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

Regulatory Matters - Alabama Power (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2026	Dec. 31, 2026	Mar. 31, 2026	Dec. 31, 2025
Loss Contingencies [Line Items]
In service	$ 151,437			$ 146,114
ALABAMA POWER CO
Loss Contingencies [Line Items]
In service	40,731			38,915
ALABAMA POWER CO \| Plant Barry Unit 5
Loss Contingencies [Line Items]
In service			$ 307
SOUTHERN POWER CO
Loss Contingencies [Line Items]
In service	15,339			$ 15,034
SOUTHERN POWER CO \| Plant Barry Unit 5
Loss Contingencies [Line Items]
In service			$ 307
Reliability Reserve Liability \| ALABAMA POWER CO
Loss Contingencies [Line Items]
Remaining net book value	144
Reliability reserve expense	$ 40
Reliability Reserve Liability \| ALABAMA POWER CO \| Scenario, Forecast
Loss Contingencies [Line Items]
Reliability reserve expense		$ 60