Asset Retirement Obligations (Details) (USD $)	1 Months Ended	3 Months Ended
Apr. 30, 2011 y	Mar. 31, 2011
Asset Retirement Obligations
Change in regulatory liabilities		$ 53,000,000
ARIZONA PUBLIC SERVICE COMPANY
Asset Retirement Obligations
Period of license extension approved by the NRC (in years)	20
Decrease to the liability for asset retirements		(90,000,000)
Decrease to electric plant in service		(78,000,000)
Change in regulatory liabilities		$ 12,000,000

The increase (decrease) during the reporting period in regulated liabilities. Regulated liabilities are created when regulatory agency permits an entity to defer revenues to the balance sheet.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 28

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

Name:	us-gaap_IncreaseDecreaseInRegulatoryLiabilities
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration