XML 58 R44.htm IDEA: XBRL DOCUMENT
v3.21.1

Regulatory Matters - Four Corners and Cholla (Details) - APS - USD ($) $ in Millions | 1 Months Ended |
--- | --- | ---
Sep. 30, 2018 | Apr. 30, 2018 | Mar. 31, 2021
SCE | Four Corners Units 4 and 5 |  |  |
Business Acquisition [Line Items] |  |  |
Settlement agreement, ACC approved rate adjustment, annualized customer impact | $ 58.5 | $ 67.5 |
Retired power plant costs |  |  |
Business Acquisition [Line Items] |  |  |
Net book value |  |  | $ 52.9
Navajo Plant |  |  |
Business Acquisition [Line Items] |  |  |
Net book value |  |  | 69.4
Navajo Plant, Coal Reclamation Regulatory Asset |  |  |
Business Acquisition [Line Items] |  |  |
Net book value |  |  | $ 17.8

X
- Definition Regulatory Asset, Net Book Value + References No definition available. + Details
Name: | pnw_RegulatoryAssetNetBookValue
Namespace Prefix: | pnw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Settlement agreement, ACC approved rate adjustment, annualized customer impact + References No definition available. + Details
Name: | pnw_SettlementagreementACCapprovedrateadjustmentannualizedcustomerimpact
Namespace Prefix: | pnw_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_BusinessAcquisitionLineItems
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_BusinessAcquisitionAxis=pnw_SouthernCaliforniaEdisonCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_JointlyOwnedUtilityPlantAxis=pnw_FourCornersUnits4And5Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RegulatoryAssetAxis=pnw_RetiredPowerPlantCostsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RegulatoryAssetAxis=pnw_NavajoPlantMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RegulatoryAssetAxis=pnw_NavajoPlantCoalReclamationRegulatoryAssetMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |