XML 1086 R61.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Regulatory Matters - Schedule of Regulatory Assets (Details) - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Detail of regulatory assets |  |
Regulatory assets, current | $ 248,088 | $ 106,875
Regulatory assets, non-current | 1,202,302 | 1,313,428
Pension |  |
Detail of regulatory assets |  |
Regulatory assets, current | 0 | 0
Regulatory assets, non-current | 576,188 | 711,059
Retired power plant costs |  |
Detail of regulatory assets |  |
Regulatory assets, current | 27,402 | 9,913
Regulatory assets, non-current | 188,843 | 117,591
Income taxes - AFUDC equity |  |
Detail of regulatory assets |  |
Regulatory assets, current | 3,828 | 6,305
Regulatory assets, non-current | 142,852 | 152,118
Deferred fuel and purchased power - mark-to-market |  |
Detail of regulatory assets |  |
Regulatory assets, current | 52,100 | 0
Regulatory assets, non-current | 34,845 | 42,963
Four Corners cost deferral |  |
Detail of regulatory assets |  |
Regulatory assets, current | 8,077 | 6,689
Regulatory assets, non-current | 48,305 | 56,894
Income taxes — investment tax credit basis adjustment |  |
Detail of regulatory assets |  |
Regulatory assets, current | 1,066 | 2,120
Regulatory assets, non-current | 26,218 | 54,356
Lost fixed cost recovery |  |
Detail of regulatory assets |  |
Regulatory assets, current | 59,844 | 61,307
Regulatory assets, non-current | 0 | 0
Palo Verde VIE |  |
Detail of regulatory assets |  |
Regulatory assets, current | 0 | 0
Regulatory assets, non-current | 19,395 | 18,775
Deferred compensation |  |
Detail of regulatory assets |  |
Regulatory assets, current | 0 | 0
Regulatory assets, non-current | 36,413 | 35,595
Deferred property taxes |  |
Detail of regulatory assets |  |
Regulatory assets, current | 8,569 | 0
Regulatory assets, non-current | 74,926 | 73,200
Loss on reacquired debt |  |
Detail of regulatory assets |  |
Regulatory assets, current | 1,637 | 1,637
Regulatory assets, non-current | 15,305 | 16,942
AG-1 deferral |  |
Detail of regulatory assets |  |
Regulatory assets, current | 2,654 | 0
Regulatory assets, non-current | 8,472 | 5,868
Demand side management |  |
Detail of regulatory assets |  |
Regulatory assets, current | 0 | 3,744
Regulatory assets, non-current | 0 | 0
Tax expense of Medicare subsidy |  |
Detail of regulatory assets |  |
Regulatory assets, current | 1,236 | 1,513
Regulatory assets, non-current | 7,415 | 10,589
Mead-Phoenix transmission line CIAC |  |
Detail of regulatory assets |  |
Regulatory assets, current | 332 | 332
Regulatory assets, non-current | 10,376 | 10,708
Deferred fuel and purchased power |  |
Detail of regulatory assets |  |
Regulatory assets, current | 75,637 | 12,465
Regulatory assets, non-current | 0 | 0
Coal reclamation |  |
Detail of regulatory assets |  |
Regulatory assets, current | 1,068 | 418
Regulatory assets, non-current | 12,396 | 5,182
Other |  |
Detail of regulatory assets |  |
Regulatory assets, current | 4,638 | 432
Regulatory assets, non-current | $ 353 | $ 1,588

X
- Definition The amount for the individual regulatory current asset including deferred fuel and purchased power as itemized in a table of regulatory current assets as of the end of the period. + References No definition available. + Details
Name: | pnw_RegulatoryAssetIncludingDeferredFuelAndPurchasedPowerRegulatoryAssetCurrent
Namespace Prefix: | pnw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

X
- Definition Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are not expected to be recovered through revenue sources within one year or the normal operating cycle if longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382 + Details
Name: | us-gaap_RegulatoryAssetsNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

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

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

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

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

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

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

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

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

X
- Details
Name: | us-gaap_RegulatoryAssetAxis=pnw_AG1DeferralMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

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

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

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

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