REGULATORY MATTERS - APC Rate NDR (Details) - Alabama Power - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2021
Public Utilities, General Disclosures [Line Items]
Minimum natural disaster reserve balance, triggering establishment charge			$ 50,000,000
Natural disaster reserve authorized limit			$ 75,000,000			$ 50,000,000
Maximum period for recovery deferred stock related operations and maintenance costs and any future reserve deficits			24 months
Maximum rate NDR charge per month, monthly nonresidential customer account			$ 10
Maximum rate NDR charge per month, monthly residential customer account			5
Additional accruals authorized by state PSCs			65,000,000	$ 100,000,000	$ 84,000,000
Annual recovery amount			6,000,000	5,000,000	$ 16,000,000
Regulatory asset, amortization period			$ 103,000,000	$ 77,000,000
Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
NDR, expected recovery amount	$ 3,000,000	$ 8,000,000