STOCK COMPENSATION - Schedule of Employees Participating in Stock-Based Compensation Programs (Details)	Dec. 31, 2021 employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of employees	1,728
Alabama Power
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of employees	241
Georgia Power
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of employees	271
Mississippi Power
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of employees	70
Southern Power
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of employees	45
Southern Company Gas
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of employees	173