Commitments and Contingencies (Details 2) (USD $) In Millions, unless otherwise specified	9 Months Ended	1 Months Ended
	Sep. 30, 2012	Feb. 29, 2008 Climate Change Lawsuit item	Sep. 30, 2011 ARIZONA PUBLIC SERVICE COMPANY item	Sep. 30, 2012 ARIZONA PUBLIC SERVICE COMPANY item	Sep. 08, 2011 ARIZONA PUBLIC SERVICE COMPANY	Sep. 30, 2012 Renewable energy credits
Contractual Obligations
Contractual obligations for renewable energy credits increase	$ 215
2012						46
2013						39
2014						44
2015						44
2016						44
Thereafter						573
Total commitments						790
Superfund
Number of oil companies		9
Number of power companies		14
Costs related to investigation and study under Superfund site			2
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
Financial Assurances
Outstanding letters of credit to support existing variable interest rate pollution control bonds				76
Letters of credit to support certain equity lessors in the Palo Verde sale leaseback transactions				42
Outstanding letters of credit to support natural gas tolling contract obligations				$ 65
Number of letters of credit expiring in 2013				2
Number of letters of credit expiring in 2015				1