Commitments and Contingencies (Details 2) (USD $)	9 Months Ended
	Sep. 30, 2011 customer y
Contractual Obligations
Contractual obligations increase	$ 750,000,000
Costs related to investigation and study under Superfund site	1,000,000
Southwest Power Outage
Number of customers that were reported to have been affected due to outages	2,800,000
Purchase obligations
Contractual Obligations
2013	100,000,000
Thereafter	150,000,000
Total	250,000,000
Fuel and purchased power commitments
Contractual Obligations
2011	200,000,000
2013	50,000,000
Total	250,000,000
Renewable energy credits
Contractual Obligations
Thereafter	250,000,000
Total	250,000,000
ARIZONA PUBLIC SERVICE COMPANY
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
Maximum possible fine per violation per day that the violation is found to have been in existence	1,000,000
Period of advance notice of intent to file a lawsuit by a citizens group under the Clean Air Act (in days)	60
Financial Assurances
Outstanding letters of credit to support existing pollution control bonds	44,000,000
Letters of credit to support certain equity lessors in the Palo Verde sale leaseback transactions	52,000,000
Outstanding letters of credit to support natural gas tolling contract obligations	$ 10,000,000
ARIZONA PUBLIC SERVICE COMPANY | United States
Southwest Power Outage
Number of customers that were reported to have been affected due to outages	1,600,000
ARIZONA PUBLIC SERVICE COMPANY | Northern Mexico
Southwest Power Outage
Number of customers that were reported to have been affected due to outages	1,200,000