Regulatory Matters - Retail Rate Case Filing (Details) - Retail Rate Case Filing with Arizona Corporation Commission - ACC - ARIZONA PUBLIC SERVICE COMPANY	Jan. 03, 2018 Customer	Nov. 13, 2017 USD ($)	Mar. 27, 2017 USD ($) $ / kWh	Mar. 26, 2017 $ / kWh	Jun. 01, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jun. 01, 2011 USD ($)
Public Utilities, General Disclosures [Line Items]
Net retail rate increase					$ 165,900,000		$ 95,500,000
Adjuster account balance transferred into base rates						$ 267,600,000
Approximate percentage of increase in average customer bill			3.28%		5.74%
Approximate percentage of increase in average residential customer bill			4.54%		7.96%
Settlement agreement, net retail base rate increase			$ 94,600,000
Settlement agreement, non-fuel, non-depreciation, base rate increase			87,200,000
Fuel-related base rate decrease			53,600,000
Base rate increase, changes in depreciation schedules			$ 61,000,000.0
Authorized return on common equity (as a percent)			10.00%
Percentage of debt in capital structure			44.20%
Percentage of common equity in capital structure			55.80%
Environmental surcharge cap rate (in dollars per kWh) | $ / kWh			0.00050	0.00016
Resource comparison proxy for exported energy (in dollars per kWh) | $ / kWh			0.129
Monthly metering infrastructure opt-out fee		$ 5
Number of customers which signed complaint | Customer	25
AZ Sun II Program
Public Utilities, General Disclosures [Line Items]
Minimum annual renewable energy standard and tariff			$ 10,000,000
Maximum annual renewable energy standard and tariff			$ 15,000,000