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Derivative Accounting Schedule of Gross Notional Amounts Outstanding (Details) | Mar. 31, 2015 GW
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Commodity - Power |
Outstanding gross notional amount of derivatives |
Outstanding gross notional amount of derivative instruments | 4,186 pnw_NonmonetaryNotionalAmountOfPriceRiskCashFlowHedgeDerivatives1 / us-gaap_DerivativeByNatureAxis = pnw_PowerMember
Commodity - Gas |
Outstanding gross notional amount of derivatives |
Outstanding gross notional amount of derivative instruments | 157,000 pnw_NonmonetaryNotionalAmountOfPriceRiskCashFlowHedgeDerivatives2 / us-gaap_DerivativeByNatureAxis = us-gaap_NaturalGasReservesMember

X
- Definition Aggregate notional amounts of price risk derivatives designated as a cash flow hedge with notional amounts expressed in a nonmonetary unit. For example the number of barrels specified in a fuel oil forward purchase contract. + References No definition available. + Details
Name: | pnw_NonmonetaryNotionalAmountOfPriceRiskCashFlowHedgeDerivatives1
Namespace Prefix: | pnw_
Data Type: | num:powerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Aggregate notional amount of price risk derivatives designated as a cash flow hedge with a notional amounts expressed in nonmonetary units. For example the number of barrels specified in a fuel oil forward purchase contract. + References No definition available. + Details
Name: | pnw_NonmonetaryNotionalAmountOfPriceRiskCashFlowHedgeDerivatives2
Namespace Prefix: | pnw_
Data Type: | num:volumeItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_NotionalAmountOfDerivativesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_DerivativeByNatureAxis=pnw_PowerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeByNatureAxis=us-gaap_NaturalGasReservesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |