Regulatory Matters (Details) (USD $)	3 Months Ended				0 Months Ended	1 Months Ended			1 Months Ended	0 Months Ended	3 Months Ended				0 Months Ended		3 Months Ended				1 Months Ended		3 Months Ended		0 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014 APS	Mar. 31, 2013 APS	Dec. 03, 2013 APS ACC Net Metering	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. 30, 2013 Filing with the Arizona Corporation Commission APS ACC Residential customers rate case filing	Mar. 31, 2014 Cost Recovery Mechanisms Power Supply Adjustor (PSA)	Mar. 31, 2014 Cost Recovery Mechanisms APS 2013 DSMAC	Dec. 31, 2012 Cost Recovery Mechanisms APS 2013 DSMAC	Mar. 31, 2014 Cost Recovery Mechanisms APS 2014 DSMAC	Mar. 02, 2014 Cost Recovery Mechanisms APS Lost Fixed Cost Recovery Mechanism	Feb. 12, 2013 Cost Recovery Mechanisms APS Lost Fixed Cost Recovery Mechanism	Mar. 31, 2014 Cost Recovery Mechanisms APS Lost Fixed Cost Recovery Mechanism	Mar. 31, 2014 Cost Recovery Mechanisms APS ACC RES	Jun. 02, 2012 Cost Recovery Mechanisms APS ACC 2013 DSMAC	Jul. 12, 2013 Cost Recovery Mechanisms APS ACC RES implementation plan covering 2014-2018 timeframe	Feb. 28, 2014 Cost Recovery Mechanisms APS ACC Power Supply Adjustor (PSA)	Feb. 28, 2013 Cost Recovery Mechanisms APS ACC Power Supply Adjustor (PSA)	Mar. 31, 2014 Cost Recovery Mechanisms APS ACC Power Supply Adjustor (PSA)	Mar. 31, 2013 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
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%
Approximate percentage of increase in the average retail customer bill under proposed Four Corners rate filing										2.00%
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
Change in regulatory asset
Plan term																		5 years
Amount of proposed budget													87,600,000							143,000,000
Amount of approved budget												68,900,000		68,900,000
Percentage of cumulative energy savings for current year																			5.00%
Beginning balance																							21,000,000	73,000,000
Deferred fuel and purchased power costs-current period	(31,630,000)	(31,194,000)	(31,630,000)	(31,194,000)																			(32,000,000)	(31,000,000)
Amounts charged to customers	(8,022,000)	(1,122,000)	(8,022,000)	(1,122,000)																			(8,000,000)	(1,000,000)
Ending balance																							(19,000,000)	41,000,000
Charge on future customers who install rooftop solar panels (in dollars per kWh)					0.70
Estimated monthly collection due to charge on future customers who install rooftop solar panels					4.90
PSA rate (in dollars per kWh)																					0.001557
PSA rate for prior year (in dollars per kWh)																						0.001329
Forward component of increase in PSA (in dollars per kWh)											0.001277
Historical component of increase in PSA (in dollars per kWh)											0.000280
Increase in annual wholesale transmission rates																									26,000,000
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															$ 25,300,000	$ 5,100,000