ASSET RETIREMENT OBLIGATIONS - Fair Value Increases (Decreases) of the Funds (Details) - Securities held in the Funds - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Fair value increases
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Fair value increases (decreases) of the Funds	$ 348	$ 229	$ 281
Unrealized gains
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Fair value increases (decreases) of the Funds	216	113	241
Alabama Power | Fair value increases
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Fair value increases (decreases) of the Funds	191	143	157
Alabama Power | Unrealized gains
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Fair value increases (decreases) of the Funds	111	64	119
Georgia Power | Fair value increases
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Fair value increases (decreases) of the Funds	157	86	124
Georgia Power | Unrealized gains
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Fair value increases (decreases) of the Funds	$ 105	$ 49	$ 122