Derivative Instruments and Hedging Activities Disclosure [Abstract] Offsetting Assets and Liabilities [Table] Offsetting Assets and Liabilities [Table] Disclosure of information about derivatives, financial assets and liabilities that are subject to offsetting, including enforceable master netting arrangements. Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Commodity Contracts Commodity Contract [Member] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Current Assets Other Assets [Member] Investments and Other Assets Other Investments [Member] Current Liabilities Other Liabilities [Member] Deferred Credits and Other Deferred Credits [Member] Line item in the statement of financial position in which the fair value amounts of the derivative instruments are included. Fair value of risk management activities reported on gross basis and the impacts of offsetting Offsetting Assets and Liabilities [Line Items] Assets Offsetting Derivative Assets [Abstract] Gross Recognized Derivatives Derivative Asset, Fair Value, Gross Asset Amounts Offset Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset Net Recognized Derivatives Derivative Asset, Fair Value, Amount Not Offset Against Collateral Other Derivative Asset, Not Subject to Master Netting Arrangement Amount Reported on Balance Sheet Derivative Asset Liabilities Offsetting Derivative Liabilities [Abstract] Gross Recognized Derivatives Derivative Liability, Fair Value, Gross Liability Amounts Offset Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset Net Recognized Derivatives Derivative Liability, Fair Value, Amount Not Offset Against Collateral Other Derivative Liability, Not Subject to Master Netting Arrangement Amount Reported on Balance Sheet Derivative Liability Assets and Liabilities Offsetting Derivative Assets Liabilities, Net [Abstract] Gross Recognized Derivatives Derivative Asset (Liability), Fair Value, Gross Asset (Liability) Represents the fair value of derivative asset, net of liability, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position. Amounts Offset Derivative Asset (Liability), Fair Value, Gross Liability (Asset) and Obligation to Return and Right to Reclaim Cash, Offset Derivative Asset (Liability), Fair Value, Gross Liability (Asset) and Obligation to Return and Right to Reclaim Cash, Offset Net Recognized Derivatives Derivative Asset (Liability), Fair Value, Amount Not Offset Against Collateral Derivative Asset (Liability), Fair Value, Amount Not Offset Against Collateral Other Derivative Asset (Liability), Amount Not Offset Against Collateral Derivative Asset (Liability), Amount Not Offset Against Collateral Amount Reported on Balance Sheet Derivative Assets (Liabilities), at Fair Value, Net Derivative Accounting Derivative Instruments and Hedging Activities Disclosure [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Summary of supplemental cash flow information Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Debt Disclosure [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Pinnacle West Parent Company [Member] Arizona Public Service Company Arizona Public Service Company [Member] Represents Arizona Public Service Company, which is an electric utility subsidiary of the entity. Long-Term Debt and Liquidity Matters Debt Instrument [Line Items] Estimated fair value of long-term debt, including current maturities Debt Instruments [Abstract] Carrying Amount Debt and Capital Lease Obligations Fair Value Long-term Debt, Fair Value Investments, Debt and Equity Securities [Abstract] Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Domain] Major Types of Debt and Equity Securities [Domain] Equity Securities Equity Securities [Member] Fixed income securities. Fixed Income Securities [Member] Nuclear decommissioning trust fund assets Schedule of Available-for-sale Securities [Line Items] Fair Value Decommissioning Fund Investments, Fair Value Unrealized Gains Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax Unrealized Losses Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax Net payables for securities purchases Other Payables to Broker-Dealers and Clearing Organizations Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds Available-for-sale Securities, Gross Realized Gain (Loss), Disclosures [Abstract] Realized gains Available-for-sale Securities, Gross Realized Gains Realized losses Available-for-sale Securities, Gross Realized Losses Proceeds from the sale of securities Proceeds from Decommissioning Trust Fund Assets Fair value of fixed income securities, summarized by contractual maturities Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract] Less than one year Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value 1 year - 5 years Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value 5 years - 10 years Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value Greater than 10 years Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value Total Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Schedule of changes in accumulated other comprehensive loss including reclassification adjustments, net of tax, by component Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Fair Value Disclosures [Abstract] Fair Value Inputs, Liabilities, Quantitative Information [Table] Fair Value Inputs, Liabilities, Quantitative Information [Table] Liability Class [Axis] Liability Class [Axis] Fair Value by Liability Class [Domain] Fair Value by Liability Class [Domain] Electricity forward contracts Electricity Contracts [Member] Represents derivative instruments with primary underlying risk tied to electricity contracts. Option Contracts Commodity Option [Member] Natural gas forward contracts Natural Gas Contracts [Member] Represents derivative instruments with primary underlying risk tied to natural gas contracts. Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Weighted Average Weighted Average [Member] Valuation Technique [Axis] Valuation Technique [Axis] Valuation Technique [Domain] Valuation Technique [Domain] Discounted cash flows Market Approach Valuation Technique [Member] Option model Option Model Valuation Technique [Member] Option model valuation technique used to measure fair value. Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments Fair Value Inputs, Liabilities, Quantitative Information [Line Items] Assets Assets, Fair Value Disclosure Liabilities Financial and Nonfinancial Liabilities, Fair Value Disclosure Electricity forward price (per MWh) Fair Value Inputs, Electricity Forward Price Per Megawatt Hours Represents the electricity forward price per Megawatt Hours, used as an input to measure fair value. Electricity price volatilities (as a percent) Fair Value Inputs, Implied Electricity Volatilities Represents the percentage of implied electricity volatilities. Natural gas price volatilities (as a percent) Fair Value Inputs, Implied Gas Price Volatilities Represents the percentage of implied electricity natural gas price volatilities. Natural gas forward price (per MMbtu) Fair Value Inputs, Gas Forward Price Per Metric Million British Thermal Units Represents the gas price per Metric Million British Thermal Units, used as an input to measure fair value. Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock Common Stock [Member] Additional Paid-In Capital Additional Paid-in Capital [Member] Treasury Stock Treasury Stock [Member] Retained Earnings Retained Earnings [Member] Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Noncontrolling Interests Noncontrolling Interest [Member] Statement [Line Items] Statement [Line Items] Increase (Decrease) in Shareholders' Equity Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning balance (in shares) Common Stock, Shares, Issued Balance at end of period Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Other comprehensive income Other Comprehensive Income (Loss), Net of Tax Other Stockholders' Equity, Other Issuance of common stock (in shares) Stock Issued During Period, Shares, New Issues Issuance of common stock Stock Issued During Period, Value, New Issues Purchase of treasury stock (in shares) Treasury Stock, Shares, Acquired Purchase of treasury stock Treasury Stock, Value, Acquired, Cost Method Reissuance of treasury stock for stock-based compensation and other (in shares) Stock Issued During Period, Shares, Treasury Stock Reissued Reissuance of treasury stock for stock-based compensation and other Stock Issued During Period, Value, Treasury Stock Reissued Ending balance (in shares) Balance at beginning of period Fair value of APS's nuclear decommissioning trust fund assets Available-for-sale Securities [Table Text Block] Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds Schedule of Realized Gain (Loss) [Table Text Block] Fair value of fixed income securities, summarized by contractual maturities Investments Classified by Contractual Maturity Date [Table Text Block] Earnings Per Share [Abstract] Schedule of earnings per weighted average common share outstanding Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Regulated Operations [Abstract] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Environmental Remediation Site [Axis] Environmental Remediation Site [Axis] Environmental Remediation Site [Domain] Environmental Remediation Site [Domain] Four Corners Four Corners [Member] Represent information pertaining to Four Corners. Regulatory Asset [Axis] Regulatory Asset [Axis] Regulatory Asset [Domain] Regulatory Asset [Domain] Four Corners cost deferral (b) Four Corners Cost Deferral [Member] Represents the regulatory asset under Four Corners cost deferral. Retired power plant costs Retired Power Plant Costs [Member] Represents the regulatory asset under Retired power plant costs. APS Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] SCE Southern California Edison Company [Member] Represents information related to Southern California Edison Company. Jointly Owned Utility Plant [Axis] Jointly Owned Utility Plant [Axis] Jointly Owned Utility Plant [Domain] Jointly Owned Utility Plant [Domain] Four Corners Units 4 and 5 Four Corners Units 4 and 5 [Member] Represents Four Corners Units 4 and 5, a jointly-owned generating facility of the entity. Business Acquisition [Line Items] Business Acquisition [Line Items] Ownership interest acquired Business Acquisition, Percentage of Voting Interests Acquired Settlement agreement, ACC approved rate adjustment, annualized customer impact Settlement agreement, ACC approved rate adjustment, annualized customer impact Settlement agreement, ACC approved rate adjustment, annualized customer impact Regulatory assets, non-current Regulatory Assets Regulatory noncurrent asset amortization period Regulatory Asset, Noncurrent, Amortization Period Regulatory Asset, Noncurrent, Amortization Period Net receipt due to negotiation of alternate arrangement Transmission Termination Agreement Net Receipt Due to Negotiation of Alternate Arrangement Represents the amount of net receipt due to negotiation of alternate arrangement. Net book value Regulatory Asset, Net Book Value Regulatory Asset, Net Book Value Nuclear Decommissioning Trusts Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Derivative [Table] Derivative [Table] Derivative Accounting Derivative [Line Items] Outstanding gross notional amount of derivatives Notional Disclosures [Abstract] Power Derivative, Nonmonetary Notional Amount, Energy Measure Gas Derivative, Nonmonetary Notional Amount, Volume Compensation and Retirement Disclosure [Abstract] Schedule of net periodic benefit costs and the portion of these costs charged to expense (including administrative costs and excluding amounts capitalized as overhead construction, billed to electric plant participants or charged or amortized to the regulatory asset) Schedule of Net Benefit Costs [Table Text Block] Document and Entity Information Entities [Table] Entities [Table] Entity Information [Line Items] Entity Information [Line Items] Entity Registrant Name Entity Central Index Key Document Type Document Period End Date Amendment Flag Current Fiscal Year End Date Entity Current Reporting Status Entity Filer Category Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Period Focus Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plan and Other Postretirement Benefit Plan [Domain] Defined Benefit Plan and Other Postretirement Benefit Plan [Domain] Pension Benefits Pension Plan [Member] Other postretirement benefits Other Postretirement Benefit Plan [Member] Retirement Plans and Other Benefits Defined Benefit Plan Disclosure [Line Items] Service cost — benefits earned during the period Defined Benefit Plan, Service Cost Interest cost on benefit obligation Defined Benefit Plan, Interest Cost Expected return on plan assets Defined Benefit Plan, Expected Return on Plan Assets Amortization of: Amortization of Prior Service Cost and Net Actuarial Loss [Abstract] Amortization of Prior Service Cost and Net Actuarial Loss [Abstract] Prior service cost Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Net actuarial loss Defined Benefit Plan, Amortization of Gains (Losses) Net periodic benefit cost Defined Benefit Plan, Net Periodic Benefit Cost Portion of cost charged to expense Pension and Other Postretirement Benefit Expense Derivative Instruments, Gain (Loss) [Table] Derivative Instruments, Gain (Loss) [Table] Other Comprehensive Income Location [Axis] Other Comprehensive Income Location [Axis] Other Comprehensive Income Location [Domain] Other Comprehensive Income Location [Domain] Other comprehensive income Other Comprehensive Income (Loss) [Member] Hedging Designation [Axis] Hedging Designation [Axis] Hedging Designation [Domain] Hedging Designation [Domain] Designated as Hedging Instruments Designated as Hedging Instrument [Member] Not Designated as Hedging Instruments Not Designated as Hedging Instrument [Member] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Revenue Sales [Member] Fuel and purchased power Cost of Sales [Member] Gains and losses from derivative instruments Derivative Instruments, Gain (Loss) [Line Items] Loss recognized in OCI on derivative instruments (effective portion) Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net Loss reclassified from accumulated OCI into income (effective portion realized) Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net Amount reclassified from accumulated other comprehensive income to earnings related to discontinued cash flow hedges Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income on Discontinuation The net gain (loss) reclassified from accumulated other comprehensive income into income on discontinuation of derivative instruments designated and qualifying as hedging instruments. Gains and losses from derivative instruments Derivative, Gain (Loss) on Derivative, Net [Abstract] Net loss recognized in income Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net Statement of Comprehensive Income [Abstract] Net unrealized loss, tax expense Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax Reclassification of net realized loss, tax (expense) benefit Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax Pension and other postretirement benefits activity, tax expense Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax New Accounting Pronouncements and Changes in Accounting Principles [Abstract] New Accounting Standards New Accounting Pronouncements, Policy [Policy Text Block] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Revolving Credit Facility Revolving Credit Facility [Member] Letter of Credit Letter of Credit [Member] Commercial paper Commercial Paper [Member] Secured debt Term Loan [Member] Term Loan [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Term loan facility maturing April 22, 2019 Term Loan Facility Maturing April 22, 2019 [Member] Term Loan Facility Maturing April 22, 2019 [Member] Revolving Credit Facilities Maturing in 2020 and 2019 Revolving Credit Facilities Maturing in 2020 and 2019 [Member] Revolving Credit Facilities Maturing in 2020 and 2019 [Member] Revolving credit facility maturing September 2020 Revolving Credit Facility Maturing September 2020 [Member] Revolving Credit Facility Maturing September 2020 [Member] Revolving credit facility maturing in May 2019 Revolving Credit Facility Maturing May 2019 [Member] Revolving Credit Facility Maturing May 2019 [Member] Regulatory Agency [Axis] Regulatory Agency [Axis] Regulatory Agency [Domain] Regulatory Agency [Domain] ACC Arizona Corporation Commission [Member] Represents the Arizona Corporation Commission (ACC), which regulates public utilities in Arizona. Current borrowing capacity on credit facility Line of Credit Facility, Current Borrowing Capacity Maximum borrowing capacity on credit facility upon satisfaction of certain conditions and consent of lenders (up to) Line of Credit Facility, Maximum Borrowing Capacity Outstanding borrowings Long-term Line of Credit Outstanding letters of credit Letters of Credit Outstanding, Amount Commercial paper Commercial Paper Maximum commercial paper support available under credit facility Line of Credit Facility, Commercial Paper Program Maximum Borrowing Capacity Represents the maximum borrowings available for the commercial paper program under the terms of line of credit facility. Debt issued Debt Instrument, Face Amount Number of line of credit facilities Line of Credit Facility, Number of Agreements Represents the number of line of credit facilities. Debt Provisions Debt Provisions [Abstract] Required common equity ratio ordered by ACC (as a percent) (at least) Public Utility Order Common Stockholders Equity Ratio The common equity ratio (defined as the total shareholder equity divided by the sum of total shareholder equity and long-term debt, including current maturities of long-term debt), which the entity is required to maintain pursuant to an order from a regulatory authority. Total shareholder equity Stockholders' Equity Attributable to Parent Total capitalization Shareholder Equity and Long Term Debt and Current Maturities The sum of total shareholder equity and long-term debt less current maturities, including a portion of APS' current maturities of long-term debt. Dividend restrictions, shareholder equity required Public Utility Order Dividend Restrictions Shareholder Equity The amount of total shareholder equity required in order for the entity to pay dividends pursuant to an order from a regulatory authority. Net income attributable to common shareholders Net Income (Loss) Available