REGULATORY MATTERS - Schedule of Regulatory Assets and Liabilities (Details) - USD ($) $ in Millions		12 Months Ended			24 Months Ended
	Jan. 01, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2020
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 6,523	$ 5,833		$ 5,833
Regulatory asset amortization period		4 years
Regulatory asset		$ 66	216		216
Plant In Service Net Of Depreciation		(90,703)	(82,232)		(82,232)
Other Regulatory Assets Current		1,120	860		860
Revision of Prior Period, Reclassification, Adjustment
Schedule of Regulatory Assets and Liabilities [Line Items]
Plant In Service Net Of Depreciation			42		42	$ 600
Other Regulatory Assets Current			42		42
Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		2,720	2,340		2,340
Customer refund		304
Regulatory asset		76	97		97
Plant In Service Net Of Depreciation		(24,298)	(23,002)		(23,002)
Other Regulatory Assets Current		385	372		372
Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		5,090	4,663		4,663
Regulatory asset			83		83
Regulatory liabilities		54	83		83
Costs recovered annually		5	12	$ 12
Storm damage reserves	$ 31				213
Plant In Service Net Of Depreciation		(35,415)	(28,764)		(28,764)
Other Regulatory Assets Current		423	324		324
Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		90	4		4
Regulatory asset		44	36		36
Plant In Service Net Of Depreciation		(3,731)	(3,565)		(3,565)
Other Regulatory Assets Current		56	72		72
Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(2,225)	(1,891)		(1,891)
Plant In Service Net Of Depreciation		(15,306)	(14,447)		(14,447)
Other Regulatory Assets Current		141	119		119
Deferred Income Tax Credits
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(4,686)	(5,251)		(5,251)
Deferred Income Tax Credits | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(1,506)	(1,925)		(1,925)
Deferred Income Tax Credits | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(2,161)	(2,244)		(2,244)
Deferred Income Tax Credits | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(241)	(269)		(269)
Regulatory liabilities		11
Deferred Income Tax Credits | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(759)	(788)		(788)
Other Cost of Removal Obligations
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(1,312)	(64)		(64)
Other Cost of Removal Obligations | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		28	0		0
Other Cost of Removal Obligations | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		617	(38)		(38)
Other Cost of Removal Obligations | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(186)	0		0
Other Cost of Removal Obligations | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(1,771)	(26)		(26)
Over Recovered Regulatory Clause Revenues
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(287)	(1,430)		(1,430)
Over Recovered Regulatory Clause Revenues | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(3)	11		11
Over Recovered Regulatory Clause Revenues | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(46)	462		462
Over Recovered Regulatory Clause Revenues | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	(196)		(196)
Over Recovered Regulatory Clause Revenues | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ (238)	(1,707)		(1,707)
Regulatory liability amortization period		5 years
Reliability reserves
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ (179)	(191)		(191)
Reliability reserves | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(143)	(166)		(166)
Reliability reserves | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Reliability reserves | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(36)	(25)		(25)
Reliability reserves | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Storm/Property Damage Reserves
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(120)	(216)		(216)
Storm/Property Damage Reserves | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(76)	(97)		(97)
Storm/Property Damage Reserves | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	(83)		(83)
Storm/Property Damage Reserves | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(44)	(36)		(36)
Storm/Property Damage Reserves | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Customer Refunds
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(19)	(183)		(183)
Customer Refunds | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(15)	(62)		(62)
Regulatory liabilities		15	62		62
Customer Refunds | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(4)	(121)		(121)
Regulatory liabilities			119		119
Customer Refunds | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Customer Refunds | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Fuel Hedging (Realized And Unrealized) gains
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(6)
Fuel Hedging (Realized And Unrealized) gains | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(5)
Fuel Hedging (Realized And Unrealized) gains | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(1)
Fuel Hedging (Realized And Unrealized) gains | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets
Fuel Hedging (Realized And Unrealized) gains | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0
Other Regulatory Liabilities
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		(308)	(239)		(239)
Other Regulatory Liabilities | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ (74)	(40)		(40)
Regulatory liability amortization period		11 years
Other Regulatory Liabilities | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ (18)	(21)		(21)
Regulatory liability amortization period		9 years
Other Regulatory Liabilities | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ (2)	(3)		(3)
Regulatory liability amortization period		4 years
Other Regulatory Liabilities | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ (101)	(93)		(93)
Regulatory liability amortization period		20 years
Excess Deferred Income Tax Liabilities Not Subject to Normalization | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 1
Fuel Hedging (Realized And Unrealized) losses
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets			(83)		(83)
Fuel Hedging (Realized And Unrealized) losses | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets			(38)		(38)
Regulatory liability amortization period		3 years 6 months
Fuel Hedging (Realized And Unrealized) losses | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets			(21)		(21)
Regulatory liability amortization period		3 years
Fuel Hedging (Realized And Unrealized) losses | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets			(24)		(24)
Regulatory liability amortization period		4 years
Fuel Hedging (Realized And Unrealized) losses | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets			0		0
AROs
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 5,733	6,096		6,096
AROs | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 1,936	1,971		1,971
AROs | Alabama Power | Maximum
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		64 years
AROs | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 3,505	3,829		3,829
AROs | Georgia Power | Maximum
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		56 years
