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Retirement Plans and Other Postretirement Benefits - Narrative (Details) $ in Millions | 3 Months Ended
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Mar. 31, 2022 USD ($)
Pension Benefits |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |
Minimum employer contributions for the next three years | $ 0

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- Definition Defined Benefit Plans Estimated Minimum Future Employer Contributions, Next Three Fiscal Years + References No definition available. + Details
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Namespace Prefix: | pnw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- 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
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |