Leases - Additional information (Details) $ in Millions	Jun. 30, 2020 USD ($) Lease	Jun. 01, 2020 Lease
Leases [Abstract]
Number of lease agreements, lease and sell back	3
Number of lease agreements		2
Lease not yet commenced \| $	$ 258

Lease Not yet Commenced, Liability, Lease and Nonlease Payments

No definition available.

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