Introduction - Schedule of Goodwill (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Goodwill [Line Items]
Goodwill	$ 5,161	$ 5,161
SOUTHERN Co GAS
Goodwill [Line Items]
Goodwill	5,015	5,015
SOUTHERN Co GAS \| Gas distribution operations
Goodwill [Line Items]
Goodwill	4,034	4,034
SOUTHERN Co GAS \| Gas marketing services
Goodwill [Line Items]
Goodwill	$ 981	$ 981

Amount, after accumulated impairment loss, of asset representing future economic benefit arising from other asset acquired in business combination or from joint venture formation or both, that is not individually identified and separately recognized.

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+ Details

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

SOUTHERN CO 10-Q