INCOME TAXES - Amortization of Deferred Credits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Line Items]
Amortization of investment tax credits	$ 84	$ 83	$ 84
Southern Power
Income Tax Disclosure [Line Items]
Amortization of investment tax credits	$ 58	$ 58	$ 58