XML 60 R44.htm IDEA: XBRL DOCUMENT
v3.19.1

Regulatory Matters - Cost Recovery Mechanism and Net Metering (Details) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 Months Ended | 12 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Apr. 10, 2019 USD ($) | Feb. 15, 2019 USD ($) | Feb. 01, 2019 $ / kWh | Aug. 13, 2018 USD ($) | Jun. 01, 2018 USD ($) | May 01, 2018 $ / kWh | Feb. 20, 2018 | Feb. 15, 2018 USD ($) | Feb. 01, 2018 $ / kWh | Jan. 08, 2018 USD ($) | Nov. 20, 2017 USD ($) | Aug. 19, 2017 $ / kWh | Jun. 01, 2017 USD ($) | Feb. 01, 2017 $ / kWh | Jan. 13, 2017 USD ($) | Dec. 20, 2016 $ / kWh | Feb. 01, 2016 $ / kWh | Mar. 31, 2019 USD ($) | Mar. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) $ / kWh | Dec. 31, 2012 $ / kWh | Dec. 31, 2018 USD ($) | Jun. 29, 2018 USD ($) | Nov. 14, 2017 USD ($) | Sep. 01, 2017 USD ($) | Jun. 30, 2017 USD ($)
Change in regulatory asset |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Deferred fuel and purchased power costs — current period |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ (16,709,000) | $ 18,950,000 |  |  |  |  |  |  |
Amounts charged to customers |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (12,872,000) | (20,002,000) |  |  |  |  |  |  |
Ballot Initiative, proposed required energy supply from renewable sources (as a percent) |  |  |  |  |  |  | 50.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
APS |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Change in regulatory asset |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Deferred fuel and purchased power costs — current period |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (16,709,000) | 18,950,000 |  |  |  |  |  |  |
Amounts charged to customers |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ (12,872,000) | (20,002,000) |  |  |  |  |  |  |
Lost Fixed Cost Recovery Mechanisms | APS |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Change in regulatory asset |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fixed costs recoverable per residential power lost (in dollars per kWh) | $ / kWh |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.031 |  |  |  |  |
Fixed costs recoverable per non-residential power lost (in dollars per kWh) | $ / kWh |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.023 |  |  |  |  |
Fixed cost recoverable per power lost (in dollars per kWh) | $ / kWh |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.025 |  |  |  |  |  |
Percentage of retail revenues |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.00% |  |  |  |  |  |  |  |
Amount of adjustment representing prorated sales losses approval |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 63,700,000 |  |  |  |  |  |  |  |  |  |  |
Increase (decrease) in amount of adjustment representing prorated sales losses |  | $ (24,500,000) |  |  |  |  |  | $ (3,000,000) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount of adjustment representing prorated sales losses pending approval |  | $ 36,200,000 |  |  |  |  |  | $ 60,700,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
ACC | APS |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Change in regulatory asset |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gross-up for revenue requirement of rate regulation |  |  |  | $ 86,500,000 |  |  |  |  |  | $ 119,100,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
ACC | RES | APS |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Settlement Agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Plan term |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5 years |  |  |  |  |  |  |  |
ACC | RES 2018 | APS |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Settlement Agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount of proposed budget |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 89,900,000 |  |  | $ 90,000,000
ACC | RES 2018 | APS | Solar Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Change in regulatory asset |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Program term |  |  |  |  |  |  |  |  |  |  | 3 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
ACC | Demand Side Management Adjustor Charge 2018 | APS |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Settlement Agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount of proposed budget |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 34,100,000 |  | $ 52,600,000 | $ 52,600,000 |
ACC | Power Supply Adjustor (PSA) | APS |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Change in regulatory asset |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Beginning balance |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 37,164,000 | 75,637,000 |  |  |  |  |  |  |
Deferred fuel and purchased power costs — current period |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (16,709,000) | 18,950,000 |  |  |  |  |  |  |
Amounts charged to customers |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (12,872,000) | (20,002,000) |  |  |  |  |  |  |
Ending balance |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7,583,000 | $ 74,585,000 | $ 75,637,000 |  |  |  |  |  |
PSA rate (in dollars per kWh) | $ / kWh |  |  | 0.001658 |  |  |  |  |  | 0.004555 |  |  | 0.000555 |  | (0.001348) |  |  |  |  |  |  |  |  |  |  |  |
Forward component of increase in PSA (in dollars per kWh) | $ / kWh |  |  | 0.000536 |  |  |  |  |  | 0.002009 |  |  | 0.000876 |  | (0.001027) |  |  |  |  |  |  |  |  |  |  |  |
Historical component of increase in PSA (in dollars per kWh) | $ / kWh |  |  | 0.001122 |  |  |  |  |  | 0.002546 |  |  | (0.000321) |  | (0.000321) |  |  |  |  |  |  |  |  |  |  |  |
Maximum increase (decrease) in PSA rate | $ / kWh |  |  |  |  |  |  |  |  | 0.004 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fuel and purchased power costs, excess annual limit |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 16,400,000 |  |  |  |  |  |  |  |
ACC | Net Metering | APS |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Change in regulatory asset |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cost of service, resource comparison proxy method, maximum annual percentage decrease |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.00% |  |  |  |  |  |  |  |  |  |
Cost of service for interconnected DG system customers, grandfathered period |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 20 years |  |  |  |  |  |  |  |  |  |
Cost of service for new customers, guaranteed export price period |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10 years |  |  |  |  |  |  |  |  |  |
First-year export energy price (in dollars per kWh) | $ / kWh |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.129 |  |  |  |  |  |  |  |  |  |
Second-year export energy price (in dollars per kWh) | $ / kWh |  |  |  |  |  | 0.116 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
United States Federal Energy Regulatory Commission | Open Access Transmission Tariff | APS |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Change in regulatory asset |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Increase (decrease) in annual wholesale transmission rates |  |  |  |  | $ (22,700,000) |  |  |  |  |  |  |  | $ 35,100,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Cost Recovery Mechanisms | ACC | Power Supply Adjustor (PSA) | APS |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Change in regulatory asset |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PSA rate for prior year (in dollars per kWh) | $ / kWh |  |  | (0.002897) |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.001678 |  |  |  |  |  |  |  |  |
Minimum | ACC | RES 2018 | APS | Solar Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Change in regulatory asset |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Required annual capital investment |  |  |  |  |  |  |  |  |  |  | $ 10,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum | ACC | RES 2018 | APS | Solar Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Change in regulatory asset |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Required annual capital investment |  |  |  |  |  |  |  |  |  |  | $ 15,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event | ACC | APS |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Change in regulatory asset |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gross-up for revenue requirement of rate regulation | $ 34,500,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Deferred taxes amortization, period | 28 years 6 months |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