AROs | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 247	242		242
AROs | Mississippi Power | Maximum
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		55 years
AROs | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 0	0		0
AROs | Southern Company Gas | Maximum
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		85 years
Retiree Benefit Plans
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 3,011	2,517		2,517
Retiree Benefit Plans | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 815	675		675
Retiree Benefit Plans | Alabama Power | Maximum
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		13 years
Retiree Benefit Plans | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 976	848		848
Retiree Benefit Plans | Georgia Power | Maximum
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		14 years
Retiree Benefit Plans | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 140	113		113
Retiree Benefit Plans | Mississippi Power | Maximum
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		13 years
Retiree Benefit Plans | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 146	114		114
Retiree Benefit Plans | Southern Company Gas | Maximum
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		14 years
Remaining Net Book Value of Retired Assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 1,357	1,543		1,543
Remaining Net Book Value of Retired Assets | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		499	562		562
Remaining Net Book Value of Retired Assets | Alabama Power | Plant Gorgas Units 8, 9, And 10
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		451
Remaining Net Book Value of Retired Assets | Alabama Power | Plant Barry Unit 4
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 39
Remaining Net Book Value of Retired Assets | Alabama Power | Maximum | Plant Gorgas Units 8, 9, And 10
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		14 years
Remaining Net Book Value of Retired Assets | Alabama Power | Maximum | Plant Barry Unit 4
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		11 years
Remaining Net Book Value of Retired Assets | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 841	$ 962		$ 962
Remaining Net Book Value of Retired Assets | Georgia Power | Plant Wansley Units 1 and 2
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		488
Remaining Net Book Value of Retired Assets | Georgia Power | Plant Hammond Units 1 - 4 and Plant Branch Units 2 - 4
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		339
Remaining Net Book Value of Retired Assets | Georgia Power | Plant Branch Unit 4
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 8
Remaining Net Book Value of Retired Assets | Georgia Power | Maximum
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period			3 years		3 years		4 years
Remaining Net Book Value of Retired Assets | Georgia Power | Maximum | Plant Hammond Units 1 - 4 and Plant Branch Units 2 - 4
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		12 years
Remaining Net Book Value of Retired Assets | Georgia Power | Minimum | Plant Hammond Units 1 - 4 and Plant Branch Units 2 - 4
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		1 year
Remaining Net Book Value of Retired Assets | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 17	$ 19		$ 19
Remaining Net Book Value of Retired Assets | Mississippi Power | Plant Watson and Plant Greene County | Retail electric revenues
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		10 years
Remaining Net Book Value of Retired Assets | Mississippi Power | Plant Watson and Plant Greene County | Wholesale electric revenues
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		14 years
Remaining Net Book Value of Retired Assets | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 0	0		0
Deferred Income Tax Charges
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		897	866		866
Deferred Income Tax Charges | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		262	250		250
Deferred Income Tax Charges | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		605	583		583
Deferred Income Tax Charges | Georgia Power | Plant Vogtle Units 3 and 4
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 17
Regulatory asset amortization period		10 years
Regulatory asset		$ 145
Deferred Income Tax Charges | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		28	30		30
Deferred Income Tax Charges | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Under Recovered Regulatory Clause Revenues
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		413	953		953
Under Recovered Regulatory Clause Revenues | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 381	788		788
Under Recovered Regulatory Clause Revenues | Alabama Power | Maximum
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		7 years
Under Recovered Regulatory Clause Revenues | Alabama Power | Minimum
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		1 year
Under Recovered Regulatory Clause Revenues | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 0	0		0
Regulatory asset amortization period		2 years
Under Recovered Regulatory Clause Revenues | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 12	31		31
Under Recovered Regulatory Clause Revenues | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 20	134		134
Regulatory asset amortization period		5 years
Fuel Hedging (Realized And Unrealized) losses
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 270	60		60
Fuel Hedging (Realized And Unrealized) losses | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		100	15		15
Regulatory asset amortization period	5 years
Fuel Hedging (Realized And Unrealized) losses | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		121	45		45
Fuel Hedging (Realized And Unrealized) losses | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		49	0		0
Fuel Hedging (Realized And Unrealized) losses | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Regulatory asset amortization period	2 years
Deferred Depreciation
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		270
Deferred Depreciation | Plant Scherer Units 1 through 3
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 70
Regulatory asset amortization period		6 years
Deferred Depreciation | Plant Bowen Units 1 and 2
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 40
Deferred Depreciation | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		143
Deferred Depreciation | Alabama Power | Plant Barry Unit 5
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		57
Deferred Depreciation | Alabama Power | Plant Barry
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		24
Deferred Depreciation | Alabama Power | Plant Gaston Unit 5
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		62
Deferred Depreciation | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		127
Deferred Depreciation | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0
Deferred Depreciation | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0
Environmental Remediation
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		255	294		294
Environmental Remediation | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Environmental Remediation | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		20	25		25
