Regulatory Matters - ACC General Retail Rate Cases (Details) $ in Millions	Apr. 03, 2026 USD ($)	Mar. 18, 2026 USD ($)	Mar. 02, 2026 USD ($)	Jun. 13, 2025 USD ($) $ / KWH_Kilowatt_hour	Feb. 22, 2024 USD ($)	Mar. 31, 2026
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount		$ 525.2
Increment of fair value rate, percentage			0.00%
Requested period of post-test year plant		12 months
Approved rate increase (decrease), amount					$ 491.7
Minimum
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount			$ 200.2
Requested return on equity, percentage		9.55%	9.00%
Requested period of post-test year plant			0 months
Maximum
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount			$ 278.1
Requested return on equity, percentage		9.80%	9.20%
Requested period of post-test year plant			12 months
APS
Public Utilities, General Disclosures [Line Items]
Increment of fair value rate, percentage						1.00%
APS | Subsequent Event
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount	$ 694.2
Requested return on equity, percentage	10.70%
Increment of fair value rate, percentage	0.90%
Requested period of post-test year plant	12 months
Requested net revenue requirement increase (decrease), amount	$ 611.3
Requested increase (decrease) in deadband	0.0040
Requested projected plant duration	6 months
Requested review and challenge period	120 days
ACC
Public Utilities, General Disclosures [Line Items]
Increment of fair value rate, percentage		0.20%			0.25%
Approved return on equity, percentage					9.55%
ACC | APS
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount				$ 579.5
Total revenue deficiency				$ 662.4
ACC | APS | Rate Case Filing with Arizona Corporation Commission
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), percentage				13.99%
Public utilities, test period				12 months
Rate matter, cost base rate				$ 12,500.0
Effective fair value percentage					4.39%
ACC | ACC | Rate Case Filing with Arizona Corporation Commission
Public Utilities, General Disclosures [Line Items]
Base fuel and purchased power costs rate (in dollars per kWh) | $ / KWH_Kilowatt_hour				0.043881