PROPERTY, PLANT, AND EQUIPMENT - Southern Power Useful Lives (Details) - Southern Power - Maximum	12 Months Ended
Dec. 31, 2021
Natural Gas Generating Facility
Property, Plant and Equipment [Line Items]
Useful life	50 years
Solar Generating Facility
Property, Plant and Equipment [Line Items]
Useful life	35 years
Wind Generating Facility
Property, Plant and Equipment [Line Items]
Useful life	30 years

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration