Introduction - Schedule of Amortization of Other Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Intangible Asset, Finite-Lived [Line Items]
Amortization of intangible assets	$ 7	$ 8	$ 13	$ 16
Decrease in operating revenues	5	5	10	10
SOUTHERN POWER CO
Intangible Asset, Finite-Lived [Line Items]
Amortization of intangible assets	5	5	10	10
SOUTHERN Co GAS
Intangible Asset, Finite-Lived [Line Items]
Amortization of intangible assets	$ 1	$ 1	$ 2	$ 3

Amount of amortization expense for finite-lived intangible asset. Excludes goodwill and capitalized cost for software to be sold, leased, or marketed.

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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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