Summary of Significant Accounting Policies - Regulatory Assets and Liabilities (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended			36 Months Ended
	Jul. 31, 2016	Dec. 31, 2019	Dec. 31, 2016	Dec. 31, 2014	Dec. 31, 2016	Aug. 29, 2016	Dec. 31, 2015
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 5,866		$ 5,866		$ 5,564
Other cost of removal obligations
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			(2,774)		(2,774)		(1,177)
Deferred income tax credits
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			(219)		(219)		(187)
Over recovered regulatory clause revenues
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			(203)		(203)		(261)
Property damage reserves-liability
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			(177)		(177)		(178)
Other regulatory liabilities
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			(110)		(110)		(35)
Asset retirement obligations
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			(10)		(10)		(45)
Retiree Benefit Plans
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			3,959		3,959		3,440
Asset retirement obligations
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			1,080		1,080		481
Other regulatory assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			355		355		299
Loss on reacquired debt
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			243		243		248
Environmental remediation-asset
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			491		491		78
Under recovered regulatory clause revenues
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			273		273		142
Property damage reserves-asset
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			206		206		92
Kemper IGCC
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			201		201		216
Vacation pay
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 182		182		178
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			1 year
Long-term debt fair value adjustment
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 155		155		0
Deferred PPA charges
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			141		141		163
Nuclear outage
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			97		97		88
Fuel-hedging-asset
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			35		35		225
Remaining net book value of retired assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			351		351		283
Deferred Income Tax Charge [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 1,590		1,590		1,514
Maximum [Member]
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Life of new issue			50 years
Power purchase agreement period			7 years
Maximum [Member] | Other regulatory liabilities
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory Liability, Amortization Period			4 years
Maximum [Member] | Retiree Benefit Plans
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			15 years
Maximum [Member] | Other regulatory assets
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			50 years
Maximum [Member] | Asset Group 1 [Member]
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			10 years
Maximum [Member] | Fuel-hedging-asset
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			5 years
Maximum [Member] | Remaining net book value of retired assets
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			11 years
Maximum [Member] | Deferred Income Tax Charge [Member]
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			70 years
Alabama Power [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Fuel Hedging Assets and Liabilities, Amortization Period			3 years 6 months
Total assets (liabilities), net			$ 1,047		1,047		791
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Medicare drug subsidy obligation related to subsidiary			16		16		17
Amortization of regulatory assets				$ 123
Alabama Power [Member] | Other cost of removal obligations
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			(684)		(684)		(722)
Alabama Power [Member] | Deferred income tax credits
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			(65)		(65)		(70)
Alabama Power [Member] | Over recovered regulatory clause revenues
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net							(97)
Alabama Power [Member] | Other regulatory liabilities
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			(23)		(23)		(8)
Alabama Power [Member] | Asset retirement obligations
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net							(40)
Alabama Power [Member] | Natural disaster reserve
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			(69)		(69)		(75)
Alabama Power [Member] | Retiree Benefit Plans
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			947		947		903
Alabama Power [Member] | Asset retirement obligations
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			12		12
Alabama Power [Member] | Other regulatory assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			50		50		53
Alabama Power [Member] | Loss on reacquired debt
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			68		68		75
Alabama Power [Member] | Under recovered regulatory clause revenues
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			76		76
Alabama Power [Member] | Vacation pay
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			69		69		66
Alabama Power [Member] | Nuclear outage
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			70		70		53
Alabama Power [Member] | Fuel-hedging-asset
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			1		1		55
Alabama Power [Member] | Remaining net book value of retired assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 69		69		76
Alabama Power [Member] | Remaining net book value of retired assets
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			11 years
Alabama Power [Member] | Deferred Income Tax Charge [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 526		526		522
Alabama Power [Member] | Maximum [Member]
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Life of new issue			50 years
Alabama Power [Member] | Maximum [Member] | Retiree Benefit Plans
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			15 years
Alabama Power [Member] | Maximum [Member] | Deferred income tax charges
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			15 years
Alabama Power [Member] | Maximum [Member] | Nuclear outage
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			10 years
Alabama Power [Member] | Maximum [Member] | Deferred Income Tax Charge [Member]
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			50 years
Gulf Power [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 320		320		296
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory asset						$ 63
Life of new issue			40 years
Gulf Power [Member] | Over Under Recovered Regulatory Clause Revenues [Member]
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			1 year
Gulf Power [Member] | Deferred Income Tax Charge [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ (2)		(2)		(3)
Gulf Power [Member] | Other cost of removal obligations
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			(278)		(278)		(262)
Gulf Power [Member] | Over recovered regulatory clause revenues
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			(23)		(23)		(22)
Gulf Power [Member] | Property damage reserves-liability
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			(40)		(40)		(38)
Gulf Power [Member] | Asset retirement obligations
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net							(1)
Gulf Power [Member] | Retiree Benefit Plans
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			160		160		147
Gulf Power [Member] | Asset retirement obligations
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			7		7
Gulf Power [Member] | Other regulatory assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			18		18		16
Gulf Power [Member] | Loss on reacquired debt
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			18		18		15
Gulf Power [Member] | Environmental remediation-asset
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 44		44		46
Gulf Power [Member] | Vacation pay
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			1 year
Gulf Power [Member] | Deferred PPA charges
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 141		141		163
Gulf Power [Member] | Ash Pond Closure [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 75		75		29
Gulf Power [Member] | Fuel Hedging Assets and Liabilities [Member]
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			5 years
Gulf Power [Member] | Fuel-hedging-asset
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 24		24		104
Gulf Power [Member] | Remaining net book value of retired assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			66		66		4
Gulf Power [Member] | Regulatory asset, offset to other cost of removal
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			29		29		29
Gulf Power [Member] | Deferred Return On Transmission Upgrades [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			25		25		10
Gulf Power [Member] | Deferred Income Tax Charge [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 56		56		59
Gulf Power [Member] | Maximum [Member] | Retiree Benefit Plans
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			14 years
Gulf Power [Member] | Maximum [Member] | Deferred PPA charges
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			7 years
Gulf Power [Member] | Maximum [Member] | Deferred Income Tax Charge, AROs, Cost Of Removal Obligations, Deferred Income Tax Credits [Member]
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			65 years
Southern Company Gas [Member] | Other regulatory assets
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			12 months
Southern Company Gas [Member] | Vacation pay
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			1 year
Southern Company Gas [Member] | Maximum [Member] | Retiree Benefit Plans
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			11 years
Southern Company Gas [Member] | Maximum [Member] | Other regulatory assets
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			10 years
Southern Company Gas [Member] | Maximum [Member] | Long-term debt fair value adjustment
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			22 years
Southern Company Gas [Member] | Maximum [Member] | Financial Instrument Hedging [Member]
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			2 years
Southern Company Gas [Member] | Maximum [Member] | Other regulatory liabilities
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			4 years
Southern Company Gas [Member] | Maximum [Member] | Deferred Income Tax Charges and Other Cost of Removal Obligations [Member]
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			30 years
Southern Company Gas [Member] | Successor [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ (715)		(715)
Southern Company Gas [Member] | Successor [Member] | Deferred Income Tax Charge [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			(22)		(22)
Southern Company Gas [Member] | Successor [Member] | Other cost of removal obligations
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			(1,616)		(1,616)
Southern Company Gas [Member] | Successor [Member] | Financial Instrument Hedging [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			(21)		(21)
Southern Company Gas [Member] | Successor [Member] | Over recovered regulatory clause revenues
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			(104)		(104)
Southern Company Gas [Member] | Successor [Member] | Other regulatory liabilities
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			(18)		(18)
Southern Company Gas [Member] | Successor [Member] | Retiree Benefit Plans
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			325		325
Southern Company Gas [Member] | Successor [Member] | Other regulatory assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			58		58
Southern Company Gas [Member] | Successor [Member] | Under recovered regulatory clause revenues
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			118		118
Southern Company Gas [Member] | Successor [Member] | Long-term debt fair value adjustment
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			154		154
Southern Company Gas [Member] | Successor [Member] | Environmental Remediation [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			411		411
Southern Company Gas [Member] | Successor [Member] | Financial Instrument Hedging [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 0		0
Southern Company Gas [Member] | Predecessor [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net							(987)
Southern Company Gas [Member] | Predecessor [Member] | Deferred Income Tax Charge [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net							(27)
Southern Company Gas [Member] | Predecessor [Member] | Other cost of removal obligations
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net							(1,591)
Southern Company Gas [Member] | Predecessor [Member] | Financial Instrument Hedging [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net							0
Southern Company Gas [Member] | Predecessor [Member] | Over recovered regulatory clause revenues
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net							(87)
Southern Company Gas [Member] | Predecessor [Member] | Other regulatory liabilities
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net							(20)
Southern Company Gas [Member] | Predecessor [Member] | Retiree Benefit Plans
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net							125
Southern Company Gas [Member] | Predecessor [Member] | Other regulatory assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net							47
Southern Company Gas [Member] | Predecessor [Member] | Under recovered regulatory clause revenues
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net							69
