Regulatory Matters (Details) signature in Thousands											2 Months Ended	3 Months Ended			12 Months Ended
	Apr. 15, 2016 signature	Feb. 01, 2016 $ / kWh	Jan. 15, 2016 USD ($)	Jun. 01, 2015 USD ($)	Mar. 02, 2015 USD ($)	Apr. 15, 2014 Customer MW	Mar. 01, 2014 USD ($)	Jan. 01, 2014 USD ($) $ / kWh	Jan. 06, 2012 USD ($) $ / kWh	Jun. 01, 2011 USD ($)	Apr. 30, 2014 workshop	Mar. 31, 2016 USD ($) $ / kWh	Jan. 31, 2016 $ / kWh	Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($) $ / kWh	Apr. 01, 2016 USD ($)	Jan. 12, 2016 USD ($)	Nov. 25, 2015 USD ($)	Mar. 20, 2015 project	Dec. 31, 2014 USD ($)	Dec. 19, 2014 MW	Jul. 01, 2014 USD ($)
Change in regulatory asset
Deferred fuel and purchased power costs — current period												$ (1,007,000)		$ (17,671,000)
Amounts charged to customers												(2,388,000)		(5,614,000)
APS
Change in regulatory asset
Deferred fuel and purchased power costs — current period												(1,007,000)		(17,671,000)
Amounts charged to customers												$ (2,388,000)		(5,614,000)
APS | Filing with the Arizona Corporation Commission | ACC | Retail rate case filing
Public Utilities, General Disclosures [Line Items]
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) | $ / kWh									0.03757
Approved base fuel rate (in dollars per kWh) | $ / 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
APS | Filing with the Arizona Corporation Commission | ACC | Retail rate case filing | Maximum
Settlement Agreement
Annual cost recovery due to modifications to the Environmental Improvement Surcharge									$ 5,000,000
APS | RES | Cost Recovery Mechanisms | ACC
Settlement Agreement
Plan term												5 years
APS | 2014 RES | AZ Sun Program | Filing with the Arizona Corporation Commission
Settlement Agreement
Request to build additional utility scale solar, capacity | MW						20
APS | 2014 RES | Alternative to AZ Sun Program | Filing with the Arizona Corporation Commission
Settlement Agreement
Request to build additional utility scale solar, capacity | MW						10
Additional capacity from APS-owned non AZ Sun projects, impacted customers | Customer						1,500
APS | 2014 RES | Alternative to AZ Sun Program, Phase 1 | Filing with the Arizona Corporation Commission
Settlement Agreement
Request to build additional utility scale solar, capacity | MW																					8
APS | 2014 RES | Alternative to AZ Sun Program Phase 2 | Filing with the Arizona Corporation Commission
Settlement Agreement
Request to build additional utility scale solar, capacity | MW																					2
APS | 2015 RES | Cost Recovery Mechanisms | ACC
Settlement Agreement
Amount of proposed budget																						$ 154,000,000
Amount of approved budget																				$ 152,000,000
APS | 2016 RES | Cost Recovery Mechanisms | ACC
Settlement Agreement
Amount of approved budget																	$ 148,000,000
APS | 2015 DSMAC | Cost Recovery Mechanisms | ACC
Settlement Agreement
Amount of approved budget																		$ 68,900,000
Number of resource savings projects | project																			3
APS | 2016 DSMAC | Cost Recovery Mechanisms | ACC
Settlement Agreement
Amount of proposed budget				$ 68,900,000
APS | Electric energy efficiency standard | ACC
Settlement Agreement
Number of workshops | workshop											3
APS | Power Supply Adjustor (PSA) | Cost Recovery Mechanisms | ACC
Change in regulatory asset
Beginning balance												$ (9,688,000)		6,925,000	$ 6,925,000
Deferred fuel and purchased power costs — current period												(1,007,000)		(17,671,000)
Amounts charged to customers												(2,388,000)		(5,614,000)
Ending balance												$ (13,083,000)		$ (16,360,000)	$ (9,688,000)
PSA rate (in dollars per kWh) | $ / kWh		0.001678
PSA rate for prior year (in dollars per kWh) | $ / kWh															0.000887
Forward component of increase in PSA (in dollars per kWh) | $ / kWh		0.001975
Historical component of increase in PSA (in dollars per kWh) | $ / kWh		(0.000297)
Transition component increase in PSA (in dollars per kWh) | $ / kWh													(0.004936)
APS | Transmission Rates, Transmission Cost Adjustor and Other Transmission Matters | Cost Recovery Mechanisms | FERC
Change in regulatory asset
Increase in annual wholesale transmission rates				$ 17,600,000
APS | Lost Fixed Cost Recovery Mechanism
Change in regulatory asset
Percentage of retail revenues												1.00%
APS | Lost Fixed Cost Recovery Mechanism | Cost Recovery Mechanisms
Change in regulatory asset
Fixed costs recoverable per residential power lost (in dollars per kWh) | $ / kWh												0.031
Fixed costs recoverable per non-residential power lost (in dollars per kWh) | $ / kWh												0.023
Amount of adjustment representing prorated sales losses approval					$ 38,500,000		$ 25,300,000
Amount of adjustment representing prorated sales losses pending approval			$ 46,400,000
Increase in amount of adjustment representing prorated sales losses			$ 7,900,000
APS | Net Metering | ACC
Change in regulatory asset
Charge on future customers who install rooftop solar panels (in dollars per kWh) | $ / kWh								0.70				0.70
Estimated monthly collection due to charge on future customers who install rooftop solar panels								$ 4.90
Subsequent Event | APS | 2015 DSMAC | Cost Recovery Mechanisms | ACC
Settlement Agreement
Amount of proposed budget																$ 68,900,000
Subsequent Event | APS | Net Metering | Arizona Secretary of State
Change in regulatory asset
Rate benefits preservation initiative, number of signatures required | signature	225