Summary of Significant Accounting Policies (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended						12 Months Ended	36 Months Ended	12 Months Ended	36 Months Ended	12 Months Ended
	Dec. 31, 2011 Y	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011 ARIZONA PUBLIC SERVICE COMPANY USDPerkWh trust	Apr. 21, 2011 ARIZONA PUBLIC SERVICE COMPANY Y	Dec. 31, 2008 ARIZONA PUBLIC SERVICE COMPANY Y trust	Dec. 31, 2011 Minimum	Dec. 31, 2011 Minimum	Dec. 31, 2011 Maximum M	Dec. 31, 2011 Maximum	Dec. 31, 2011 Fossil plant Y	Dec. 31, 2011 Nuclear plant Y	Dec. 31, 2011 Other generation Y	Dec. 31, 2011 Transmission Y	Dec. 31, 2011 Distribution Y	Dec. 31, 2011 Other: Y
Approximate remaining average useful lives of utility property
Average useful life (in years)											18	29	28	38	35	7
Extension period of operating licenses for each of the three Palo Verde units (in years)					20	20
Number of VIE lessor trusts				3		3
Depreciation rates (as a percent)	2.98%	2.98%	3.06%					1.30%		10.20%
Allowance for Funds Used During Construction
Composite rate used to calculate AFUDC (as a percent)	10.25%	9.20%	5.90%
Nuclear Fuel
Charges for the permanent disposal of spent nuclear fuel (in dollars per kWh)				0.001
Income Taxes
Percentage of likelihood of realization of recognized tax benefit							50.00%
Cash and Cash Equivalents
Maturity period of highly liquid investments for classification as cash equivalents (in months)									3
Intangible Assets
Amortization expense	$ 47	$ 45	$ 35
Estimated amortization expense on existing intangible assets over the next five years
2012	42
2013	35
2014	28
2015	21
2016	$ 13
Weighted average remaining amortization period for intangible assets (in years)	7
Investments
Ownership percentage for classification as cost method investments by El Dorado									20.00%