Southern Company Gas [Member] | Predecessor [Member] | Long-term debt fair value adjustment
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net							66
Southern Company Gas [Member] | Predecessor [Member] | Environmental Remediation [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net							401
Southern Company Gas [Member] | Predecessor [Member] | Financial Instrument Hedging [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net							30
Southern Company Gas [Member] | Predecessor [Member] | Over Under Recovered Regulatory Clause Revenues [Member]
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			9 years
Mississippi Power [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 737		737		667
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period	5 years
Mississippi Power [Member] | Other cost of removal obligations
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			(170)		(170)		(167)
Mississippi Power [Member] | Property damage reserves-liability
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			(68)		(68)		(64)
Mississippi Power [Member] | Other regulatory liabilities
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			(16)		(16)		(11)
Mississippi Power [Member] | Kemper IGCC [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			201		201		216
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory asset			$ 97		97
Mississippi Power [Member] | Retiree Benefit Plans
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			14 years
Mississippi Power [Member] | Asset retirement obligations
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 83		83		70
Mississippi Power [Member] | Other regulatory assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 42		42		27
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			50 years
Mississippi Power [Member] | Fuel Hedging Assets and Liabilities [Member]
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			3 years
Mississippi Power [Member] | Fuel-hedging-asset
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 7		7		50
Mississippi Power [Member] | Remaining net book value of retired assets
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			1 year
Mississippi Power [Member] | Remaining net book value of retired assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 53		53		36
Mississippi Power [Member] | Property Tax [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 37		37		27
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			12 months
Mississippi Power [Member] | Deferred Income Tax Charge [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 362		362		291
Mississippi Power [Member] | Retiree Benefit Plans - Regulatory Assets [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 173		173		163
Mississippi Power [Member] | Plant Daniel Units 3 and 4
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			10 years
Mississippi Power [Member] | Plant Daniel Units 3 and 4 | Plant Daniel Units 3 and 4
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 33		33		29
Mississippi Power [Member] | Amortization Period One | Fuel Hedging Assets and Liabilities [Member]
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			2 years
Mississippi Power [Member] | Amortization Period Two | Fuel Hedging Assets and Liabilities [Member]
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			7 years
Mississippi Power [Member] | Amortization Period Three | Fuel Hedging Assets and Liabilities [Member]
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			10 years
Georgia Power [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 3,506		3,506		2,933
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Refueling cycles maximum period			24 months
Georgia Power [Member] | Other cost of removal obligations
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 3		3		(31)
Georgia Power [Member] | Deferred income tax credits
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			(121)		(121)		(105)
Georgia Power [Member] | Other regulatory liabilities
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			(39)		(39)		(2)
Georgia Power [Member] | Retiree Benefit Plans
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 1,348		1,348		1,307
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			13 years
Georgia Power [Member] | Deferred income tax charges
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 26		26
Georgia Power [Member] | Asset retirement obligations
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			893		893		411
Georgia Power [Member] | Other regulatory assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 97		97		110
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			24 months
Amortization of regulatory assets			$ 46
Georgia Power [Member] | Loss on reacquired debt
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			137		137		150
Georgia Power [Member] | Vacation pay
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 91		91		91
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			1 year
Georgia Power [Member] | Canceled Construction Projects [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 44		44		56
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			9 years
Georgia Power [Member] | Remaining net book value of retired assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			$ 166		166		171
Georgia Power [Member] | Obsolete Inventories of Retired Units [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			31		31
Georgia Power [Member] | Storm damage reserves
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			206		206		92
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Amortization of regulatory assets					185
Georgia Power [Member] | Deferred Income Tax Charge [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Total assets (liabilities), net			681		681		$ 683
Georgia Power [Member] | Plant Mitchell Unit 3 [Member]
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Net Book Value Of Planned Units Retirements			$ 12		$ 12
Georgia Power [Member] | Maximum [Member]
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Life of new issue			36 years
Georgia Power [Member] | Maximum [Member] | Deferred Income Tax Charge, AROs, Cost Of Removal Obligations, Deferred Income Tax Credits [Member]
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			70 years
Georgia Power [Member] | Maximum [Member] | Remaining net book value of retired assets
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			10 years
Georgia Power [Member] | Scenario, Forecast [Member] | Remaining net book value of retired assets
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Amortization of regulatory assets		$ 5
Deferred Income Tax Charge, AROs, Cost Of Removal Obligations, Deferred Income Tax Credits [Member] | Mississippi Power [Member]
Schedule of Regulatory Assets and Liabilities - Other Information [Abstract]
Regulatory amortization period			49 years