Regulatory Matters - Capital Structure and Costs of Capital (Details) - $ / kWh	Oct. 01, 2021	May 01, 2020	Oct. 31, 2019	May 01, 2019	May 01, 2018
Cost of Capital
Long-term debt			4.10%
Common stock equity			10.15%
Weighted-average cost of capital			7.41%
Retail Rate Case Filing with Arizona Corporation Commission | APS
Capital Structure
Common stock equity			54.70%
Retail Rate Case Filing with Arizona Corporation Commission | ACC | APS
Capital Structure
Long-term debt			45.30%
Net Metering | ACC | APS
Cost of Capital
Second-year export energy price (in dollars per kWh)		0.094		0.105	0.116
Net Metering | ACC | APS | Forecast
Cost of Capital
Second-year export energy price (in dollars per kWh)	10.5