to Common Stockholders, Basic Weighted average common shares outstanding - basic (in shares) Weighted Average Number of Shares Outstanding, Basic Net effect of dilutive securities: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Contingently issuable performance shares and restricted stock units (in shares) Weighted Average Number of Shares, Restricted Stock Weighted average common shares outstanding — diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Net income attributable to common shareholders - basic (in dollars per share) Earnings Per Share, Basic Net income attributable to common shareholders - diluted (in dollars per share) Earnings Per Share, Diluted New Accounting Standards New Accounting Pronouncements and Changes in Accounting Principles [Text Block] Commitments and Contingencies Disclosure [Abstract] Site Contingency [Table] Site Contingency [Table] Environmental Remediation Contingency [Axis] Environmental Remediation Contingency [Axis] Environmental Remediation Contingency [Domain] Environmental Remediation Contingency [Domain] Regional Haze Rules Regional Haze Rules [Member] Regional Haze Rules [Member] Mercury and air toxic standards (MATS) Mercury and Air Toxic Standards [Member] Mercury and Air Toxic Standards [Member] Coal combustion waste Coal Combustion Waste [Member] Coal Combustion Waste [Member] Navajo Plant Navajo Generating Station [Member] Represent information pertaining to Navajo Generating Station. Cholla Cholla [Member] Represent information pertaining to Cholla. Letter of Credit Natural gas tolling contract obligations Natural Gas Tolling Letter of Credit [Member] A document typically issued by a financial institution which acts as a guarantee of payment to a beneficiary, or as the source of payment for a specific transaction to natural gas tolling contract obligations as of the reporting date. Letters of Credit Expiring in 2017 Letters of Credit Expiring in 2017 [Member] Letters of Credit Expiring in 2017 [Member] Litigation Case [Axis] Litigation Case [Axis] Litigation Case [Domain] Litigation Case [Domain] New Mexico Tax Matter New Mexico Tax Matter [Member] Represent information pertaining to New Mexico Tax Matter. Environmental Matters Site Contingency [Line Items] Percentage of share of cost of control Percentage of Share of Cost of Control Represents the percentage of share of the cost of control acquired by the entity. Expected environmental cost Site Contingency, Loss Exposure Not Accrued, Best Estimate Additional percentage share of cost of control Asset Purchase Agreement, Additional Percentage Share of Cost of Control Asset Purchase Agreement, Additional Percentage Share of Cost of Control Site contingency increase in loss exposure not accrued, best estimate Asset Purchase Agreement, Site Contingency, Increase in Loss Exposure Not Accrued, Best Estimate Asset Purchase Agreement, Site Contingency, Increase in Loss Exposure Not Accrued, Best Estimate Clean power plan, optional extension period Clean Power Plan, Optional Extension Period Clean Power Plan, Optional Extension Period Coal severance surtax, penalty, and interest Loss Contingency Coal Severance Surtax Penalty and Interest Represent information pertaining to total amount of coal severance surtax, penalty, and interest related to coal supplied under the coal supply agreement. Share of the assessment Loss Contingency Assessment Share Represent information pertaining to share of the assessment. Partial payment of assessment Loss Contingency, Partial Payment of Assessment Loss Contingency, Partial Payment of Assessment Litigation settlement awarded (against), amount Litigation Settlement, Amount Financial Assurances Financial Assurances [Abstract] Number of letters of credit expiring Number of Letters of Credit Expiring Represents the number of letters of credit expiring. Other Income and Expenses [Abstract] Component of Other Income and Other Expense Nonoperating [Table] Component of Other Income and Other Expense Nonoperating [Table] Provides a description and amount of each detailed component of other nonoperating income and expenses. Component of Other Income and Other Expense Nonoperating [Line Items] Component of Other Income and Other Expense Nonoperating [Line Items] Component of Other Income and Other Expense Nonoperating [Line Items] Other Income and Other Expense Other Income and Other Expense Disclosure [Text Block] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Income Statement [Abstract] OPERATING REVENUES Revenue, Net ELECTRIC OPERATING REVENUES Electric Domestic Regulated Revenue OPERATING EXPENSES Costs and Expenses [Abstract] Fuel and purchased power Cost of Goods Sold, Electric Operations and maintenance Utilities Operating Expense, Maintenance and Operations Depreciation and amortization Cost of Services, Depreciation and Amortization Income taxes Operating Income Tax Expense (Benefit) The sum of the current income tax expense (benefit) and the deferred income tax expense (benefit) pertaining to operating income. Taxes other than income taxes Taxes, Miscellaneous Other expenses Other Cost and Expense, Operating Total Costs and Expenses OPERATING INCOME Operating Income (Loss) OTHER INCOME (DEDUCTIONS) Nonoperating Income (Expense) [Abstract] Income taxes Nonoperating Income Tax Expense (Benefit) The sum of the current income tax expense (benefit) and the deferred income tax expense (benefit) pertaining to non-operating income. Allowance for equity funds used during construction Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity Other income (Note 8) Other Nonoperating Income Other expense (Note 8) Other Nonoperating Expense Total Nonoperating Income (Expense) INTEREST EXPENSE Interest Expense [Abstract] Interest charges Interest Costs Incurred Interest on long-term debt Interest Expense, Long-term Debt Interest on short-term borrowings Interest Expense, Short-term Borrowings Debt discount, premium and expense Debt Related Commitment Fees and Debt Issuance Costs Allowance for borrowed funds used during construction Allowance for Funds Used During Construction, Capitalized Interest Total Interest Expense INCOME BEFORE INCOME TAXES Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest INCOME TAXES Income Tax Expense (Benefit) NET INCOME Less: Net income attributable to noncontrolling interests (Note 5) Net Income (Loss) Attributable to Noncontrolling Interest NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING - BASIC (in shares) WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING - DILUTED (in shares) EARNINGS PER WEIGHTED-AVERAGE COMMON SHARE OUTSTANDING Net income attributable to common shareholders - basic (in dollars per share) Net income attributable to common shareholders - diluted (in dollars per share) Variable Interest Entities [Abstract] Variable Interest Entities [Abstract] Amounts relating to the VIEs included in Condensed Consolidated Balance Sheets Schedule of Variable Interest Entities [Table Text Block] Statement of Cash Flows [Abstract] CASH FLOWS FROM OPERATING ACTIVITIES Net Cash Provided by (Used in) Operating Activities [Abstract] NET INCOME Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization including nuclear fuel Depreciation, Depletion and Amortization Deferred fuel and purchased power Increase (Decrease) in Regulatory Clause Revenue Deferred fuel and purchased power amortization Increase (Decrease) Deferred Fuel and Purchased Power Amortization The amortization of deferred fuel and purchased power costs. Allowance for equity funds used during construction Deferred income taxes Deferred Income Tax Expense (Benefit) Deferred investment tax credit Investment Tax Credit Change in derivative instruments fair value Unrealized Gain (Loss) on Derivatives Changes in current assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Customer and other receivables Increase (Decrease) in Receivables Accrued unbilled revenues Increase (Decrease) in Unbilled Receivables Materials, supplies and fossil fuel Increase (Decrease) in Inventories Income tax receivable Increase (Decrease) in Income Taxes Receivable Other current assets Increase (Decrease) in Prepaid Expense Accounts payable Increase (Decrease) in Accounts Payable Accrued taxes Increase (Decrease) in Accrued Taxes Payable Other current liabilities Increase (Decrease) in Other Accrued Liabilities Change in margin and collateral accounts — assets Increase (Decrease) in Deposit Assets Change in margin and collateral accounts — liabilities Change in Margin and Collateral Accounts Liabilities The aggregate net change during the reporting period in moneys received as security, collateral, or margin deposits. Change in other long-term assets Increase (Decrease) in Other Operating Assets Change in other long-term liabilities Increase (Decrease) in Other Operating Liabilities Net cash flow provided by operating activities Net Cash Provided by (Used in) Operating Activities CASH FLOWS FROM INVESTING ACTIVITIES Net Cash Provided by (Used in) Investing Activities [Abstract] Capital expenditures Payments to Acquire Productive Assets Contributions in aid of construction Proceeds from Contribution in Aid of Construction Allowance for borrowed funds used during construction Allowance for Funds Used During