Asset Retirement Obligations (Details) - ARIZONA PUBLIC SERVICE COMPANY - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Asset Retirement Obligations
Newly incurred or acquired obligations	$ 0	$ 17,864
ARO, decrease		1,000
Change in asset retirement obligations
Asset retirement obligations at the beginning of year	726,545	679,529
Changes attributable to:
Accretion expense	39,726	36,876
Settlements	(12,591)	(9,726)
Estimated cash flow revisions	(96,462)	2,002
Newly incurred or acquired obligations	0	17,864
Asset retirement obligations at the end of year	657,218	726,545
Palo Verde Nuclear Generating Station
Asset Retirement Obligations
ARO, decrease	89,000
Increase in regulatory asset	80,000
Decrease in regulatory liability	9,000
Solar Panels
Asset Retirement Obligations
Newly incurred or acquired obligations		14,000
Changes attributable to:
Newly incurred or acquired obligations		14,000
4CA
Asset Retirement Obligations
ARO, decrease		9,000
Navajo Generating Station
Asset Retirement Obligations
ARO, decrease	$ 8,000
Consumer Solar Panels
Asset Retirement Obligations
Newly incurred or acquired obligations		7,000
Changes attributable to:
Newly incurred or acquired obligations		$ 7,000

Asset Retirement Obligation, Increase in Regulatory Asset

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Asset Retirement Obligation, Liabilities Incurred, Decrease in Regulatory Liability

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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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Amount of asset retirement obligations incurred during the period.

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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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