XML 68 R55.htm IDEA: XBRL DOCUMENT
v3.20.2

Retirement Plans and Other Postretirement Benefits - Narrative (Details) | 9 Months Ended
--- | ---
Sep. 30, 2020 USD ($)
Pension Benefits |
Contributions |
Voluntary contributions | $ 100,000,000
Minimum employer contributions for the next three years | 0
Maximum employer contributions for the next two years (up to) | 100,000,000
Other Benefits |
Contributions |
Estimated future employer contributions in next three years | $ 0

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

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

X
- Definition Defined Benefit Plans Estimated Maximum Future Employer Contributions, Per Year Maximum Contribution For The Next Three Fiscal Years + References No definition available. + Details
Name: | pnw_DefinedBenefitPlansEstimatedMaximumFutureEmployerContributionsPerYearMaximumContributionForTheNextThreeFiscalYears
Namespace Prefix: | pnw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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

X
- Definition Defined Benefit Plans, Voluntary Contributions + References No definition available. + Details
Name: | pnw_DefinedBenefitPlansVoluntaryContributions
Namespace Prefix: | pnw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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

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