SEGMENT AND RELATED INFORMATION - Southern Power (Details) $ in Millions	12 Months Ended
	Dec. 31, 2024 USD ($) segment	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Segment Reporting Information [Line Items]
Other segment items	$ 13,995	$ 13,954	$ 19,426
Total operating revenues	$ 26,724	25,253	29,279
SOUTHERN POWER CO
Segment Reporting Information [Line Items]
Number of reportable segments | segment	1
Total operating revenues	$ 2,014	2,189	3,369
SOUTHERN POWER CO | Wholesale revenues, affiliates
Segment Reporting Information [Line Items]
Total operating revenues	$ 371	537	875
Alabama Power
Segment Reporting Information [Line Items]
Number of reportable segments | segment	1
Total operating revenues	$ 7,554	7,050	7,817
Alabama Power | Wholesale revenues, affiliates
Segment Reporting Information [Line Items]
Total operating revenues	$ 139	60	202
Georgia Power
Segment Reporting Information [Line Items]
Number of reportable segments | segment	1
Total operating revenues	$ 11,331	10,118	11,584
Mississippi Power
Segment Reporting Information [Line Items]
Number of reportable segments | segment	1
Total operating revenues	$ 1,463	1,474	1,694
Mississippi Power | Wholesale revenues, affiliates
Segment Reporting Information [Line Items]
Total operating revenues	218	200	460
Reportable Segment | SOUTHERN POWER CO
Segment Reporting Information [Line Items]
Other segment items	1,100	1,200	2,300
Reportable Segment | Alabama Power
Segment Reporting Information [Line Items]
Other segment items	2,125	2,098	2,915
Total operating revenues	7,554	7,050	7,817
Reportable Segment | Georgia Power
Segment Reporting Information [Line Items]
Other segment items	3,476	3,382	5,249
Total operating revenues	11,331	10,118	11,584
Reportable Segment | Mississippi Power
Segment Reporting Information [Line Items]
Other segment items	$ 900	$ 1,000	$ 1,300