Construction, Investing Activities Proceeds from nuclear decommissioning trust sales Investment in nuclear decommissioning trust Payments to Acquire Investments to be Held in Decommissioning Trust Fund Other Payments for (Proceeds from) Other Investing Activities Net cash flow used for investing activities Net Cash Provided by (Used in) Investing Activities CASH FLOWS FROM FINANCING ACTIVITIES Net Cash Provided by (Used in) Financing Activities [Abstract] Issuance of long-term debt Proceeds from Issuance of Long-term Debt Short-term borrowings and payments — net Proceeds from (Repayments of) Short-term Debt Dividends paid on common stock Payments of Ordinary Dividends, Common Stock Common stock equity issuance - net of purchases Proceeds from (Repurchase of) Equity Other Proceeds from (Payments for) Other Financing Activities Net cash flow provided by financing activities Net Cash Provided by (Used in) Financing Activities NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS Cash and Cash Equivalents, Period Increase (Decrease) CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD Cash and Cash Equivalents, at Carrying Value CASH AND CASH EQUIVALENTS AT END OF PERIOD Supplemental disclosure of cash flow information Supplemental Cash Flow Information [Abstract] Cash paid during the period for: Cash Paid During Period [Abstract] Income taxes, net of refunds Income Taxes Paid, Net Interest, net of amounts capitalized Interest Paid, Net Significant non-cash investing and financing activities: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Accrued capital expenditures Capital Expenditures Incurred but Not yet Paid Fair Value Measurements Fair Value Disclosures [Text Block] AOCI Including Portion Attributable to Noncontrolling Interest AOCI Including Portion Attributable to Noncontrolling Interest [Member] Accumulated Net Investment Gain (Loss) Including Portion Attributable to Noncontrolling Interest Accumulated Net Investment Gain (Loss) Including Portion Attributable to Noncontrolling Interest [Member] Accumulated Defined Benefit Plans Adjustment Including Portion Attributable to Noncontrolling Interest Accumulated Defined Benefit Plans Adjustment Including Portion Attributable to Noncontrolling Interest [Member] AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] OCI (loss) before reclassifications Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Amounts reclassified from accumulated other comprehensive loss Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Total other comprehensive income Loss Contingencies [Table] Loss Contingencies [Table] Loss Contingency Nature [Axis] Loss Contingency Nature [Axis] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Contaminated groundwater wells Contaminated Groundwater Wells [Member] Represents information pertaining to the contaminated groundwater wells. Loss Contingencies [Line Items] Loss Contingencies [Line Items] Costs related to investigation and study under Superfund site Costs Related to Investigation and Study under Superfund Site Costs related to site-wide groundwater remedial investigation and feasibility study work plan because subsidiary has been found to be potentially responsible parties ("PRPs") with liability for cleanup of hazardous substances that contaminates the soil, water or air, under the Comprehensive Environmental Response, Compensation and Liability Act ("Superfund"). Number of defendants against whom Roosevelt Irrigation District (RID) filed lawsuit Loss Contingency, Number of Defendants Capacity of transmission line that tripped out of service (in kV) Power Outage Capacity of Transmission Line that Tripped out of Service Power Outage Capacity of Transmission Line that Tripped out of Service Period, after the transmission line went off-line, over which generation and transmission resources for the Yuma area were lost Power Outage Period Over which Generation and Transmission Resources were Lost Represents the period, after the transmission line went off-line, until the generation and transmission resources were lost in the power outage. Number of customers losing service in Yuma area Power Outage Number of Customers Losing Service Represents the number of customers losing service after the generation and transmission resources were lost in the power outage. Fair value of assets and liabilities that are measured at fair value on a recurring basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments Fair Value Inputs, Assets, Quantitative Information [Table Text Block] Changes in fair value for assets and liabilities that are measured at fair value on a recurring basis using Level 3 inputs Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis Unobservable Input Reconciliation [Table Text Block] Tabular disclosure of the fair value measurement of assets and liabilities using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances. Outstanding gross notional amount of derivatives, which represents both purchases and sales (does not reflect net position) Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block] Gains and losses from derivative instruments in designated cash flow accounting hedges relationships Derivative Instruments, Gain (Loss) [Table Text Block] Gains and losses from derivative instruments not designated as accounting hedges instruments Schedule of Other Derivatives Not Designated as Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block] Schedule of offsetting assets Offsetting Assets [Table Text Block] Schedule of offsetting liabilities Offsetting Liabilities [Table Text Block] Information about derivative instruments that have credit-risk-related contingent features Schedule of Derivative Credit Risk Related Contingent Features [Table Text Block] Tabular disclosure of derivative instruments that have credit-risk-related contingent features. Public Utilities General Disclosures [Table] Public Utilities General Disclosures [Table] Public Utilities, Regulatory Proceeding [Axis] Public Utilities, Regulatory Proceeding [Axis] Public Utilities, Regulatory Proceeding [Domain] Public Utilities, Regulatory Proceeding [Domain] RES Arizona Renewable Energy Standard and Tariff [Member] Represents the RES program which permits a surcharge as part of customer bills to recover approved amounts for use in renewable energy projects. 2014 RES Arizona Renewable Energy Standard and Tariff 2014 [Member] Represents the RES program, which permits a surcharge for 2014 as a part of customer bills to recover approved amounts for use in renewable energy projects. 2015 RES Arizona Renewable Energy Standard and Tariff 2015 [Member] Arizona Renewable Energy Standard and Tariff 2015 [Member] 2016 RES Arizona Renewable Energy Standard and Tariff 2016 [Member] Arizona Renewable Energy Standard and Tariff 2016 [Member] 2015 DSMAC Demand Side Management Adjustor Charge 2015 [Member] Demand Side Management Adjustor Charge 2015 [Member] 2016 DSMAC Demand Side Management Adjustor Charge 2016 [Member] Demand Side Management Adjustor Charge 2016 [Member] Electric energy efficiency standard Electric Energy Efficiency Standard [Member] Electric Energy Efficiency Standard [Member] Power Supply Adjustor (PSA) Power Supply Adjustor [Member] Represents the Power Supply Adjustment Plan which permits a surcharge for variations in retail fuel and purchased power costs. Transmission Rates, Transmission Cost Adjustor and Other Transmission Matters Open Access Transmission Tariff [Member] Represents the formula rate-setting methodology to reflect and recover costs incurred in providing transmission services. Lost Fixed Cost Recovery Mechanism Lost Fixed Cost Recovery Mechanisms [Member] Represents lost fixed cost recovery mechanism. Net Metering Net Metering [Member] Represents information pertaining to the proposed solution to the ACC to fix the cost shift brought by current net metering rules. Public Utility, Program [Axis] Public Utility, Program [Axis] Public Utility, Program [Axis] Public Utility, Program [Domain] Public Utility, Program [Domain] [Domain] for Public Utility, Program [Axis] AZ Sun Program AZ Sun Program [Member] AZ Sun Program [Member] Alternative to AZ Sun Program Alternative to AZ Sun Program [Member] Alternative to AZ Sun Program [Member] Alternative to AZ Sun Program, Phase 1 Alternative to AZ Sun Program, Phase 1 [Member] Alternative to AZ Sun Program, Phase 1 [Member] Alternative to AZ Sun Program Phase 2 Alternative to AZ Sun Program Phase 2 [Member] Alternative to AZ Sun Program Phase 2 [Member] Public Utilities Regulatory, Regulatory Matters [Axis] Public Utilities Regulatory, Regulatory Matters [Axis] Represents information by various regulatory matters. Public Utilities Regulatory, Regulatory Matters [Domain] Public Utilities Regulatory, Regulatory Matters [Domain] Represents various regulatory matters. Filing with the Arizona Corporation Commission Filing with Arizona Corporation Commission [Member] Represents the filing with the Arizona Corporation Commission. Cost Recovery Mechanisms Cost Recovery Mechanisms [Member] Represents the cost recovery mechanisms. FERC United States Federal Energy Regulatory Commission [Member] Represents the Federal Energy Regulatory Commission (FERC). Arizona Secretary of State Arizona