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