Leases - Narrative (Details) $ in Millions	Sep. 30, 2021 USD ($) lease
Leases [Abstract]
Number of lease agreements, lease and sell back \| lease	3
Lease not yet commenced \| $	$ 392

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