Secretary of State [Member] Arizona Secretary of State [Member] Year of Rate Cases [Axis] Year of Rate Cases [Axis] Year for which the rate cases are filed. Year of Cases [Domain] Year of Cases [Domain] Year for which the rate cases are filed. Retail rate case filing Retail Rate Case Filing [Member] Represents the general retail rate case filing. Public Utilities, General Disclosures [Line Items] Public Utilities, General Disclosures [Line Items] Net retail rate increase Public Utilities, Requested Rate Increase (Decrease), Amount Approximate percentage of increase in the average retail customer bill Rate Matter, Approximate Percentage of Increase in Average Retail Customer Bill Approximate percentage of increase in the average retail customer bill due to request for net retail base rate increase. Settlement Agreement Public Utilities, Rate Matters, Approved [Abstract] Net change in base rates Public Utilities, Approved Rate Increase (Decrease), Amount Non-fuel base rate increase Settlement Agreement, Non Fuel Base Rate, Increase Amount of increase in non-fuel base rates as per the terms of the settlement agreement of a regulatory matter. Fuel-related base rate decrease Settlement Agreement Fuel Related Base Rate Decrease Amount of decrease in fuel-related base rates as per the terms of the settlement agreement of a regulatory matter. Current base fuel rate (in dollars per kWh) Rate Matter, Base Fuel Rate Current Represents the current base rate for fuel and purchased power costs. Approved base fuel rate (in dollars per kWh) Settlement Agreement Base Fuel Rate Proposed Represents the base rate for fuel and purchased power costs as per the terms of the settlement agreement of a regulatory matter. Estimated amount of transfer of cost recovery for certain renewable energy projects from the RES surcharge to base rates Settlement Agreement Transfer of Cost Recovery to Base Rates Estimated amount of transfer of cost recovery for certain renewable energy projects from the RES surcharge to base rates as per the terms of the settlement agreement of a regulatory matter. Authorized return on common equity (as a percent) Public Utilities, Approved Return on Equity, Percentage Percentage of debt in capital structure Public Utilities, Approved Debt Capital Structure, Percentage Percentage of common equity in capital structure Public Utilities, Approved Equity Capital Structure, Percentage Deferral of property taxes in 2012, if Arizona property tax rates increase (as a percent) Settlement Agreement Percentage of Deferral of Property Taxes if Arizona Property Tax Rates Increase, Year One Percentage of deferral of property taxes in year one, if Arizona property tax rates increase. Deferral of property taxes in 2013, if Arizona property tax rates increase (as a percent) Settlement Agreement Percentage of Deferral of Property Taxes if Arizona Property Tax Rates Increase, Year Two Percentage of deferral of property taxes in year two, if Arizona property tax rates increase. Deferral of property taxes for 2014 and subsequent years, if Arizona property tax rates increase (as a percent) Settlement Agreement Percentage of Deferral of Property Taxes if Arizona Property Tax Rates Increase, Year Three and Thereafter Percentage of deferral of property taxes for year three and thereafter, if Arizona property tax rates increase. Deferral of property taxes in all years, if Arizona property tax rates decrease (as a percent) Settlement Agreement Percentage of Deferral of Property Taxes if Arizona Property Tax Rates Decrease Percentage of deferral of property taxes in all years, if Arizona property tax rates decrease. Annual cost recovery due to modifications to the Environmental Improvement Surcharge Settlement Agreement Modifications to EIS Cost Recovery Amount of cost recovery due to modifications to the Environmental Improvement Surcharge (EIS) as per the terms of the settlement agreement of a regulatory matter. Elimination of the sharing provision of fuel and purchased power costs Settlement Agreement Current Sharing Provision of Fuel and Purchased Power Costs Elimination Represents the elimination of the current sharing provision of fuel and purchased power costs. Period to process the subsequent rate cases Rate Matter, Process Period The period of time subsequent to the findings of the staff of the regulatory entity in which the parties agreed to process the rate matter in good faith. ACC staff sufficiency findings, general period of time Rate Matter, Findings Period The period of time which the staff of the regulatory entity generally requires prior to issuance of its findings. Plan term Rate Matter, Plan Term The period of time covered by a plan to implement a standard enacted by a regulatory authority. Request to build additional utility scale solar, capacity Public Utilities, Request to Build Additional Utility Scale Solar, Capacity Public Utilities, Request to Build Additional Utility Scale Solar, Capacity Additional capacity from APS-owned non AZ Sun projects, impacted customers Public Utilities, Request to Build Additional Utility Scale Solar, Number of Customers Public Utilities, Request to Build Additional Utility Scale Solar, Number of Customers Amount of proposed budget Rate Matter, Proposed Budget Represents the amount of proposed budget. Amount of approved budget Rate Matter, Approved Budget Represents the amount of approved budget. Number of resource savings projects Rate Matter, Number of Resource Savings Projects Rate Matter, Number of Resource Savings Projects Number of workshops Public Utilities, Cost Effective Energy Efficiency Programs, Number of Workshops Public Utilities, Cost Effective Energy Efficiency Programs, Number of Workshops Change in regulatory asset Deferred Fuel and Purchased Power Regulatory Asset (Liability) [Roll Forward] Beginning balance Deferred Fuel and Purchased Power Regulatory Asset (Liability), Current Deferred Fuel and Purchased Power Regulatory Asset (Liability), Current Deferred fuel and purchased power costs — current period Amounts charged to customers Ending balance PSA rate (in dollars per kWh) PSA Rate 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. PSA rate for prior year (in dollars per kWh) PSA Rate in Prior Years 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. Forward component of increase in PSA (in dollars per kWh) Forward Component of PSA Rate Represents the forward component of increase in PSA. Historical component of increase in PSA (in dollars per kWh) Historical Component of PSA Rate Represents the historical component of increase in PSA. Transition component increase in PSA (in dollars per kWh) Transition Component of PSA Rate Transition Component of PSA Rate Increase in annual wholesale transmission rates Rate Matters, Increase in Cost Recovery The increase in annual wholesale transmission rates as a result of a regulatory action. Fixed costs recoverable per residential power lost (in dollars per kWh) Rate Matter, Fixed Cost Recoverable Per Residential Power Lost Represents fixed costs recovered by the LFCR mechanism per residential kWh lost. Fixed costs recoverable per non-residential power lost (in dollars per kWh) Rate Matter, Fixed Cost Recoverable Per Non Residential Power Lost Represents fixed costs recovered by the LFCR mechanism per non-residential kWh lost. Percentage of retail revenues Rate Matter Cap Percentage of Retail Revenue Represents information pertaining to cap percentage of retail revenues. Amount of adjustment representing prorated sales losses approval Amount of Adjustment Representing Prorated Sales Losses Approved Amount of Adjustment Representing Prorated Sales Losses Approved Amount of adjustment representing prorated sales losses pending approval Amount of Adjustment Representing Prorated Sales Losses Pending Approval Amount of Adjustment Representing Prorated Sales Losses Pending Approval Increase in amount of adjustment representing prorated sales losses Increase in Amount of Adjustment Representing Prorated Sales Losses Increase in Amount of Adjustment Representing Prorated Sales Losses Charge on future customers who install rooftop solar panels (in dollars per kWh) Rate Matter Charge on Future Customers who Install Rooftop Solar Panels Represents the Charge on future customers who install rooftop solar panels under order issued on net metering proposal. Estimated monthly collection due to charge on future customers who install rooftop solar panels Rate Matter Estimated Monthly Collection Due to Charge on Future Customers who Install Rooftop Solar Panels Represents the amount of estimated monthly collection due to charge on future customers who install rooftop solar panels under order issued on net metering proposal. Rate benefits preservation initiative, number of signatures required Rate Benefits Preservation Initiative, Number of Signatures Required Rate Benefits Preservation Initiative, Number of Signatures Required Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Recurring Fair Value, Measurements, Recurring [Member] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Quoted Prices in Active Markets for Identical Assets (Level 1) Fair Value, Inputs, Level 1 [Member] Significant Other Observable Inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Significant