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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 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

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- Definition Amount of Adjustment Representing Prorated Sales Losses Approved + References No definition available. + Details
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- Definition Amount of Adjustment Representing Prorated Sales Losses Pending Approval + References No definition available. + Details
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- Definition Represents the forward component of increase in PSA. + References No definition available. + Details
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- Definition Represents the historical component of increase in PSA. + References No definition available. + Details
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- Definition Represents the PSA rate (power supply adjustor) which provides for the adjustment of retail rates to reflect variations in retail fuel and purchased power costs. + References No definition available. + Details
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- Definition Represents the PSA rate prior for the prior years (power supply adjustor) which provides for the adjustment of retail rates to reflect variations in retail fuel and purchased power costs. + References No definition available. + Details
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- Definition Approximate percentage of increase in the average retail customer bill due to request for net retail base rate increase. + References No definition available. + Details
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- Definition Represents the Charge on future customers who install rooftop solar panels under order issued on net metering proposal. + References No definition available. + Details
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- Definition Represents the amount of estimated monthly collection due to charge on future customers who install rooftop solar panels under order issued on net metering proposal. + References No definition available. + Details
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