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Nuclear Decommissioning Trusts (Details) (USD $) | 3 Months Ended |
--- | --- | ---
Mar. 31, 2015 | Mar. 31, 2014 | Dec. 31, 2014
Nuclear decommissioning trust fund assets |  |  |
Fair Value | $ 727,342,000 us-gaap_DecommissioningTrustAssetsAmount |  | $ 713,866,000 us-gaap_DecommissioningTrustAssetsAmount
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds |  |  |
Proceeds from the sale of securities | 115,282,000 us-gaap_ProceedsFromDecommissioningFund | 103,157,000 us-gaap_ProceedsFromDecommissioningFund |
Fair value of fixed income securities, summarized by contractual maturities |  |  |
Total | 727,342,000 us-gaap_DecommissioningTrustAssetsAmount |  | 713,866,000 us-gaap_DecommissioningTrustAssetsAmount
Arizona Public Service Company |  |  |
Nuclear decommissioning trust fund assets |  |  |
Fair Value | 727,342,000 us-gaap_DecommissioningTrustAssetsAmount / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember |  | 713,866,000 us-gaap_DecommissioningTrustAssetsAmount / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember
Unrealized Gains | 181,000,000 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember |  | 176,000,000 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember
Unrealized Losses | (1,000,000)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember |  | (1,000,000)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember
Net payables for securities purchases | (2,000,000)us-gaap_OtherPayablesToBrokerDealersAndClearingOrganizations / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember |  | (7,000,000)us-gaap_OtherPayablesToBrokerDealersAndClearingOrganizations / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds |  |  |
Realized gains | 1,000,000 us-gaap_AvailableForSaleSecuritiesGrossRealizedGains / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember | 1,000,000 us-gaap_AvailableForSaleSecuritiesGrossRealizedGains / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember |
Realized losses | (1,000,000)us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember | (2,000,000)us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember |
Proceeds from the sale of securities | 115,282,000 us-gaap_ProceedsFromDecommissioningFund / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember | 103,157,000 us-gaap_ProceedsFromDecommissioningFund / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember |
Fair value of fixed income securities, summarized by contractual maturities |  |  |
Total | 727,342,000 us-gaap_DecommissioningTrustAssetsAmount / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember |  | 713,866,000 us-gaap_DecommissioningTrustAssetsAmount / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember
Arizona Public Service Company | Equity Securities |  |  |
Nuclear decommissioning trust fund assets |  |  |
Fair Value | 313,000,000 us-gaap_DecommissioningTrustAssetsAmount / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember |  | 310,000,000 us-gaap_DecommissioningTrustAssetsAmount / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember
Unrealized Gains | 161,000,000 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember |  | 159,000,000 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember
Fair value of fixed income securities, summarized by contractual maturities |  |  |
Total | 313,000,000 us-gaap_DecommissioningTrustAssetsAmount / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember |  | 310,000,000 us-gaap_DecommissioningTrustAssetsAmount / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember
Arizona Public Service Company | Fixed income securities. |  |  |
Nuclear decommissioning trust fund assets |  |  |
Fair Value | 416,000,000 us-gaap_DecommissioningTrustAssetsAmount / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember |  | 411,000,000 us-gaap_DecommissioningTrustAssetsAmount / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember
Unrealized Gains | 20,000,000 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember |  | 17,000,000 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember
Unrealized Losses | (1,000,000)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember |  | (1,000,000)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember
Fair value of fixed income securities, summarized by contractual maturities |  |  |
Less than one year | 16,000,000 us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember |  |
1 year - 5 years | 113,000,000 us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember |  |
5 years - 10 years | 118,000,000 us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember |  |
Greater than 10 years | 169,000,000 us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember |  |
Total | $ 416,000,000 us-gaap_DecommissioningTrustAssetsAmount / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember |  | $ 411,000,000 us-gaap_DecommissioningTrustAssetsAmount / dei_LegalEntityAxis = pnw_ArizonaPublicServiceCompanyMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember

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- Definition The fair value of investments held in a trust fund to pay for the costs of decontaminating and decommissioning facilities, whether such amount is presented as a separate caption or as a parenthetical disclosure on the balance sheet. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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