Unobservable Inputs (a) (Level 3) Fair Value, Inputs, Level 3 [Member] Eligible Item or Group for Fair Value Option [Axis] Financial Instrument [Axis] Fair Value, Option, Eligible Item or Group [Domain] Financial Instruments [Domain] US commingled equity funds U.S. Commingled Funds [Member] A professionally managed investment fund of equity securities established by an investment company regulated by the Securities Exchange Commission or a bank regulated by the Office of the Comptroller of the Currency. The investment fund limits it's investments to equity securities located in the United States. Cash and cash equivalent funds Cash and Cash Equivalents [Member] U.S. Treasury US Treasury Securities [Member] Corporate debt Corporate Debt Securities [Member] Mortgage-backed securities Collateralized Mortgage Backed Securities [Member] Municipality bonds US States and Political Subdivisions Debt Securities [Member] Other Other Debt Obligations [Member] Fair value of assets and liabilities that are measured at fair value on a recurring basis Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Assets Assets, Fair Value Disclosure [Abstract] Gross derivative assets Derivative instruments, other Derivative Asset, Fair Value, Gross Liability Derivative assets Decommissioning fund investments, gross fair value Decommissioning Fund Investments, Gross Fair Value Decommissioning Fund Investments, Gross Fair Value Nuclear decommissioning trust, other Decommissioning Fund Investments, Fair Value Net Pending Securities Sales and Purchases Decommissioning Fund Investments, Fair Value Net Pending Securities Sales and Purchases Nuclear decommissioning trust Gross assets, fair value disclosure Gross Assets, Fair Value Disclosure Gross Assets, Fair Value Disclosure Total, other Derivative Asset, Fair Value, Gross Liability and Net Pending Securities Sales and Purchases Derivative Asset, Fair Value, Gross Liability and Net Pending Securities Sales and Purchases Total assets Liabilities Liabilities, Fair Value Disclosure [Abstract] Gross derivative liability Total, other Derivative Liability, Fair Value, Gross Asset Derivative liability Long-Term Debt and Liquidity Matters Long-term Debt [Text Block] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Other Benefits Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Other Postretirement Benefit Plan Remeasurement Defined Benefit Plan, Plan Amendment [Abstract] Other postretirement plan benefit remeasurement, amount seeking approval to move to separate account to Pay Union employee medical costs Defined Benefit Plan, Amount Seeking Approval to Move to Separate Account to Pay Union Employee Medical Costs Defined Benefit Plan, Amount Seeking Approval to Move to Separate Account to Pay Union Employee Medical Costs Regulatory Assets Regulatory Assets and Liabilities Disclosure [Abstract] Regulatory asset amortization period Regulatory Asset, Amortization Period Amortization of regulatory asset Amortization of Regulatory Asset Contributions Defined Benefit Plan Employer Contributions [Abstract] Voluntary employer contributions to pension plan Defined Benefit Plan, Contributions by Employer Minimum employer contributions for the next three years Defined Benefit Plans Estimated Minimum Future Employer Contributions, Next Three Fiscal Years Defined Benefit Plans Estimated Minimum Future Employer Contributions, Next Three Fiscal Years Maximum employer contributions for the next two years (up to) Defined Benefit Plans Estimated Maximum Future Employer Contributions, Next Three Fiscal Years Defined Benefit Plans Estimated Maximum Future Employer Contributions, Next Three Fiscal Years 2016 (up to) Defined Benefit Plan Estimated Future Employer Contributions in Year Two Defined Benefit Plan Estimated Future Employer Contributions in Year Two 2017 (up to) Defined Benefit Plans Estimated Future Employer Contributions in Year Three Defined Benefit Plans Estimated Future Employer Contributions in Year Three 2015 Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Variable Interest Entities [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Consolidation of VIEs Variable Interest Entity, Primary Beneficiary [Member] Sale Leaseback Transaction Period [Axis] Sale Leaseback Transaction Period [Axis] Represents information pertinent to sale and leaseback period. Sale Leaseback Transaction Period [Domain] Sale Leaseback Transaction Period [Domain] Represents details pertaining to sale and leaseback period. Through 2023 Sale Leaseback Transaction Period Through 2023 [Member] Represents information pertaining to sale and leaseback period through 2023. Through 2033 Sale Leaseback Transaction Period Through 2033 [Member] Represents information pertaining to sale and leaseback period through 2033. Period 2016 through 2023 Sale Leaseback Transaction Period 2016 Through 2023 [Member] Represents information pertaining to sale and leaseback period 2016 through 2023. Period 2024 through 2033 Sale Leaseback Transaction Period 2024 Through 2033 [Member] Represents information pertaining to sale and leaseback period 2024 through 2033. Palo Verde Sale Leaseback Variable Interest Entities Variable Interest Entity [Line Items] Number of VIE lessor trusts Number of VIE Lessor Trusts Number of VIE lessor trusts with whom agreements have been made to sell and lease back interests in certain nuclear generating assets and related common facilities. Number of leases under which assets are retained Sale Leaseback Transaction Number of Leases under which Assets Retained Through Specified Period Represents the number of leases under which assets are retained through a specified period. Annual lease payments Sale Leaseback Transaction, Annual Rental Payments Lease period (up to) Sale Leaseback Transaction Lease Period Represents the period of lease entered into in connection with the transaction involving the sale of property to another party and the lease of the property back to the seller. Increase in net income due to consolidation of Palo Verde Sale Leaseback Trusts Initial loss exposure to the VIE's noncontrolling equity participants during lease extension period Variable Interest Entity, Entity Initial Loss Exposure to Noncontrolling Interests During Lease Extension Period, Amount Variable Interest Entity, Entity Initial Loss Exposure to Noncontrolling Interests During Lease Extension Period, Amount Maximum loss exposure to the VIE's noncontrolling equity participants during lease extension period Variable Interest Entity, Entity Maximum Loss Exposure to Noncontrolling Interests During Lease Extension Period, Amount Variable Interest Entity, Entity Maximum Loss Exposure to Noncontrolling Interests During Lease Extension Period, Amount Percentage of unrealized gains and losses on certain derivatives deferred for future rate treatment Percentage of Unrealized Gains and Losses on Certain Derivatives Deferred for Future Rate Treatment Percentage of unrealized gains and losses on certain derivatives deferred for future rate treatment pursuant to the PSA mechanism that would otherwise be recognized in income. Estimated net gain (loss) before income taxes to be reclassified from accumulated other comprehensive income Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months Gross recognized derivatives Concentration of credit risk, number of counterparties Derivative Instrument Concentration of Risk Counterparties The number of counterparties involved in risk management contracts for which the concentration of risk is disclosed. Concentration of risk with two counterparties, as a percentage of risk management assets Concentration Risk, Percentage Risk management activities-derivative instruments: Commodity Contracts Additional collateral to counterparties for energy related non-derivative instrument contracts Non Derivative Credit Risk Contract Additional Collateral Aggregate Fair Value The aggregate fair value of additional assets that would be required to be posted as collateral for non-derivative instruments with credit-risk related contingent features if the credit-risk-related contingent features were triggered at the end of the reporting period. Schedule of Regulatory Liabilities [Table] Schedule of Regulatory Liabilities [Table] Regulatory Liability [Axis] Regulatory Liability [Axis] Regulatory Liability [Domain] Regulatory Liability [Domain] Asset retirement obligations Asset Retirement Obligation Costs [Member] Removal costs Removal Costs [Member] Other postretirement benefits Postretirement Benefit Costs [Member] Income taxes — deferred investment tax credit Investment Tax Credit Carryforward [Member] Income taxes — change in rates Deferred Income Tax Charge [Member] Spent nuclear fuel Spent Nuclear Fuel [Member] Liability associated with spent nuclear fuel. Renewable energy standard (b) Renewable Energy Program [Member] Demand side management (b) Demand Side Management [Member] Demand Side Management [Member] Sundance maintenance Sundance Maintenance [Member] Sundance Maintenance [Member] Deferred fuel and purchased power (b) (c) Deferred Fuel and Purchased Power [Member] Deferred Fuel and Purchased Power [Member] Deferred gains on utility property Deferred Gains on Utility Property [Member] Deferred Gains on Utility Property [Member] Four Corners coal reclamation Four Corners Coal Reclamation [Member] Four Corners Coal Reclamation [Member] Other Other Regulatory Liabilities [Member] Miscellaneous regulatory liabilities which are individually insignificant. Detail of regulatory liabilities Regulatory Liabilities [Line Items] Regulatory liabilities, current Regulatory Liability, Including Deferred Fuel and Purchased Power Regulatory Liability Current The amount for the individual regulatory current liability including deferred fuel and purchased power as itemized in a table of regulatory current liabilities as of the end of the period. Regulatory liabilities, non-current Regulatory Liability, Noncurrent Consolidation and Nature of Operations Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Statement of Financial Position [Abstract] ASSETS Assets [Abstract] CURRENT ASSETS Assets, Current [Abstract] Cash and cash equivalents Customer and other receivables Accounts Receivable, Gross, Current Accrued unbilled revenues Costs in Excess of Billings, Current Allowance for doubtful accounts Allowance for Doubtful Accounts Receivable, Current Materials and supplies (at average cost) Other Inventory, Supplies, Gross Fossil fuel (at average cost) Energy Related Inventory, Other Fossil Fuel Income tax receivable Income Taxes Receivable, Current Assets from risk management activities (Note 6) Derivative Instruments and Hedges, Assets Regulatory assets (Note 3) Regulatory Assets, Current Other current assets Other Assets, Current Total current assets Assets, Current INVESTMENTS AND OTHER ASSETS Investments and Other Assets [Abstract] Assets from risk management activities (Note 6) Derivative Instruments and Hedges, Noncurrent Nuclear decommissioning trust (Note 11) Other assets Other Assets, Noncurrent Total investments and other assets Total Investments and Other Assets Sum of the carrying amounts as of the balance sheet date of all investments and other assets that are expected to be realized in cash, sold, or consumed at a future date that exceeds one year from the balance sheet date. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. PROPERTY, PLANT AND EQUIPMENT Property, Plant and Equipment, Net [Abstract] Plant in service and held for future use Property, Plant and Equipment, Gross Accumulated depreciation and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Net Property, Plant and Equipment, Net Construction work in progress Construction in Progress, Gross Palo Verde sale leaseback, net of accumulated depreciation (Note 5) Variable Interest Entity, Consolidated, Carrying Amount, Assets Intangible assets, net of accumulated amortization Intangible Assets, Net (Excluding Goodwill) Nuclear fuel, net of accumulated amortization Nuclear Fuel, Net of Amortization Total property, plant and equipment Public Utilities, Property, Plant and Equipment, Net DEFERRED DEBITS Deferred Costs [Abstract] Regulatory assets (Note 3) Regulatory Assets, Noncurrent Assets for other postretirement benefits (Note 4) Defined Benefit Plan, Assets for Plan Benefits, Noncurrent Other Other Deferred Costs, Net Total deferred debits Total Deferred Debits Sum of the carrying amounts as of the balance sheet date of all regulatory assets and other deferred debits that are expected to be recovered through revenue sources (or the normal operating cycle, if longer). TOTAL ASSETS Assets LIABILITIES AND EQUITY Liabilities and Equity [Abstract] CURRENT LIABILITIES Liabilities, Current [Abstract] Accounts payable Accounts Payable, Current Accrued taxes Taxes Payable, Current Accrued interest Interest Payable, Current Common dividends payable Dividends Payable, Current Short-term borrowings (Note 2) Short-term Debt Current maturities of long-term debt (Note 2) Other Long-term Debt, Current Customer deposits Customer Deposits, Current Liabilities from risk management activities (Note 6) Derivative Instruments and Hedges, Liabilities Liabilities for asset retirements Deferred Fuel and Purchased Power Regulatory Liability, Current Deferred Fuel and Purchased Power Regulatory Liability, Current Deferred fuel and purchased power regulatory liability (Note 3) Asset Retirement Obligation, Current Other regulatory liabilities (Note 3) Regulatory Liability, Current Other current liabilities Other Liabilities, Current Total current liabilities Liabilities, Current LONG-TERM DEBT LESS CURRENT MATURITIES (Note 2) Long-term Debt, Excluding Current Maturities DEFERRED CREDITS AND OTHER Deferred Credits and Other Liabilities [Abstract] Deferred income taxes Deferred Tax Liabilities, Net, Noncurrent Regulatory liabilities (Note 3) Liabilities for asset retirements Asset Retirement Obligations, Noncurrent Liabilities for pension benefits (Note 4) Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent Liabilities from risk management activities (Note 6) Derivative Liability, Noncurrent Customer advances Customer Advances for Construction Coal mine reclamation Mine Reclamation and Closing Liability, Noncurrent Deferred investment tax credit Accumulated Deferred Investment Tax Credit Unrecognized tax benefits Liability for Uncertainty in Income Taxes, Noncurrent Other Other Liabilities, Noncurrent Total deferred credits and other Deferred Credits and Other Liabilities COMMITMENTS AND CONTINGENCIES (SEE NOTES) Commitments and Contingencies EQUITY Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Common stock, no par value; authorized 150,000,000 shares, 111,147,524 and 111,095,402 issued at respective dates Common Stock, Value, Issued Treasury stock at cost; 7,936 and 115,030 shares at respective dates Treasury Stock, Value Total common stock Common Stock, Value, Outstanding Additional paid-in capital Additional Paid in Capital, Common Stock Retained earnings Retained Earnings (Accumulated Deficit) Accumulated other comprehensive loss: Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Pension and other postretirement benefits Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax Derivative instruments Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax Total accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Total shareholders’ equity Noncontrolling interests (Note 5) Stockholders' Equity Attributable to Noncontrolling Interest Total equity Long-term debt less current maturities (Note 2) Long-term Debt and Capital Lease Obligations Total capitalization Equity and Long Term Debt Less Current Maturities and Leaseback The sum of total shareholder equity and long-term debt, excluding current maturities of long-term debt and leaseback. TOTAL LIABILITIES AND EQUITY Liabilities and Equity Schedule of changes in the deferred fuel and purchased power regulatory asset Schedule of Deferred Fuel and Purchased Power Regulatory Asset (Liability) [Table Text Block] Tabular disclosure of the changes in the deferred fuel and purchased power regulatory asset (liability) of regulated entities. Schedule of regulatory assets Schedule of Regulatory Assets [Table Text Block] Schedule of regulatory liabilities Schedule of Regulatory Liabilities [Table Text Block] Palo Verde Sale Leaseback Variable Interest Entities Variable Interest Entity Disclosure [Text Block] Schedule of estimated fair value of long-term debt, including current maturities Fair Value, by Balance Sheet Grouping [Table Text Block] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair value of derivative instruments with credit risk and credit-related contingent features Derivatives, Fair Value [Line Items] Credit Risk and Credit-Related Contingent Features Derivative, Credit Risk Related Contingent Features [Abstract] Aggregate fair value of derivative instruments in a net liability position Derivative, Net Liability Position, Aggregate Fair Value Cash collateral posted Collateral Already Posted, Aggregate Fair Value Additional cash collateral in the event credit-risk-related contingent features were fully triggered Additional Collateral, Aggregate Fair Value Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] Net derivative balance at beginning of period Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs Included in OCI Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Other Comprehensive Income (Loss) Deferred as a regulatory asset or liability Fair Value Measurement with Unobservable Inputs Reconciliation Recurring Basis, Derivative Gain (Loss) Deferred as Regulatory Asset or Liability This element represents the total gains or losses for the period (realized and unrealized), arising from assets and liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3), which have been deferred as a regulatory asset or liability. Settlements Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Settlements Transfers into Level 3 from Level 2 Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers into Level 3 Transfers from Level 3 into Level 2 Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers out of Level 3 Net derivative balance at end of period Net unrealized gains included in earnings related to instruments still held at end of period Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Change in Unrealized Gain (Loss) Common stock, par value (in dollars per share) Common Stock, No Par Value