SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES- Storm Damage Reserves (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance at December 31, 2022	$ 216
Balance at December 31, 2023	66
Accrual
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Accrual	61
Weather-related damages
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Weather-related damages	(211)
Alabama Power
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance at December 31, 2022	97
Balance at December 31, 2023	76
Alabama Power | Accrual
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Accrual	18
Alabama Power | Weather-related damages
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Weather-related damages	(39)
Georgia Power
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance at December 31, 2022	83
Balance at December 31, 2023	(54)	$ (83)
Georgia Power | Accrual
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Accrual	31
Georgia Power | Weather-related damages
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Weather-related damages	(168)
Mississippi Power
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance at December 31, 2022	36
Balance at December 31, 2023	44
Mississippi Power | Accrual
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Accrual	12
Mississippi Power | Weather-related damages
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Weather-related damages	$ (4)