Regulatory Matters - Narrative (Details)																						1 Months Ended	12 Months Ended
	Feb. 15, 2019 USD ($)	Feb. 01, 2019 $ / kWh	Aug. 13, 2018 USD ($)	Jun. 01, 2018 USD ($)	May 01, 2018 $ / kWh	Feb. 22, 2018 USD ($)	Feb. 20, 2018	Feb. 15, 2018 USD ($)	Feb. 01, 2018 $ / kWh	Jan. 08, 2018 USD ($)	Nov. 20, 2017 USD ($)	Aug. 19, 2017 $ / kWh	Jun. 01, 2017 USD ($)	Feb. 01, 2017 $ / kWh	Jan. 13, 2017 USD ($)	Dec. 20, 2016 $ / kWh	Jun. 01, 2016 USD ($)	Feb. 01, 2016 $ / kWh	Jan. 15, 2016 USD ($)	Feb. 01, 2015 $ / kWh	Jun. 01, 2011 USD ($)	Dec. 31, 2014 penetration_feeder storage_system MW	Dec. 31, 2018 USD ($) $ / kWh	Dec. 31, 2017 USD ($)	Dec. 31, 2012 $ / kWh	Jun. 29, 2018 USD ($)	Nov. 14, 2017 USD ($)	Sep. 01, 2017 USD ($)	Jun. 30, 2017 USD ($)	Jan. 27, 2017 USD ($)	Jul. 01, 2016 USD ($)	Nov. 25, 2015 USD ($)	Mar. 20, 2015 project
Regulatory Matters [Line Items]
Ballot initiative, proposed required energy supply to be obtained from renewable sources (as a percent)							50.00%
ARIZONA PUBLIC SERVICE COMPANY
Regulatory Matters [Line Items]
Requested rate decrease for tax act																								$ (377,000,000)
ARIZONA PUBLIC SERVICE COMPANY | Lost Fixed Cost Recovery Mechanism
Regulatory Matters [Line Items]
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
Fixed costs recoverable per power lost (in dollars per kWh) | $ / kWh																							0.025
Rate matter cap percentage of retail revenue																							1.00%
Amount of adjustment approved representing prorated sales losses															$ 63,700,000				$ 46,400,000
Increase in amount of adjustment representing prorated sales losses															$ 17,300,000				$ 7,900,000
Amount of adjustment approved representing prorated sales losses pending approval								$ 60,700,000
Decrease in amount of adjustment representing prorated sales losses								$ 3,000,000
ARIZONA PUBLIC SERVICE COMPANY | ACC
Regulatory Matters [Line Items]
Requested rate decrease for tax act			$ 86,500,000							$ 119,100,000
Approved rate decrease for tax act						$ 119,100,000
ARIZONA PUBLIC SERVICE COMPANY | ACC | Retail Rate Case Filing with Arizona Corporation Commission
Regulatory Matters [Line Items]
Net retail rate increase																	$ 165,900,000				$ 95,500,000
ARIZONA PUBLIC SERVICE COMPANY | ACC | Arizona Renewable Energy Standard and Tariff 2017
Regulatory Matters [Line Items]
Amount of approved budget																															$ 150,000,000
ARIZONA PUBLIC SERVICE COMPANY | ACC | Arizona Renewable Energy Standard and Tariff 2018
Regulatory Matters [Line Items]
Amount of proposed budget																										$ 89,900,000			$ 90,000,000
ARIZONA PUBLIC SERVICE COMPANY | ACC | 2015 DSMAC
Regulatory Matters [Line Items]
Amount of approved budget																																$ 68,900,000
Rate matter number of resource savings projects | project																																	3
ARIZONA PUBLIC SERVICE COMPANY | ACC | 2017 DSMAC
Regulatory Matters [Line Items]
Amount of proposed budget																	$ 62,600,000
Amount of approved budget																														$ 66,600,000
ARIZONA PUBLIC SERVICE COMPANY | ACC | Demand Side Management Adjustor Charge 2018
Regulatory Matters [Line Items]
Amount of proposed budget																							$ 34,100,000				$ 52,600,000	$ 52,600,000
ARIZONA PUBLIC SERVICE COMPANY | ACC | Power Supply Adjustor (PSA)
Regulatory Matters [Line Items]
Maximum increase (decrease) in PSA rate (in dollars per kWh) | $ / kWh									0.004
Fuel And purchased power costs, excess annual limit																							$ 16,400,000
