Costs related to site-wide groundwater remedial investigation and feasibility study work plan because subsidiary has been found to be potentially responsible parties ("PRPs") with liability for cleanup of hazardous substances that contaminates the soil, water or air, under the Comprehensive Environmental Response, Compensation and Liability Act ("Superfund").

No definition available.

Commitments and Contingencies (Details 2) (USD $)	6 Months Ended	1 Months Ended
Commitments and Contingencies (Details 2) (USD $)	Jun. 30, 2012	Jan. 31, 2012 Lawsuit item	Sep. 30, 2011 Lawsuit item	Feb. 29, 2008 Climate Change Lawsuit item	Sep. 30, 2011 ARIZONA PUBLIC SERVICE COMPANY item	Jun. 30, 2012 ARIZONA PUBLIC SERVICE COMPANY	Sep. 08, 2011 ARIZONA PUBLIC SERVICE COMPANY	Jun. 30, 2012 Fuel and purchased power commitments	Jun. 30, 2012 Renewable energy credits
Contractual Obligations
Contractual obligations increase	$ 300,000,000
2012								300,000,000	100,000,000
2013								500,000,000
2014								600,000,000
2015								500,000,000	100,000,000
2016								500,000,000
Thereafter								6,800,000,000	500,000,000
Total commitments								9,200,000,000	700,000,000
Superfund
Number of consumer class action complaints filed		1	2
Number of oil companies				9
Number of power companies				14
Costs related to investigation and study under Superfund site					1,000,000
Southwest Power Outage
Capacity of transmission line that tripped out of service (in kV)					500
Period, after the transmission line went off-line, over which generation and transmission resources for the Yuma area were lost (in minutes)					10
Number of customers losing service in Yuma area					69,700
Capacity of firm load that were reported to have been affected due to outages affecting portions of southern Arizona, southern California and northern Mexico (in MW)					7,900
Number of customers that were reported to have been affected due to outages					2,700,000
Maximum possible fine per violation per day that the violation is found to have been in existence							1,000,000
Financial Assurances
Outstanding letters of credit to support existing variable interest rate pollution control bonds						76,000,000
Letters of credit to support certain equity lessors in the Palo Verde sale leaseback transactions						44,000,000
Letters of credit issued to support natural gas tolling contract obligations						40,000,000
Outstanding letters of credit to support natural gas tolling contract obligations						$ 65,000,000