Regulatory Matters (Details) (USD $)	9 Months Ended				1 Months Ended			1 Months Ended		3 Months Ended		9 Months Ended	0 Months Ended		0 Months Ended	9 Months Ended		1 Months Ended		1 Months Ended			12 Months Ended			1 Months Ended			1 Months Ended	9 Months Ended		0 Months Ended	1 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 APS	Sep. 30, 2012 APS	Jan. 31, 2012 Filing with the Arizona Corporation Commission APS ACC Retail rate case filing	Jun. 30, 2011 Filing with the Arizona Corporation Commission APS ACC Retail rate case filing	Jan. 06, 2012 Filing with the Arizona Corporation Commission APS ACC Retail rate case filing	Jan. 31, 2012 Filing with the Arizona Corporation Commission APS ACC Retail rate case filing Maximum	Dec. 31, 2009 2008 General Retail Rate Case On-Going Impacts APS ACC	Jun. 30, 2010 2008 General Retail Rate Case On-Going Impacts APS ACC 2008 General retail rate case	Dec. 30, 2009 2008 General Retail Rate Case On-Going Impacts APS ACC 2008 General retail rate case item	Sep. 30, 2013 Cost Recovery Mechanisms Power Supply Adjustor (PSA)	May 01, 2013 Cost Recovery Mechanisms ACC	Dec. 31, 2012 Cost Recovery Mechanisms APS 2013 DSMAC	Feb. 12, 2013 Cost Recovery Mechanisms APS Lost Fixed Cost Recovery Mechanism	Sep. 30, 2013 Cost Recovery Mechanisms APS Lost Fixed Cost Recovery Mechanism	Sep. 30, 2013 Cost Recovery Mechanisms APS ACC RES	Dec. 31, 2011 Cost Recovery Mechanisms APS ACC 2012 RES	Jun. 02, 2012 Cost Recovery Mechanisms APS ACC 2013 DSMAC	Jun. 30, 2012 Cost Recovery Mechanisms APS ACC 2012 DSMAC	Apr. 30, 2012 Cost Recovery Mechanisms APS ACC 2012 DSMAC	Jun. 30, 2011 Cost Recovery Mechanisms APS ACC 2012 DSMAC	Dec. 31, 2009 Cost Recovery Mechanisms APS ACC 2012 DSMAC	Jun. 02, 2011 Cost Recovery Mechanisms APS ACC 2012 DSMAC	Jan. 31, 2013 Cost Recovery Mechanisms APS ACC 2013 RES	Jun. 30, 2012 Cost Recovery Mechanisms APS ACC 2013 RES Maximum	Jun. 30, 2012 Cost Recovery Mechanisms APS ACC 2013 RES Minimum	Jul. 12, 2013 Cost Recovery Mechanisms APS ACC RES implementation plan covering 2014-2018 timeframe	Feb. 28, 2013 Cost Recovery Mechanisms APS ACC Power Supply Adjustor (PSA)	Sep. 30, 2013 Cost Recovery Mechanisms APS ACC Power Supply Adjustor (PSA)	Sep. 30, 2012 Cost Recovery Mechanisms APS ACC Power Supply Adjustor (PSA)	Jun. 01, 2013 Cost Recovery Mechanisms APS FERC Transmission Rates, Transmission Cost Adjustor and Other Transmission Matters	Jun. 30, 2012 Cost Recovery Mechanisms APS FERC Transmission Rates, Transmission Cost Adjustor and Other Transmission Matters
Regulatory Matters
Net retail rate increase						$ 95,500,000
Approximate percentage of increase in the average retail customer bill						6.60%
Settlement Agreement
Net change in base rates					0
Non-fuel base rate increase					116,300,000
Fuel-related base rate decrease					153,100,000
Current base fuel rate (in dollars per kWh)					0.03757
Approved base fuel rate (in dollars per kWh)					0.03207
Estimated amount of transfer of cost recovery for certain renewable energy projects from the RES surcharge to base rates					36,800,000
Authorized return on common equity (as a percent)					10.00%
Percentage of debt in capital structure					46.10%
Percentage of common equity in capital structure					53.90%
Deferral of property taxes in 2012, if Arizona property tax rates increase (as a percent)							25.00%
Deferral of property taxes in 2013, if Arizona property tax rates increase (as a percent)							50.00%
Deferral of property taxes for 2014 and subsequent years, if Arizona property tax rates increase (as a percent)							75.00%
Deferral of property taxes in all years, if Arizona property tax rates decrease (as a percent)							100.00%
Annual cost recovery due to modifications to the Environmental Improvement Surcharge								5,000,000
Elimination of the sharing provision of fuel and purchased power costs					9
Period to process the subsequent rate cases					12 months
ACC staff sufficiency findings, general period of time					30 days
2008 General Retail Rate Case on-going impacts
Number of other parties to the settlement agreement											21
Minimum amount of reduction of average annual operational expenses from 2010 through 2014									30,000,000
Authorization and requirements of equity infusions into APS beginning June 1, 2009 through December 31, 2014									700,000,000
Equity infusions into APS										253,000,000
Change in regulatory asset
Plan term																	5 years
Funding approval as per budget authorized																		110,000,000
Funding request																										107,000,000	97,000,000
Amount of approved budget																									103,000,000
Amount of approved budget for residential distributed energy up-front incentives																									4,000,000
Amount of approved budget for commercial distributed energy up-front incentives																									100,000
Amount of proposed budget														87,600,000														143,000,000
Percentage of cumulative energy savings for prior year																								3.00%
Percentage of annual energy savings to meet energy efficiency goal for 2011																								2.75%
Period of energy savings goal																						2 years
Demand-side management adjustor charge (DSMAC)																					72,000,000
Costs already being recovered in general rates																				10,000,000
Amortization of recovery of demand-side management adjustor charge included in costs already been recovered																							5,000,000
Percentage of cumulative energy savings for current year																			5.00%
Beginning balance																														73,000,000	28,000,000
Deferred fuel and purchased power costs-current period	(13,093,000)	(51,533,000)	(13,093,000)	(51,533,000)																										(13,000,000)	(52,000,000)
Amounts (collected from) credited to customers	(23,158,000)	91,894,000	(23,158,000)	91,894,000																										(23,000,000)	92,000,000
Ending balance																														37,000,000	68,000,000
PSA rate (in dollars per kWh)																													0.0013
PSA rate for prior year (in dollars per kWh)																													(0.0042)
Increase in PSA charge (in dollars per kWh)												0.0055
Forward component of increase in PSA (in dollars per kWh)												(0.0010)
Historical component of increase in PSA (in dollars per kWh)												0.0023
Maximum increase or decrease in PSA charge without permission of the ACC (in dollars per kWh)												0.004
Increase in annual wholesale transmission rates																																26,000,000	16,000,000
Deferred contract termination charges to be amortized over a future period related to proposed acquisition of Southern California Edison													40,000,000
Amortization period													10 years
Fixed costs recoverable per residential power lost (in dollars per kWh)																0.031
Fixed costs recoverable per non-residential power lost (in dollars per kWh)																0.023
Amount of adjustment approved representing prorated sales losses															$ 5,100,000