Commitments and Contingencies (Details 2) (USD $) In Millions, unless otherwise specified	1 Months Ended		3 Months Ended		3 Months Ended
	Feb. 29, 2008 Climate Change Lawsuit item	Sep. 30, 2011 ARIZONA PUBLIC SERVICE COMPANY kW item MW	Mar. 31, 2013 ARIZONA PUBLIC SERVICE COMPANY item	Sep. 08, 2011 ARIZONA PUBLIC SERVICE COMPANY	Mar. 31, 2013 ARIZONA PUBLIC SERVICE COMPANY Contaminated groundwater wells item
Superfund-Related Matters
Costs related to investigation and study under Superfund site			$ 2
Number of defendants against whom Roosevelt Irrigation District ("RID") filed lawsuit					40
Number of oil companies	9
Number of power companies	14
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		10 minutes
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
Number of letters of credit expiring in 2015			1
Number of letters of credit expiring in 2016			2
Letters of credit to support certain equity lessors in the Palo Verde sale leaseback transactions			34
Outstanding letters of credit to support natural gas tolling contract obligations			$ 65