| **Revenue - Sources of Revenue (Details) - USD ($) $ in Thousands** | 12 Months Ended |
|---------------------------------------------------------------------|-----------------|
||
| **Disaggregation of Revenue [Line Items]**                          |            |   |
| Total Operating Revenues                                            | $ 3,471,209     | $ 3,691,247 |
| Retail Electric Service | Retail residential                        |            |   |
| **Disaggregation of Revenue [Line Items]**                          |            |   |
| Total Operating Revenues                                            | 1,761,122       | 1,867,370 |
| Retail Electric Service | Retail non-residential                    |            |   |
| **Disaggregation of Revenue [Line Items]**                          |            |   |
| Total Operating Revenues                                            | 1,509,514       | 1,628,891 |
| Retail Electric Service | Wholesale                                 |            |   |
| **Disaggregation of Revenue [Line Items]**                          |            |   |
| Total Operating Revenues                                            | 121,805         | 109,198 |
| Transmission Services for Others                                    |            |   |
| **Disaggregation of Revenue [Line Items]**                          |            |   |
| Total Operating Revenues                                            | 62,460          | 60,261 |
| Other Sources                                                       |            |   |
| **Disaggregation of Revenue [Line Items]**                          |            |   |
| Total Operating Revenues                                            | $ 16,308        | $ 25,527 |

| X                                                                                                                                                                                                                                                                                                                                                                                                                        |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
+ References
No definition available.
+ Details**Name:**us-gaap_DisaggregationOfRevenueLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.
+ References
Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045
+ Details**Name:**us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                          |
|--------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**srt_ProductOrServiceAxis=pnw_ElectricServiceMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                          |
|--------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**srt_MajorCustomersAxis=pnw_RetailResidentialMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                             |
|-----------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**srt_MajorCustomersAxis=pnw_RetailNonResidentialMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                  |
|------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**srt_MajorCustomersAxis=pnw_WholesaleMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                               |
|-------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**srt_ProductOrServiceAxis=pnw_TransmissionServicesMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                        |
|------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**srt_ProductOrServiceAxis=pnw_OtherServicesMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |