis = pnw_FourCornersUnits4And5Member / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember / us-gaap_RegulatoryAssetAxis = pnw_FourCornersCostDeferralMember
Regulatory noncurrent asset amortization period |  |  | 10 years
Retired power plant costs |  |  |
Business Acquisition [Line Items] |  |  |
Net book value |  |  | $ 127 pnw_RegulatoryAssetNetBookValue / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember / us-gaap_RegulatoryAssetAxis = pnw_RetiredPowerPlantCostsMember

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- Definition Represents the capacity rights over the Arizona Transmission System assigned to third-parties under negotiation of alternate arrangement. + References No definition available. + Details
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- Definition The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382 + Details
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