Asset Retirement Obligations (Details) - Arizona Public Service Company - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Change in asset retirement obligations
Asset retirement obligations at the beginning of year	$ 705,083	$ 657,218
Changes attributable to:
Accretion expense	38,437	38,652
Settlements	(4,111)	(9,710)
Estimated cash flow revisions	27,973	18,923
Asset retirement obligations at the end of year	767,382	705,083
Cholla
Asset Retirement Obligations
Increase in asset retirement obligation	$ 28,000
Navajo Generating Station
Asset Retirement Obligations
Increase in asset retirement obligation		6,000
Four Corners Units 4 and 5
Asset Retirement Obligations
Increase in asset retirement obligation		$ 13,000

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The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 50
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-SubTopic 20
-Section 45
-Paragraph 1
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Amount of asset retirement obligations settled, or otherwise disposed of, during the period. This may include asset retirement obligations transferred to third parties associated with the sale of a long-lived asset.

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Amount of increase (decrease) in asset retirement obligations.

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Amount of increase (decrease) in the asset retirement obligation from changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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