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Commitments and Contingencies - Environmental Matters and Financial Assurances (Details) (USD $)
3 Months Ended 0 Months Ended
Mar. 31, 2015
May 23, 2013
Arizona Public Service Company | Four Corners Units 4 and 5    
Environmental Matters    
Percentage of share of cost of control 63.00%pnw_PercentageOfShareOfCostOfControl
/ us-gaap_JointlyOwnedUtilityPlantAxis
= pnw_FourCornersUnits4And5Member
/ dei_LegalEntityAxis
= pnw_ArizonaPublicServiceCompanyMember
 
Expected environmental cost $ 400,000,000us-gaap_SiteContingencyLossExposureNotAccruedBestEstimate
/ us-gaap_JointlyOwnedUtilityPlantAxis
= pnw_FourCornersUnits4And5Member
/ dei_LegalEntityAxis
= pnw_ArizonaPublicServiceCompanyMember
 
Cholla | Arizona Public Service Company    
Environmental Matters    
Expected environmental cost 200,000,000us-gaap_SiteContingencyLossExposureNotAccruedBestEstimate
/ us-gaap_EnvironmentalRemediationSiteAxis
= pnw_ChollaMember
/ dei_LegalEntityAxis
= pnw_ArizonaPublicServiceCompanyMember
 
Site contingency increase in loss exposure not accrued, best estimate 85,000,000pnw_AssetPurchaseAgreementSiteContingencyIncreaseinLossExposureNotAccruedBestEstimate
/ us-gaap_EnvironmentalRemediationSiteAxis
= pnw_ChollaMember
/ dei_LegalEntityAxis
= pnw_ArizonaPublicServiceCompanyMember
 
Four Corners | New Mexico Tax Matter    
Environmental Matters    
Coal severance surtax, penalty, and interest   30,000,000pnw_LossContingencyCoalSeveranceSurtaxPenaltyAndInterest
/ us-gaap_EnvironmentalRemediationSiteAxis
= pnw_FourCornersMember
/ us-gaap_LitigationCaseAxis
= pnw_NewMexicoTaxMatterMember
Four Corners | Arizona Public Service Company    
Environmental Matters    
Site contingency increase in loss exposure not accrued, best estimate 15,000,000pnw_AssetPurchaseAgreementSiteContingencyIncreaseinLossExposureNotAccruedBestEstimate
/ us-gaap_EnvironmentalRemediationSiteAxis
= pnw_FourCornersMember
/ dei_LegalEntityAxis
= pnw_ArizonaPublicServiceCompanyMember
 
Four Corners | Arizona Public Service Company | Four Corners Units 4 and 5    
Environmental Matters    
Site contingency increase in loss exposure not accrued, best estimate 45,000,000pnw_AssetPurchaseAgreementSiteContingencyIncreaseinLossExposureNotAccruedBestEstimate
/ us-gaap_EnvironmentalRemediationSiteAxis
= pnw_FourCornersMember
/ us-gaap_JointlyOwnedUtilityPlantAxis
= pnw_FourCornersUnits4And5Member
/ dei_LegalEntityAxis
= pnw_ArizonaPublicServiceCompanyMember
 
Four Corners | Arizona Public Service Company | New Mexico Tax Matter    
Environmental Matters    
Share of the assessment   12,000,000pnw_LossContingencyAssessmentShare
/ us-gaap_EnvironmentalRemediationSiteAxis
= pnw_FourCornersMember
/ dei_LegalEntityAxis
= pnw_ArizonaPublicServiceCompanyMember
/ us-gaap_LitigationCaseAxis
= pnw_NewMexicoTaxMatterMember
Navajo Plant | Arizona Public Service Company    
Environmental Matters    
Expected environmental cost 200,000,000us-gaap_SiteContingencyLossExposureNotAccruedBestEstimate
/ us-gaap_EnvironmentalRemediationSiteAxis
= pnw_NavajoGeneratingStationMember
/ dei_LegalEntityAxis
= pnw_ArizonaPublicServiceCompanyMember
 
Site contingency increase in loss exposure not accrued, best estimate 1,000,000pnw_AssetPurchaseAgreementSiteContingencyIncreaseinLossExposureNotAccruedBestEstimate
/ us-gaap_EnvironmentalRemediationSiteAxis
= pnw_NavajoGeneratingStationMember
/ dei_LegalEntityAxis
= pnw_ArizonaPublicServiceCompanyMember
 
Cholla Units 2 And 3 | Arizona Public Service Company    
Environmental Matters    
Expected environmental cost 130,000,000us-gaap_SiteContingencyLossExposureNotAccruedBestEstimate
/ us-gaap_EnvironmentalRemediationSiteAxis
= pnw_ChollaUnits2And3Member
/ dei_LegalEntityAxis
= pnw_ArizonaPublicServiceCompanyMember
 
Letter of Credit | Arizona Public Service Company    
Financial Assurances    
Outstanding letters of credit 109,000,000us-gaap_LettersOfCreditOutstandingAmount
/ us-gaap_CreditFacilityAxis
= us-gaap_LetterOfCreditMember
/ dei_LegalEntityAxis
= pnw_ArizonaPublicServiceCompanyMember
 
Equity Lessors in Palo Verde sale leaseback transactions | Arizona Public Service Company    
Financial Assurances    
Outstanding letters of credit 20,000,000us-gaap_LettersOfCreditOutstandingAmount
/ us-gaap_CreditFacilityAxis
= pnw_EquityLessorsSaleLeasebackLetterOfCreditMember
/ dei_LegalEntityAxis
= pnw_ArizonaPublicServiceCompanyMember
 
Natural gas tolling contract obligations | Arizona Public Service Company    
Financial Assurances    
Outstanding letters of credit $ 5,000,000us-gaap_LettersOfCreditOutstandingAmount
/ us-gaap_CreditFacilityAxis
= pnw_NaturalGasTollingLetterOfCreditMember
/ dei_LegalEntityAxis
= pnw_ArizonaPublicServiceCompanyMember
 
Natural gas tolling contract obligations | Arizona Public Service Company | Four Corners Units 4 and 5    
Environmental Matters    
Additional percentage share of cost of control 7.00%pnw_AssetPurchaseAgreementAdditionalPercentageShareofCostofControl
/ us-gaap_CreditFacilityAxis
= pnw_NaturalGasTollingLetterOfCreditMember
/ us-gaap_JointlyOwnedUtilityPlantAxis
= pnw_FourCornersUnits4And5Member
/ dei_LegalEntityAxis
= pnw_ArizonaPublicServiceCompanyMember
 
Letters of Credit Expiring in 2015 | Arizona Public Service Company    
Financial Assurances    
Number of letters of credit expiring 1pnw_NumberOfLettersOfCreditExpiring
/ us-gaap_DebtInstrumentAxis
= pnw_LettersOfCreditExpiringIn2015Member
/ dei_LegalEntityAxis
= pnw_ArizonaPublicServiceCompanyMember
 
Letters of Credit Expiring in 2016 | Arizona Public Service Company    
Financial Assurances    
Number of letters of credit expiring 2pnw_NumberOfLettersOfCreditExpiring
/ us-gaap_DebtInstrumentAxis
= pnw_LettersOfCreditExpiringIn2016Member
/ dei_LegalEntityAxis
= pnw_ArizonaPublicServiceCompanyMember