Common stock, authorized shares Common Stock, Shares Authorized Common stock, issued shares Treasury stock at cost, shares Treasury Stock, Shares Retirement Plans and Other Postretirement Benefits Pension and Other Postretirement Benefits Disclosure [Text Block] Schedule of Regulatory Assets [Table] Schedule of Regulatory Assets [Table] Pension Pension [Member] Pension [Member] Income taxes — allowance for funds used during construction (AFUDC) equity Deferred fuel and purchased power — mark-to-market (Note 6) Deferred Fuel and Purchased Power MTM Costs [Member] Fuel and purchased power MTM costs incurred that would otherwise be charged to expense. These costs are included in allowable costs for rate making purposes and future revenue will be provided to permit recovery of such incurred costs. Income taxes — investment tax credit basis adjustment Lost fixed cost recovery (b) Lost Fixed Cost Recovery [Member] Represents the regulatory asset under lost fixed recovery mechanisms. Palo Verde VIEs (Note 5) Deferred compensation Deferred Compensation [Member] Represents the regulatory asset under deferred compensation arrangements. Deferred property taxes Deferred Property Taxes [Member] Represents information pertaining to deferred property taxes. Loss on reacquired debt Loss on Reacquired Debt [Member] Tax expense of Medicare subsidy Tax Expense of Medicare Subsidy [Member] Represents the tax expense of Medicare subsidy. Transmission vegetation management Transmission Vegetation Management [Member] Anticipated costs associated with transmission vegetation management to maintain the reliability of overhead transmission lines by minimizing vegetation-caused outages. Mead-Phoenix transmission line CIAC Mead-Phoenix transmission line CIAC [Member] Mead-Phoenix transmission line CIAC [Member] Transmission cost adjustor (b) Transmission Cost Adjustor [Member] Transmission Cost Adjustor [Member] Coal reclamation Coal Reclamation [Member] Reclamation liability that is associated with a legal obligation for the reclamation of coal properties. Other Other Regulatory Assets (Liabilities) [Member] Detail of regulatory assets Regulatory Assets [Line Items] Regulatory assets, current Regulatory Asset Including Deferred Fuel and Purchased Power Regulatory Asset Current 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. Regulatory assets, non-current Regulatory Matters Regulatory Matters [Text Block] This element represents Regulatory Matters. Amounts relating to the VIEs included in Condensed Consolidated Balance Sheets Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract] Palo Verde sale leaseback property plant and equipment, net of accumulated depreciation Equity — Noncontrolling interests Schedule of Commitments and Contingencies [Table] Schedule of Commitments and Contingencies [Table] Discloses the specific components of significant arrangements in which the entity has agreed to expend funds. Breach of Contract for Disposal of Spent Nuclear Fuel and/or High Level Radioactive Waste Arizona Public Service Company and Palo Verde Owners vs. United States Department of Energy - Spent Nuclear Fuel and Waste Disposal [Member] Arizona Public Service Company and Palo Verde Owners vs. United States Department of Energy - Spent Nuclear Fuel and Waste Disposal [Member] Commitments and Contingencies Commitments and Contingencies [Line Items] Litigation settlement amount Number of claims submitted Gain Contingency, New Claims Filed, Number Gain Contingency, New Claims Filed, Number Number of settlement agreement time periods Gain Contingency, Number of Settlement Agreement Time Periods Gain Contingency, Number of Settlement Agreement Time Periods Proceeds from legal settlements Proceeds from Legal Settlements Maximum insurance against public liability per occurrence for a nuclear incident (up to) Maximum Insurance Coverage Per Incident Represents the maximum insurance amount against public liability per occurrence for a nuclear incident. Maximum available nuclear liability insurance (up to) Maximum Available Nuclear Liability Insurance Represents the maximum available nuclear liability insurance which is provided by commercial insurance carriers, maintained by Palo Verde as required by the Price Anderson Nuclear Industries Indemnity Act. Remaining nuclear liability insurance through mandatory industry wide retrospective assessment program Remaining Nuclear Liability Insurance Through Mandatory Industry Wide Retrospective Assessment Program Represents the remaining nuclear liability insurance that is provided through mandatory industry wide retrospective assessment program. Maximum retrospective premium assessment per reactor for each nuclear liability incident Maximum Assessment Per Reactor for Each Nuclear Incident Represents the maximum assessment per reactor under the program for each nuclear incident. Annual limit per incident with respect to maximum retrospective premium assessment Annual Limit Per Incident with Respect to Maximum Assessment Represents the annual limit per incident with respect to the maximum assessment per reactor under the program for each nuclear incident, to be periodically adjusted for inflation. Maximum potential retrospective assessment per incident of APS Maximum Potential Retrospective Assessment Per Incident Represents the maximum potential retrospective assessment per incident based on the interest of APS in the three Palo Verde units. Annual payment limitation with respect to maximum potential retrospective premium assessment Annual Payment Limitation with Respect to Maximum Potential Retrospective Assessment Represents the annual payment limitation with respect to maximum potential retrospective assessment. Amount of "all risk" (including nuclear hazards) insurance for property damage to, and decontamination of, property at Palo Verde All Risk Insurance for Property Damage and Decontamination at Palo Verde Represents the "all risk" (including nuclear hazards) insurance for property damage to, and decontamination of, property at Palo Verde of which a substantial portion must first be applied to stabilization and decontamination. Maximum amount that APS could incur under the current NEIL policies for each retrospective assessment Maximum Amount that Could be Incurred under Retrospective Assessment of NEIL Policies Maximum Amount that Could be Incurred under Retrospective Assessment of NEIL Policies Collateral assurance provided based on rating triggers Collateral Assurance Based on Rating Triggers Represents the collateral assurance provided that depends upon rating triggers such as a rating downgrade to non-investment grade under NEIL policies. Period to provide collateral assurance based on rating triggers Period to Provide Collateral Assurance Based on Rating Triggers Represents the period to provide collateral assurance based on rating triggers such as a rating downgrade to non-investment grade under NEIL policies (in days). Detail of other income and other expense Schedule of Other Nonoperating Income (Expense) [Table Text Block] Earnings Per Share Earnings Per Share [Text Block] OTHER COMPREHENSIVE INCOME, NET OF TAX Other Comprehensive Income (Loss), Net of Tax [Abstract] Derivative instruments: Derivative Instruments and Hedges, Assets [Abstract] Net unrealized gain (loss), net of tax benefit (expense) Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax Reclassification of net realized loss, net of tax benefit Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax Pension and other postretirement benefits activity, net of tax benefit (expense) Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax COMPREHENSIVE INCOME Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Less: Comprehensive income attributable to noncontrolling interests COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS Comprehensive Income (Loss), Net of Tax, Attributable to Parent Other income: Other Income, Nonoperating [Abstract] Interest income Investment Income, Interest Gain on disposition of property Gain on Disposition of Property Plant Equipment Gain on Disposition of Property Plant Equipment Miscellaneous Miscellaneous Other Nonoperating Income Amount of miscellaneous other nonoperating income resulting from ancillary business-related activities (that is, excluding major activities considered as a part of the normal operations of the business). Total other income Other expense: Other Expense, Nonoperating [Abstract] Non-operating costs Nonoperating Costs Amount of nonoperating costs resulting from the ancillary business-related activities (that is, excluding major activities considered as a part of the normal operations of the business) recognized during the period. Investment losses — net Loss on Sale of Investments Loss on disposition of property Loss on Disposition of Property Plant Equipment Loss on Disposition of Property Plant Equipment Miscellaneous Miscellaneous Other Nonoperating Expense Amount of miscellaneous other nonoperating expenses resulting from ancillary business-related activities (that is, excluding major activities considered as a part of the normal operations of the business). Total other expense Changes in Accumulated Other Comprehensive Loss Comprehensive Income (Loss) Note [Text Block]