PROPERTY, PLANT, AND EQUIPMENT - Property, Plant and Equipment (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Electric utilities:
Generation	$ 57,325	$ 51,756
Transmission	15,561	14,201
Distribution	26,482	24,200
General/other	6,305	5,806
Electric utilities' plant in service	105,673	95,963
Southern Company Gas:
Natural gas transportation and distribution	17,798	16,810
Storage facilities	1,565	1,553
Other	1,477	1,360
Southern Company Gas plant in service	20,840	19,723
Other plant in service	1,915	1,843
Total plant in service	128,428	117,529
Alabama Power
Electric utilities:
Generation	16,584	15,920
Transmission	6,152	5,658
Distribution	9,775	9,154
General/other	2,918	2,740
Electric utilities' plant in service	35,429	33,472
Southern Company Gas:
Natural gas transportation and distribution	0	0
Storage facilities	0	0
Other	0	0
Southern Company Gas plant in service	0	0
Other plant in service	0	0
Total plant in service	35,429	33,472
Georgia Power
Electric utilities:
Generation	22,587	17,755
Transmission	8,402	7,576
Distribution	15,380	13,819
General/other	3,001	2,729
Electric utilities' plant in service	49,370	41,879
Southern Company Gas:
Natural gas transportation and distribution	0	0
Storage facilities	0	0
Other	0	0
Southern Company Gas plant in service	0	0
Other plant in service	0	0
Total plant in service	49,370	41,879
Mississippi Power
Electric utilities:
Generation	2,909	2,826
Transmission	966	927
Distribution	1,327	1,228
General/other	321	273
Electric utilities' plant in service	5,523	5,254
Southern Company Gas:
Natural gas transportation and distribution	0	0
Storage facilities	0	0
Other	0	0
Southern Company Gas plant in service	0	0
Other plant in service	0	0
Total plant in service	5,523	5,254
Southern Power
Electric utilities:
Generation	14,649	14,619
Transmission	0	0
Distribution	0	0
General/other	41	39
Electric utilities' plant in service	14,690	14,658
Southern Company Gas:
Natural gas transportation and distribution	0	0
Storage facilities	0	0
Other	0	0
Southern Company Gas plant in service	0	0
Other plant in service	0	0
Total plant in service	14,690	14,658
Southern Company Gas
Electric utilities:
Generation	0	0
Transmission	0	0
Distribution	0	0
General/other	0	0
Electric utilities' plant in service	0	0
Southern Company Gas:
Natural gas transportation and distribution	17,798	16,810
Storage facilities	1,565	1,553
Other	1,477	1,360
Southern Company Gas plant in service	20,840	19,723
Other plant in service	0	0
Total plant in service	$ 20,840	$ 19,723