No definition available.

Name:	pnw_DebtProvisionsAbstract
Namespace Prefix:	pnw_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the maximum borrowings available for the commercial paper program under the terms of line of credit facility.

+ References

No definition available.

+ Details

Name:	pnw_LineOfCreditFacilityCommercialPaperProgramMaximumBorrowingCapacity
Namespace Prefix:	pnw_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the number of line of credit facilities.

+ References

No definition available.

+ Details

Name:	pnw_LineOfCreditFacilityNumberOfAgreements
Namespace Prefix:	pnw_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Line of Credit Facility, Additional Capacity Increase Available

+ References

No definition available.

+ Details

Name:	pnw_LineofCreditFacilityAdditionalCapacityIncreaseAvailable
Namespace Prefix:	pnw_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the percentage of capitalization which is used to calculate the short-term debt authorization pursuant to an order from a regulatory authority.

+ References

No definition available.

+ Details

Name:	pnw_PublicUtilityOrderShortTermDebtAuthorizationAsPercentageOfCapitalization
Namespace Prefix:	pnw_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the fixed amount required to be used for purchases of natural gas and power which is used to calculate the short-term debt authorization pursuant to an order from a regulatory authority.

+ References

No definition available.

+ Details

Name:	pnw_PublicUtilityOrderShortTermDebtAuthorizationFixedAmount
Namespace Prefix:	pnw_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(13)(2))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(19)(a)(3))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_CommercialPaper
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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

- Details

Name:	dei_LegalEntityAxis=pnw_ArizonaPublicServiceCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RegulatoryAgencyAxis=pnw_ArizonaCorporationCommissionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=pnw_TermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidatedEntitiesAxis=srt_ParentCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pnw_RevolvingCreditFacilityMaturingJuly2023Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pnw_RevolvingCreditFacilityMaturingJune2022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pnw_RevolvingCreditFacilityMaturingin2022and2023Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_LetterOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_CommercialPaperMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Lines of Credit and Short-Term Borrowings - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020 USD ($) Facility	Dec. 23, 2020 USD ($)	Dec. 17, 2020 USD ($)	May 05, 2020 USD ($)	May 04, 2020 USD ($)	Dec. 31, 2019 USD ($)
ARIZONA PUBLIC SERVICE COMPANY \| ACC
Debt Provisions
Percentage of APS's capitalization used in calculation of short-term debt authorization			7.00%
Required amount to be used in purchases of natural gas and power which is used in calculation of short-term debt authorization			$ 500,000,000
Term loan
Lines of Credit and Short-Term Borrowings
Notes issued		$ 150,000,000
Term loan \| Pinnacle West
Lines of Credit and Short-Term Borrowings
Maximum borrowing capacity on credit facility upon satisfaction of certain conditions and consent of lenders					$ 50,000,000
Notes issued				$ 31,000,000
Long-term line of credit	$ 19,000,000
Revolving credit facility
Lines of Credit and Short-Term Borrowings
Long-term line of credit	169,000,000					$ 114,675,000
Amount committed	1,231,000,000					1,250,000,000
Revolving credit facility \| Pinnacle West
Lines of Credit and Short-Term Borrowings
Long-term line of credit	169,000,000					114,675,000
Amount committed	231,000,000					250,000,000
Revolving credit facility \| Pinnacle West \| Revolving credit facility maturing July 2023
Lines of Credit and Short-Term Borrowings
Maximum borrowing capacity on credit facility upon satisfaction of certain conditions and consent of lenders	300,000,000
Long-term line of credit	0
Amount committed	200,000,000
Revolving credit facility \| ARIZONA PUBLIC SERVICE COMPANY
Lines of Credit and Short-Term Borrowings
Long-term line of credit	0					0
Amount committed	1,000,000,000					$ 1,000,000,000
Revolving credit facility \| ARIZONA PUBLIC SERVICE COMPANY \| Revolving credit facility maturing June 2022
Lines of Credit and Short-Term Borrowings
Amount committed	500,000,000
Revolving credit facility \| ARIZONA PUBLIC SERVICE COMPANY \| Revolving credit facility maturing July 2023
Lines of Credit and Short-Term Borrowings
Amount committed	500,000,000
Revolving credit facility \| ARIZONA PUBLIC SERVICE COMPANY \| Revolving Credit Facility Maturing in 2022 and 2023
Lines of Credit and Short-Term Borrowings
Maximum borrowing capacity on credit facility upon satisfaction of certain conditions and consent of lenders	1,400,000,000
Amount committed	$ 1,000,000,000
Number of credit facilities \| Facility	2
Additional capacity increase available	$ 700,000,000
Letter of credit \| Pinnacle West \| Revolving credit facility maturing July 2023
Lines of Credit and Short-Term Borrowings
Outstanding letters of credit	0
Letter of credit \| ARIZONA PUBLIC SERVICE COMPANY
Lines of Credit and Short-Term Borrowings
Outstanding letters of credit	5,200,000
Letter of credit \| ARIZONA PUBLIC SERVICE COMPANY \| Revolving Credit Facility Maturing in 2022 and 2023
Lines of Credit and Short-Term Borrowings
Outstanding letters of credit	0
Commercial paper \| Pinnacle West \| Revolving credit facility maturing July 2023
Lines of Credit and Short-Term Borrowings
Commercial paper	150,000,000
Commercial paper \| ARIZONA PUBLIC SERVICE COMPANY
Lines of Credit and Short-Term Borrowings
Maximum commercial paper support available under credit facility	500,000,000
Commercial paper \| ARIZONA PUBLIC SERVICE COMPANY \| Revolving Credit Facility Maturing in 2022 and 2023
Lines of Credit and Short-Term Borrowings
Commercial paper	$ 0
LIBOR \| Term loan \| Pinnacle West
Lines of Credit and Short-Term Borrowings
Debt instrument, basis spread on variable rate	1.40%