Introduction - Storm Damage Reserves (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance at December 31, 2023	$ 66
Balance at March 31, 2024	63
Accrued Storm Reserve
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Accrual	14
Storm Reserve
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Weather-related damages	(17)
ALABAMA POWER CO
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance at December 31, 2023	76
Balance at March 31, 2024	74
ALABAMA POWER CO | Accrued Storm Reserve
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Accrual	3
ALABAMA POWER CO | Storm Reserve
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Weather-related damages	(5)
GEORGIA POWER CO
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance at March 31, 2024	(58)	$ (54)
GEORGIA POWER CO | Accrued Storm Reserve
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Accrual	8
GEORGIA POWER CO | Storm Reserve
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Weather-related damages	(12)
MISSISSIPPI POWER CO
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance at December 31, 2023	44
Balance at March 31, 2024	47
MISSISSIPPI POWER CO | Accrued Storm Reserve
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Accrual	3
MISSISSIPPI POWER CO | Storm Reserve
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Weather-related damages	$ 0