Environmental Remediation | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Environmental Remediation | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		235	269		269
Loss on Reacquired Debt
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		238	257		257
Loss on Reacquired Debt | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 35	38		38
Loss on Reacquired Debt | Alabama Power | Maximum
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		24 years
Loss on Reacquired Debt | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 197	213		213
Loss on Reacquired Debt | Georgia Power | Maximum
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		29 years
Loss on Reacquired Debt | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 5	5		5
Loss on Reacquired Debt | Mississippi Power | Maximum
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		18 years
Loss on Reacquired Debt | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 1	1		1
Loss on Reacquired Debt | Southern Company Gas | Maximum
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		4 years
Vacation Pay
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 217	212		212
Regulatory asset amortization period		1 year
Vacation Pay | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 83	82		82
Vacation Pay | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		107	108		108
Vacation Pay | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		11	10		10
Vacation Pay | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		16	12		12
Software and Cloud Computing Costs
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 150	111		111
Regulatory asset amortization period		5 years
Software and Cloud Computing Costs | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 59	46		46
Regulatory asset amortization period		10 years
Software and Cloud Computing Costs | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 84	59		59
Software and Cloud Computing Costs | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		2	0		0
Software and Cloud Computing Costs | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 5	6		6
Regulatory asset amortization period		10 years
Regulatory Clauses
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 140	142		142
Regulatory Clauses | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		112	142		142
Regulatory Clauses | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Regulatory Clauses | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Regulatory Clauses | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		28	0		0
Storm Damage
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		92	44		44
Storm Damage | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Storm Damage | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		54	0		0
Storm Damage | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 38	44		44
Regulatory asset amortization period		7 years
Storm Damage | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 0	0		0
Nuclear Outage
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		83	82		82
Nuclear Outage | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 50	52		52
Nuclear Outage | Alabama Power | Plant Farley
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		18 months
Nuclear Outage | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 33	30		30
Nuclear Outage | Georgia Power | Maximum | Plant Hatch (nuclear) Units 1 and 2
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		24 months
Nuclear Outage | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 0	0		0
Nuclear Outage | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Long Term Debt Fair Value Adjustment
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		60	69		69
Long Term Debt Fair Value Adjustment | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Long Term Debt Fair Value Adjustment | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Long Term Debt Fair Value Adjustment | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Long Term Debt Fair Value Adjustment | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 60	69		69
Long Term Debt Fair Value Adjustment | Southern Company Gas | Maximum
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		15 years
Qualifying Repairs Of Natural Gas Distribution Systems
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 40	26		26
Qualifying Repairs Of Natural Gas Distribution Systems | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Qualifying Repairs Of Natural Gas Distribution Systems | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Qualifying Repairs Of Natural Gas Distribution Systems | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Qualifying Repairs Of Natural Gas Distribution Systems | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 40	26		26
Qualifying Repairs Of Natural Gas Distribution Systems | Atlanta Gas Light
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		20 years
Plant Daniel Units 3 and 4
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 25	27		27
Plant Daniel Units 3 and 4 | Retail electric revenues
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		17
Plant Daniel Units 3 and 4 | Wholesale electric revenues
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		8
Plant Daniel Units 3 and 4 | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Plant Daniel Units 3 and 4 | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Plant Daniel Units 3 and 4 | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		25	27		27
Plant Daniel Units 3 and 4 | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Kemper County energy facility assets, net
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		7	20		20
Kemper County energy facility assets, net | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Kemper County energy facility assets, net | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Kemper County energy facility assets, net | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		7	20		20
Regulatory asset		9
Regulatory liabilities		2
Kemper County energy facility assets, net | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		0	0		0
Other Regulatory Assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		182	171		171
Other Regulatory Assets | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 39	36		36
Regulatory asset amortization period		20 years
Other Regulatory Assets | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 33	27		27
Regulatory asset amortization period		10 years
Other Regulatory Assets | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 18	16		16
Regulatory asset amortization period		14 years
Other Regulatory Assets | Southern Company Gas
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 93	$ 92		$ 92
Regulatory asset amortization period		15 years
CCR AROs | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period		38 years
CCR AROs | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory asset amortization period	4 years	3 years
Regulatory Clauses, Amortized Through PEP | Mississippi Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets		$ 12