X
- Definition Amount of Adjustment Representing Prorated Sales Losses Approved + References No definition available. + Details
Name: | pnw_AmountofAdjustmentRepresentingProratedSalesLossesApproved
Namespace Prefix: | pnw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of Adjustment Representing Prorated Sales Losses Pending Approval + References No definition available. + Details
Name: | pnw_AmountofAdjustmentRepresentingProratedSalesLossesPendingApproval
Namespace Prefix: | pnw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | pnw_DeferredFuelAndPurchasedPowerRegulatoryAssetLiabilityRollForward
Namespace Prefix: | pnw_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Deferred Fuel and Purchased Power Regulatory Asset (Liability), Current + References No definition available. + Details
Name: | pnw_DeferredFuelandPurchasedPowerRegulatoryAssetLiabilityCurrent
Namespace Prefix: | pnw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Represents the forward component of increase in PSA. + References No definition available. + Details
Name: | pnw_ForwardComponentOfPSARate
Namespace Prefix: | pnw_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fuel And Purchased Power Costs, Excess Annual Limit + References No definition available. + Details
Name: | pnw_FuelAndPurchasedPowerCostsExcessAnnualLimit
Namespace Prefix: | pnw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Represents the historical component of increase in PSA. + References No definition available. + Details
Name: | pnw_HistoricalComponentOfPSARate
Namespace Prefix: | pnw_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amortization of deferred fuel and purchased power costs. + References No definition available. + Details
Name: | pnw_IncreaseDecreaseDeferredFuelAndPurchasedPowerAmortization
Namespace Prefix: | pnw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Increase (Decrease) in Amount of Adjustment Representing Prorated Sales Losses + References No definition available. + Details
Name: | pnw_IncreaseDecreaseinAmountofAdjustmentRepresentingProratedSalesLosses
Namespace Prefix: | pnw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Maximum Increase Decrease in PSA Rate + References No definition available. + Details
Name: | pnw_MaximumIncreaseDecreaseinPSARate
Namespace Prefix: | pnw_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the PSA rate (power supply adjustor) which provides for the adjustment of retail rates to reflect variations in retail fuel and purchased power costs. + References No definition available. + Details
Name: | pnw_PSARate
Namespace Prefix: | pnw_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the PSA rate prior for the prior years (power supply adjustor) which provides for the adjustment of retail rates to reflect variations in retail fuel and purchased power costs. + References No definition available. + Details
Name: | pnw_PSARateInPriorYears
Namespace Prefix: | pnw_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | duration