PSA rate (in dollars per kWh) | $ / kWh									0.004555			0.000555		(0.001348)
Forward component of PSA rate (in dollars per kWh) | $ / kWh									0.002009			0.000876		(0.001027)
Historical component of PSA rate (in dollars per kWh) | $ / kWh									0.002546			(0.000321)		(0.000321)
ARIZONA PUBLIC SERVICE COMPANY | ACC | Net Metering
Regulatory Matters [Line Items]
Cost of service, resource comparison proxy method, maximum annual percentage decrease																10.00%
Cost of service for interconnected DG system customers, grandfathered period																20 years
Guaranteed export price period																10 years
Settlement agreement, energy price for exported energy (in dollars per kWh) | $ / kWh																0.129
Request second-year energy price for exported energy | $ / kWh					0.116
ARIZONA PUBLIC SERVICE COMPANY | FERC | Transmission rates, transmission cost adjustor and other transmission matters
Regulatory Matters [Line Items]
Increase (decrease) in annual wholesale transmission rates													$ 35,100,000
Rate Matters, Increase (Decrease) in Cost Recovery				$ (22,700,000)
Cost Recovery Mechanisms | ARIZONA PUBLIC SERVICE COMPANY | ACC | Power Supply Adjustor (PSA)
Regulatory Matters [Line Items]
Maximum increase (decrease) in PSA rate (in dollars per kWh) | $ / kWh																				0.004
PSA Rate in Prior Years (decrease) | $ / kWh																		0.001678
Subsequent Event | ARIZONA PUBLIC SERVICE COMPANY | Lost Fixed Cost Recovery Mechanism
Regulatory Matters [Line Items]
Amount of adjustment approved representing prorated sales losses pending approval	$ 36,200,000
Decrease in amount of adjustment representing prorated sales losses	$ 24,500,000
Subsequent Event | ARIZONA PUBLIC SERVICE COMPANY | ACC | Power Supply Adjustor (PSA)
Regulatory Matters [Line Items]
PSA rate (in dollars per kWh) | $ / kWh		0.001658
Forward component of PSA rate (in dollars per kWh) | $ / kWh		0.000536
Historical component of PSA rate (in dollars per kWh) | $ / kWh		0.001122
Subsequent Event | Cost Recovery Mechanisms | ARIZONA PUBLIC SERVICE COMPANY | ACC | Power Supply Adjustor (PSA)
Regulatory Matters [Line Items]
PSA Rate in Prior Years (decrease) | $ / kWh		(0.002897)
Alternative to AZ Sun Program, Phase 1 | ARIZONA PUBLIC SERVICE COMPANY | Arizona Renewable Energy Standard and Tariff 2014
Regulatory Matters [Line Items]
Rate matter additional capacity from AZ Sun projects | MW																						8
Solar Partner Program Phase 2 | ARIZONA PUBLIC SERVICE COMPANY | Arizona Renewable Energy Standard and Tariff 2014
Regulatory Matters [Line Items]
Rate matter additional capacity from AZ Sun projects | MW																						2
Solar storage system, capacity (in MW) | MW																						2
Number of energy storage systems | storage_system																						2
Number of high solar penetration feeders | penetration_feeder																						2
Solar Communities | ARIZONA PUBLIC SERVICE COMPANY | ACC | Arizona Renewable Energy Standard and Tariff 2018
Regulatory Matters [Line Items]
Program term											3 years
Minimum | Solar Communities | ARIZONA PUBLIC SERVICE COMPANY | ACC | Arizona Renewable Energy Standard and Tariff 2018
Regulatory Matters [Line Items]
Required annual capital investment											$ 10,000,000
Maximum | Solar Communities | ARIZONA PUBLIC SERVICE COMPANY | ACC | Arizona Renewable Energy Standard and Tariff 2018
Regulatory Matters [Line Items]
Required annual capital investment											$ 15,000,000