Regulatory Matters (Details) (USD $)	3 Months Ended		0 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Jan. 01, 2014	Jan. 06, 2012	Jun. 01, 2011	Jan. 15, 2015	Jan. 15, 2014	Feb. 12, 2013	Feb. 01, 2015	Feb. 01, 2014	Jun. 01, 2014	Apr. 02, 2015	Apr. 15, 2014 Customer MW	Dec. 31, 2012	Jun. 01, 2012	Dec. 31, 2014	Jul. 01, 2014	Jul. 12, 2013
Change in regulatory asset
Deferred fuel and purchased power costs-current period	$ 17,671,000	$ 31,630,000
Amounts charged to customers	5,614,000	8,022,000
APS
Change in regulatory asset
Deferred fuel and purchased power costs-current period	17,671,000	31,630,000
Amounts charged to customers	5,614,000	8,022,000
APS | Lost Fixed Cost Recovery Mechanism
Change in regulatory asset
Percentage of retail revenues	1.00%
APS | ACC | Net Metering
Change in regulatory asset
Charge on future customers who install rooftop solar panels (in dollars per kWh)	0.70		0.70
Estimated monthly collection due to charge on future customers who install rooftop solar panels			4.90
Filing with the Arizona Corporation Commission | APS | ACC | Retail rate case filing
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%
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
Filing with the Arizona Corporation Commission | APS | ACC | Retail rate case filing | Maximum
Settlement Agreement
Annual cost recovery due to modifications to the Environmental Improvement Surcharge				5,000,000
Cost Recovery Mechanisms | APS | 2013 DSMAC
Settlement Agreement
Amount of proposed budget														87,600,000
Amount of approved budget	68,900,000
Cost Recovery Mechanisms | APS | 2014 DSMAC
Settlement Agreement
Amount of approved budget	68,900,000
Cost Recovery Mechanisms | APS | 2015 DSMAC
Settlement Agreement
Amount of proposed budget	68,900,000
Cost Recovery Mechanisms | APS | Lost Fixed Cost Recovery Mechanism
Change in regulatory asset
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						38,500,000	25,300,000	5,100,000
Cost Recovery Mechanisms | APS | ACC | RES
Settlement Agreement
Plan term	5 years
Cost Recovery Mechanisms | APS | ACC | 2013 DSMAC
Settlement Agreement
Percentage of cumulative energy savings for current year															5.00%
Cost Recovery Mechanisms | APS | ACC | RES implementation plan covering 2014-2018 timeframe
Settlement Agreement
Amount of proposed budget																	154,000,000	143,000,000
Amount of approved budget																152,000,000
Cost Recovery Mechanisms | APS | ACC | Power Supply Adjustor (PSA)
Change in regulatory asset
Beginning balance	7,000,000	21,000,000	21,000,000
Deferred fuel and purchased power costs-current period	(18,000,000)	(32,000,000)
Amounts charged to customers	(5,000,000)	(8,000,000)
Ending balance	(16,000,000)	(19,000,000)
PSA rate (in dollars per kWh)									0.000887
PSA rate for prior year (in dollars per kWh)										0.001557
Forward component of increase in PSA (in dollars per kWh)									0.001131
Historical component of increase in PSA (in dollars per kWh)									(0.000244)
Cost Recovery Mechanisms | APS | FERC | Transmission Rates, Transmission Cost Adjustor and Other Transmission Matters
Change in regulatory asset
Increase in annual wholesale transmission rates											5,900,000
Subsequent Event | APS | ACC | Net Metering
Change in regulatory asset
Charge on future customers who install rooftop solar panels (in dollars per kWh)												0.70
Proposed fixed grid access charge on new residential solar customers (in dollars per KWh)												3.00
Estimated monthly collection due to charge on new residential solar customers												$ 21
AZ Sun Program | Filing with the Arizona Corporation Commission | APS | 2014 RES
Settlement Agreement
Request to build additional utility scale solar, capacity													20
Alternative to AZ Sun Program | Filing with the Arizona Corporation Commission | APS | 2014 RES
Settlement Agreement
Request to build additional utility scale solar, capacity													10
Additional capacity from APS-owned non AZ Sun projects, impacted customers													1,500
Alternative to AZ Sun Program, Phase 1 | Filing with the Arizona Corporation Commission | APS | 2014 RES
Settlement Agreement
Request to build additional utility scale solar, capacity													8
Alternative to AZ Sun Program Phase 2 | Filing with the Arizona Corporation Commission | APS | 2014 RES
Settlement Agreement
Request to build additional utility scale solar, capacity													2