X
- Definition Public Utilities, Ballot Initiative, Proposed Required Energy Supply From Renewable Sources, Percent + References No definition available. + Details
Name: | pnw_PublicUtilitiesBallotInitiativeProposedRequiredEnergySupplyFromRenewableSourcesPercent
Namespace Prefix: | pnw_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Public Utilities, Program Term + References No definition available. + Details
Name: | pnw_PublicUtilitiesProgramTerm
Namespace Prefix: | pnw_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Public Utilities, Requested Rate Increase (Decrease), Amount, Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Provisional Income Tax Expense (Benefit) + References No definition available. + Details
Name: | pnw_PublicUtilitiesRequestedRateIncreaseDecreaseAmountTaxCutsandJobsActof2017IncompleteAccountingProvisionalIncomeTaxExpenseBenefit
Namespace Prefix: | pnw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Public Utilities, Requested Rate Increase (Decrease), Deferred Taxes Amortization, Period + References No definition available. + Details
Name: | pnw_PublicUtilitiesRequestedRateIncreaseDecreaseDeferredTaxesAmortizationPeriod
Namespace Prefix: | pnw_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Public Utilities, Required Annual Capital Investment + References No definition available. + Details
Name: | pnw_PublicUtilitiesRequiredAnnualCapitalInvestment
Namespace Prefix: | pnw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Represents information pertaining to cap percentage of retail revenues. + References No definition available. + Details
Name: | pnw_RateMatterCapPercentageOfRetailRevenue
Namespace Prefix: | pnw_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents fixed costs recovered by the LFCR mechanism per non-residential kWh lost. + References No definition available. + Details
Name: | pnw_RateMatterFixedCostRecoverablePerNonResidentialPowerLost
Namespace Prefix: | pnw_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | duration

X
- Definition Rate Matter, Fixed Cost Recoverable Per Power Lost + References No definition available. + Details
Name: | pnw_RateMatterFixedCostRecoverablePerPowerLost
Namespace Prefix: | pnw_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents fixed costs recovered by the LFCR mechanism per residential kWh lost. + References No definition available. + Details
Name: | pnw_RateMatterFixedCostRecoverablePerResidentialPowerLost
Namespace Prefix: | pnw_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | duration

X
- Definition The period of time covered by a plan to implement a standard enacted by a regulatory authority. + References No definition available. + Details
Name: | pnw_RateMatterPlanTerm
Namespace Prefix: | pnw_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the amount of proposed budget. + References No definition available. + Details
Name: | pnw_RateMatterProposedBudget
Namespace Prefix: | pnw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Rate Matter, Request Second-Year Energy Price for Exported Energy + References No definition available. + Details
Name: | pnw_RateMatterRequestSecondYearEnergyPriceforExportedEnergy
Namespace Prefix: | pnw_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | duration

X
- Definition Rate Matter, Settlement Agreement, Energy Price for Exported Energy + References No definition available. + Details
Name: | pnw_RateMatterSettlementAgreementEnergyPriceforExportedEnergy
Namespace Prefix: | pnw_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | duration

X
- Definition Rate Matters, Cost of Service, Resource Comparison Proxy Method, Maximum Annual Percentage Decrease + References No definition available. + Details
Name: | pnw_RateMattersCostofServiceResourceComparisonProxyMethodMaximumAnnualPercentageDecrease
Namespace Prefix: | pnw_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Rate Matters, Cost of Service for Interconnected DG System Customers, Grandfathered Period + References No definition available. + Details
Name: | pnw_RateMattersCostofServiceforInterconnectedDGSystemCustomersGrandfatheredPeriod
Namespace Prefix: | pnw_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Rate Matters, Cost of Service for New Customers, Guaranteed Export Price Period + References No definition available. + Details
Name: | pnw_RateMattersCostofServiceforNewCustomersGuaranteedExportPricePeriod
Namespace Prefix: | pnw_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Rate Matters, Increase (Decrease) in Cost Recovery + References No definition available. + Details
Name: | pnw_RateMattersIncreaseDecreaseinCostRecovery
Namespace Prefix: | pnw_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The increase (decrease) during the reporting period in unrecovered fuel costs for a regulated utility company. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585 + Details
Name: | us-gaap_IncreaseDecreaseInRegulatoryClauseRevenue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_PublicUtilitiesRateMattersApprovedAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=pnw_ArizonaPublicServiceCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilitiesRegulatoryProceedingAxis=pnw_LostFixedCostRecoveryMechanismsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RegulatoryAgencyAxis=pnw_ArizonaCorporationCommissionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilitiesRegulatoryProceedingAxis=pnw_ArizonaRenewableEnergyStandardAndTariffMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilitiesRegulatoryProceedingAxis=pnw_ArizonaRenewableEnergyStandardandTariff2018Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | pnw_PublicUtilityProgramAxis=pnw_SolarCommunitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilitiesRegulatoryProceedingAxis=pnw_DemandSideManagementAdjustorCharge2018Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilitiesRegulatoryProceedingAxis=pnw_PowerSupplyAdjustorMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilitiesRegulatoryProceedingAxis=pnw_NetMeteringMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RegulatoryAgencyAxis=pnw_UnitedStatesFederalEnergyRegulatoryCommissionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilitiesRegulatoryProceedingAxis=pnw_OpenAccessTransmissionTariffMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | pnw_PublicUtilitiesRegulatoryRegulatoryMattersAxis=pnw_CostRecoveryMechanismsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |