Georgia Power (GPJA) 10-Q 1 Nov 23 2023 Q3 Quarterly report Financial data

Cover Page

Cover Page	9 Months Ended
	Sep. 30, 2023 shares
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
Document Transition Report	false
Entity File Number	1-3526
Entity Registrant Name	The Southern Company
Entity Tax Identification Number	58-0690070
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	30 Ivan Allen Jr. Boulevard, N.W.
Entity Address, City or Town	Atlanta
Entity Address, State or Province	GA
Entity Address, Postal Zip Code	30308
City Area Code	404
Local Phone Number	506-5000
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)	1,090,619,349
Entity Central Index Key	0000092122
Amendment Flag	false
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Common Stock, par value $5 per share
Document Information [Line Items]
Title of 12(b) Security	Common Stock, par value $5 per share
Trading Symbol	SO
Security Exchange Name	NYSE
Series 2017B 5.25% Junior Subordinated Notes due 2077
Document Information [Line Items]
Title of 12(b) Security	Series 2017B 5.25% Junior Subordinated Notes due 2077
Trading Symbol	SOJC
Security Exchange Name	NYSE
Series 2020A 4.95% Junior Subordinated Notes due 2080
Document Information [Line Items]
Title of 12(b) Security	Series 2020A 4.95% Junior Subordinated Notes due 2080
Trading Symbol	SOJD
Security Exchange Name	NYSE
Series 2020C 4.20% Junior Subordinated Notes due 2060
Document Information [Line Items]
Title of 12(b) Security	Series 2020C 4.20% Junior Subordinated Notes due 2060
Trading Symbol	SOJE
Security Exchange Name	NYSE
Series 2021B 1.875% Fixed-to-Fixed Reset Rate Junior Subordinated Notes due 2081
Document Information [Line Items]
Title of 12(b) Security	Series 2021B 1.875% Fixed-to-Fixed Reset Rate Junior Subordinated Notes due 2081
Trading Symbol	SO 81
Security Exchange Name	NYSE
ALABAMA POWER CO
Document Information [Line Items]
Entity File Number	1-3164
Entity Registrant Name	Alabama Power Company
Entity Tax Identification Number	63-0004250
Entity Incorporation, State or Country Code	AL
Entity Address, Address Line One	600 North 18th Street
Entity Address, City or Town	Birmingham
Entity Address, State or Province	AL
Entity Address, Postal Zip Code	35203
City Area Code	205
Local Phone Number	257-1000
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)	30,537,500
Entity Central Index Key	0000003153
GEORGIA POWER CO
Document Information [Line Items]
Entity File Number	1-6468
Entity Registrant Name	Georgia Power Company
Entity Tax Identification Number	58-0257110
Entity Incorporation, State or Country Code	GA
Entity Address, Address Line One	241 Ralph McGill Boulevard, N.E.
Entity Address, City or Town	Atlanta
Entity Address, State or Province	GA
Entity Address, Postal Zip Code	30308
City Area Code	404
Local Phone Number	506-6526
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)	9,261,500
Entity Central Index Key	0000041091
GEORGIA POWER CO | Series 2017A 5.00% Junior Subordinated Notes due 2077
Document Information [Line Items]
Title of 12(b) Security	Series 2017A 5.00% Junior Subordinated Notes due 2077
Trading Symbol	GPJA
Security Exchange Name	NYSE
MISSISSIPPI POWER CO
Document Information [Line Items]
Entity File Number	001-11229
Entity Registrant Name	Mississippi Power Company
Entity Tax Identification Number	64-0205820
Entity Incorporation, State or Country Code	MS
Entity Address, Address Line One	2992 West Beach Boulevard
Entity Address, City or Town	Gulfport
Entity Address, State or Province	MS
Entity Address, Postal Zip Code	39501
City Area Code	228
Local Phone Number	864-1211
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)	1,121,000
Entity Central Index Key	0000066904
SOUTHERN POWER CO
Document Information [Line Items]
Entity File Number	001-37803
Entity Registrant Name	Southern Power Company
Entity Tax Identification Number	58-2598670
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	30 Ivan Allen Jr. Boulevard, N.W.
Entity Address, City or Town	Atlanta
Entity Address, State or Province	GA
Entity Address, Postal Zip Code	30308
City Area Code	404
Local Phone Number	506-5000
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)	1,000
Entity Central Index Key	0001160661
SOUTHERN POWER CO | Series 2016B 1.850% Senior Notes due 2026
Document Information [Line Items]
Title of 12(b) Security	Series 2016B 1.850% Senior Notes due 2026
Trading Symbol	SO/26A
Security Exchange Name	NYSE
SOUTHERN Co GAS
Document Information [Line Items]
Entity File Number	1-14174
Entity Registrant Name	Southern Company Gas
Entity Tax Identification Number	58-2210952
Entity Incorporation, State or Country Code	GA
Entity Address, Address Line One	Ten Peachtree Place, N.E.
Entity Address, City or Town	Atlanta
Entity Address, State or Province	GA
Entity Address, Postal Zip Code	30309
City Area Code	404
Local Phone Number	584-4000
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)	100
Entity Central Index Key	0001004155

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income (Unaudited) - Southern - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Operating Revenues:
Total operating revenues	$ 6,980	$ 8,378	$ 19,208	$ 22,232
Operating Expenses:
Other operations and maintenance	1,424	1,527	4,352	4,568
Depreciation and amortization	1,143	922	3,365	2,728
Taxes other than income taxes	341	352	1,076	1,073
Estimated loss on Plant Vogtle Units 3 and 4	160	(70)	160	(18)
Total operating expenses	4,870	6,185	14,589	17,000
Operating Income	2,110	2,193	4,619	5,232
Other Income and (Expense):
Allowance for equity funds used during construction	66	59	200	163
Earnings from equity method investments	32	28	110	109
Interest expense, net of amounts capitalized	(620)	(511)	(1,812)	(1,461)
Other income (expense), net	141	132	428	414
Total other income and (expense)	(381)	(292)	(1,074)	(775)
Earnings Before Income Taxes	1,729	1,901	3,545	4,457
Income taxes	297	414	492	891
Net Income	1,432	1,487	3,053	3,566
Dividends on preferred stock of subsidiaries	0	3	0	10
Net income (loss) attributable to noncontrolling interests	10	12	(68)	(55)
Net Income	$ 1,422	$ 1,472	$ 3,121	$ 3,611
Earnings per share -
Basic (in dollars per share)	$ 1.30	$ 1.36	$ 2.86	$ 3.38
Diluted (in dollars per share)	$ 1.29	$ 1.35	$ 2.84	$ 3.36
Average number of shares of common stock outstanding — (in millions)
Basic (in shares)	1,092	1,082	1,092	1,070
Diluted (in shares)	1,099	1,088	1,098	1,076
Retail electric revenues
Operating Revenues:
Total operating revenues	$ 5,139	$ 5,961	$ 12,597	$ 14,363
Wholesale electric revenues
Operating Revenues:
Total operating revenues	727	1,197	1,930	2,798
Other electric revenues
Operating Revenues:
Total operating revenues	203	185	602	554
Natural Gas
Operating Revenues:
Total operating revenues	689	857	3,417	3,998
Other revenues
Operating Revenues:
Total operating revenues	222	178	662	519
Operating Expenses:
Total cost of sales	126	92	381	275
Fuel
Operating Expenses:
Total cost of sales	1,367	2,423	3,376	5,249
Purchased power
Operating Expenses:
Total cost of sales	207	645	680	1,285
Natural gas
Operating Expenses:
Total cost of sales	$ 102	$ 294	$ 1,199	$ 1,840

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Income (Unaudited) - Southern (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Total operating revenues	$ 6,980	$ 8,378	$ 19,208	$ 22,232
Alternative revenue programs
Total operating revenues	$ 0	$ (1)	$ 11	$ 0

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - Southern - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Statement of Comprehensive Income [Abstract]
Consolidated Net Income	$ 1,432	$ 1,487	$ 3,053	$ 3,566
Qualifying hedges:
Changes in fair value, net of tax	2	0	(34)	(27)
Reclassification adjustment for amounts included in net income, net of tax	36	26	70	100
Pension and other postretirement benefit plans:
Reclassification adjustment for amounts included in net income, net of tax	0	2	1	8
Total other comprehensive income	38	28	37	81
Comprehensive Income	1,470	1,515	3,090	3,647
Dividends on preferred stock of subsidiaries	0	3	0	10
Comprehensive income (loss) attributable to noncontrolling interests	10	12	(68)	(55)
Comprehensive Income	$ 1,460	$ 1,500	$ 3,158	$ 3,692

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - Southern (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Statement of Comprehensive Income [Abstract]
Changes in fair value, tax	$ 3	$ 2	$ (11)	$ (5)
Qualifying hedges, reclassification adjustment, tax	12	8	25	32
Reclassification adjustment for amounts included in net income, tax	$ 0	$ 1	$ 0	$ 3

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Cash Flows (Unaudited) - Southern - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Operating Activities:
Consolidated net income	$ 3,053	$ 3,566
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	3,699	3,084
Deferred income taxes	(52)	608
Utilization of federal investment tax credits	195	266
Allowance for equity funds used during construction	(200)	(163)
Pension, postretirement, and other employee benefits	(397)	(322)
Settlement of asset retirement obligations	(444)	(314)
Stock based compensation expense	119	116
Estimated loss on Plant Vogtle Units 3 and 4	160	(18)
Storm damage accruals	41	160
Natural gas cost under recovery – long-term	0	207
Retail fuel cost under recovery – long-term	(157)	(1,701)
Other, net	(67)	(119)
Changes in certain current assets and liabilities —
Receivables	524	(316)
Retail fuel cost under recovery	513	(104)
Fossil fuel stock	(254)	(76)
Materials and supplies	(271)	(138)
Natural gas cost under recovery	108	(124)
Other current assets	(32)	(310)
Accounts payable	(1,031)	805
Accrued taxes	376	167
Accrued compensation	(197)	(123)
Customer refunds	(177)	(52)
Natural gas cost over recovery	165	0
Other current liabilities	66	(82)
Net cash provided from operating activities	5,740	5,017
Investing Activities:
Property additions	(6,561)	(5,502)
Nuclear decommissioning trust fund purchases	(885)	(858)
Nuclear decommissioning trust fund sales	879	854
Proceeds from dispositions	165	120
Cost of removal, net of salvage	(421)	(518)
Construction payables	241	15
Other investing activities	(139)	(63)
Net cash used for investing activities	(6,721)	(5,952)
Financing Activities:
Increase (decrease) in notes payable, net	(298)	(349)
Proceeds —
Long-term debt	7,812	3,800
Short-term borrowings	250	1,200
Common stock	26	1,803
Redemptions and repurchases —
Long-term debt	(3,567)	(1,932)
Short-term borrowings	(850)	(900)
Capital contributions from noncontrolling interests	21	73
Distributions to noncontrolling interests	(148)	(175)
Payment of common stock dividends	(2,271)	(2,166)
Other financing activities	(141)	(235)
Net cash provided from financing activities	834	1,119
Net Change in Cash, Cash Equivalents, and Restricted Cash	(147)	184
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	2,037	1,829
Cash, Cash Equivalents, and Restricted Cash at End of Period	1,890	2,013
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	1,694	1,425
Income taxes, net	11	160
Noncash transactions —
Accrued property additions at end of period	1,224	872
Right-of-use assets obtained under operating leases	76	27
Right-of-use assets obtained under finance leases	3	114
Reassessment of right-of-use assets under operating leases	$ 0	$ 40

Condensed Consolidated Statem_6

Condensed Consolidated Statements of Cash Flows (Unaudited) - Southern (Parenthetical) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Statement of Cash Flows [Abstract]
Net cash paid for capitalized interest	$ 97	$ 74

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - Southern - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Current Assets:
Cash and cash equivalents	$ 1,676	$ 1,917
Receivables —
Customer accounts	2,230	2,128
Unbilled revenues	547	1,012
Under recovered fuel clause revenues	757	10
Other accounts and notes	553	637
Accumulated provision for uncollectible accounts	(78)	(71)
Materials and supplies	1,913	1,664
Fossil fuel for generation	829	575
Natural gas for sale	406	438
Prepaid expenses	321	347
Assets from risk management activities, net of collateral	36	115
Regulatory assets – asset retirement obligations	358	332
Other regulatory assets	996	968
Other current assets	544	344
Total current assets	11,088	10,416
Property, Plant, and Equipment:
In service	125,573	117,529
Less: Accumulated depreciation	37,199	35,297
Plant in service, net of depreciation	88,374	82,232
Other utility plant, net	522	599
Nuclear fuel, at amortized cost	862	843
Construction work in progress	8,496	10,896
Total property, plant, and equipment	98,254	94,570
Other Property and Investments:
Goodwill	5,161	5,161
Nuclear decommissioning trusts, at fair value	2,207	2,145
Equity investments in unconsolidated subsidiaries	1,376	1,443
Other intangible assets, net of amortization	377	406
Miscellaneous property and investments	651	602
Total other property and investments	9,772	9,757
Deferred Charges and Other Assets:
Operating lease right-of-use assets, net of amortization	1,467	1,531
Deferred charges related to income taxes	889	866
Prepaid pension costs	2,574	2,290
Unamortized loss on reacquired debt	224	238
Deferred under recovered fuel clause revenues	1,279	2,056
Regulatory assets – asset retirement obligations, deferred	5,629	5,764
Other regulatory assets, deferred	5,666	5,918
Other deferred charges and assets	1,479	1,485
Total deferred charges and other assets	19,207	20,148
Total Assets	138,321	134,891
Current Liabilities:
Securities due within one year	3,076	4,285
Notes payable	1,726	2,609
Accounts payable	2,942	3,525
Customer deposits	511	502
Accrued taxes —
Accrued income taxes	177	60
Other accrued taxes	862	764
Accrued interest	573	614
Accrued compensation	936	1,127
Asset retirement obligations	727	694
Liabilities from risk management activities, net of collateral	232	178
Operating lease obligations	181	197
Natural gas cost over recovery	165	0
Other regulatory liabilities	163	382
Other current liabilities	943	787
Total current liabilities	13,214	15,724
Long-term Debt	56,003	50,656
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	10,774	10,036
Deferred credits related to income taxes	4,813	5,235
Accumulated deferred ITCs	2,071	2,133
Employee benefit obligations	1,184	1,238
Operating lease obligations, deferred	1,320	1,388
Asset retirement obligations, deferred	9,872	10,146
Other cost of removal obligations	1,940	1,903
Other regulatory liabilities, deferred	660	733
Other deferred credits and liabilities	1,166	1,167
Total deferred credits and other liabilities	33,800	33,979
Total Liabilities	103,017	100,359
Total Stockholders' Equity	35,304	34,532
Total Liabilities and Stockholders' Equity	$ 138,321	$ 134,891

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) - Southern (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Other intangible assets, amortization	$ 367	$ 340

Condensed Consolidated Statem_7

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - Southern - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Treasury	Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests
Beginning balance (in shares) at Dec. 31, 2021		1,061
Beginning balance (in shares) at Dec. 31, 2021			(1)
Beginning balance at Dec. 31, 2021	$ 32,276	$ 5,279	$ (47)	$ 11,950	$ 10,929	$ (237)	$ 4,402
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated net income (loss)	987				1,032		(45)
Other comprehensive income	42					42
Stock issued (in shares)		3
Stock issued	38	$ 7		31
Stock-based compensation	6			6
Cash dividends on common stock	(702)				(702)
Capital contributions from noncontrolling interests	73						73
Distributions to noncontrolling interests	(98)						(98)
Other	7		$ (2)	7	2
Ending balance (in shares) at Mar. 31, 2022		1,064
Ending balance (in shares) at Mar. 31, 2022			(1)
Ending balance at Mar. 31, 2022	32,629	$ 5,286	$ (49)	11,994	11,261	(195)	4,332
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated net income (loss)	1,085				1,107		(22)
Other comprehensive income	11					11
Stock issued	23	$ 2		21
Stock-based compensation	14			14
Cash dividends on common stock	(723)				(723)
Distributions to noncontrolling interests	(28)						(28)
Other	2		$ (2)	4
Ending balance (in shares) at Jun. 30, 2022		1,064
Ending balance (in shares) at Jun. 30, 2022			(1)
Ending balance at Jun. 30, 2022	33,013	$ 5,288	$ (51)	12,033	11,645	(184)	4,282
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated net income (loss)	1,484				1,472		12
Other comprehensive income	28					28
Stock issued (in shares)		26
Stock issued	1,742	$ 129		1,613
Stock-based compensation	15			15
Cash dividends on common stock	(741)				(741)
Distributions to noncontrolling interests	(57)						(57)
Other	(8)		$ (1)	(4)	(2)	(1)
Ending balance (in shares) at Sep. 30, 2022		1,090
Ending balance (in shares) at Sep. 30, 2022			(1)
Ending balance at Sep. 30, 2022	35,476	$ 5,417	$ (52)	13,657	12,374	(157)	4,237
Beginning balance (in shares) at Dec. 31, 2022		1,090
Beginning balance (in shares) at Dec. 31, 2022			(1)
Beginning balance at Dec. 31, 2022	34,532	$ 5,417	$ (53)	13,673	11,538	(167)	4,124
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated net income (loss)	799				862		(63)
Other comprehensive income	(44)					(44)
Stock issued (in shares)		2
Stock issued	15	$ 4		11
Stock-based compensation	29			29
Cash dividends on common stock	(742)				(742)
Capital contributions from noncontrolling interests	21						21
Distributions to noncontrolling interests	(48)						(48)
Other	0		$ (2)	2
Ending balance (in shares) at Mar. 31, 2023		1,092
Ending balance (in shares) at Mar. 31, 2023			(1)
Ending balance at Mar. 31, 2023	34,562	$ 5,421	$ (55)	13,715	11,658	(211)	4,034
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated net income (loss)	823				838		(15)
Other comprehensive income	43					43
Stock issued	7	$ 1		6
Stock-based compensation	19			19
Cash dividends on common stock	(764)				(764)
Distributions to noncontrolling interests	(42)						(42)
Other	0		$ (1)	2			(1)
Ending balance (in shares) at Jun. 30, 2023		1,092
Ending balance (in shares) at Jun. 30, 2023			(1)
Ending balance at Jun. 30, 2023	34,648	$ 5,422	$ (56)	13,742	11,732	(168)	3,976
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated net income (loss)	1,432				1,422		10
Other comprehensive income	38					38
Stock issued	4			4
Stock-based compensation	7			7
Cash dividends on common stock	(765)				(765)
Distributions to noncontrolling interests	(59)						(59)
Other	(1)		$ (1)	(2)	2
Ending balance (in shares) at Sep. 30, 2023		1,092
Ending balance (in shares) at Sep. 30, 2023			(1)
Ending balance at Sep. 30, 2023	$ 35,304	$ 5,422	$ (57)	$ 13,751	$ 12,391	$ (130)	$ 3,927

Condensed Consolidated Statem_8

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - Southern (Parenthetical) - $ / shares	3 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022
Statement of Stockholders' Equity [Abstract]
Cash dividends (in dollars per share)	$ 0.70	$ 0.70	$ 0.68	$ 0.68	$ 0.68	$ 0.66

Condensed Statements of Income

Condensed Statements of Income (Unaudited) - APC - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Operating Revenues:
Total operating revenues	$ 6,980	$ 8,378	$ 19,208	$ 22,232
Operating Expenses:
Other operations and maintenance	1,424	1,527	4,352	4,568
Depreciation and amortization	1,143	922	3,365	2,728
Taxes other than income taxes	341	352	1,076	1,073
Total operating expenses	4,870	6,185	14,589	17,000
Operating Income	2,110	2,193	4,619	5,232
Other Income and (Expense):
Allowance for equity funds used during construction	66	59	200	163
Interest expense, net of amounts capitalized	(620)	(511)	(1,812)	(1,461)
Total other income (expense), net	141	132	428	414
Total other income and (expense)	(381)	(292)	(1,074)	(775)
Earnings Before Income Taxes	1,729	1,901	3,545	4,457
Income taxes	297	414	492	891
Consolidated Net Income	1,432	1,487	3,053	3,566
Dividends on preferred stock of subsidiaries	0	3	0	10
Net Income	1,422	1,472	3,121	3,611
Retail electric revenues
Operating Revenues:
Total operating revenues	5,139	5,961	12,597	14,363
Wholesale electric revenues
Operating Revenues:
Total operating revenues	727	1,197	1,930	2,798
Other electric revenues
Operating Revenues:
Total operating revenues	203	185	602	554
Natural Gas
Operating Revenues:
Total operating revenues	689	857	3,417	3,998
Other revenues
Operating Revenues:
Total operating revenues	222	178	662	519
Operating Expenses:
Total cost of sales	126	92	381	275
Fuel
Operating Expenses:
Total cost of sales	1,367	2,423	3,376	5,249
Purchased power
Operating Expenses:
Total cost of sales	207	645	680	1,285
Alabama Power
Operating Revenues:
Total operating revenues	2,083	2,444	5,420	6,023
Operating Expenses:
Other operations and maintenance	411	418	1,275	1,270
Depreciation and amortization	351	220	1,045	652
Taxes other than income taxes	110	106	333	309
Total operating expenses	1,396	1,708	4,056	4,237
Operating Income	687	736	1,364	1,786
Other Income and (Expense):
Allowance for equity funds used during construction	23	18	65	51
Interest expense, net of amounts capitalized	(104)	(98)	(311)	(278)
Total other income (expense), net	38	38	117	101
Total other income and (expense)	(43)	(42)	(129)	(126)
Earnings Before Income Taxes	644	694	1,235	1,660
Income taxes	79	166	103	394
Consolidated Net Income	565	528	1,132	1,266
Dividends on preferred stock of subsidiaries	0	3	0	10
Net Income	565	525	1,132	1,256
Alabama Power | Retail electric revenues
Operating Revenues:
Total operating revenues	1,860	2,008	4,708	5,015
Alabama Power | Wholesale revenues, non-affiliates
Operating Revenues:
Total operating revenues	106	250	358	522
Alabama Power | Wholesale revenues, affiliates
Operating Revenues:
Total operating revenues	14	70	43	170
Alabama Power | Other revenues
Operating Revenues:
Total operating revenues	103	116	311	316
Alabama Power | Fuel
Operating Expenses:
Total cost of sales	402	666	1,013	1,399
Alabama Power | Purchased power
Operating Expenses:
Total cost of sales	42	185	197	347
Alabama Power | Purchased power, affiliates
Operating Expenses:
Total cost of sales	$ 80	$ 113	$ 193	$ 260

Condensed Statements of Compreh

Condensed Statements of Comprehensive Income (Unaudited) - APC - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Consolidated Net Income	$ 1,432	$ 1,487	$ 3,053	$ 3,566
Qualifying hedges:
Changes in fair value, net of tax	2	0	(34)	(27)
Reclassification adjustment for amounts included in net income, net of tax	36	26	70	100
Total other comprehensive income	38	28	37	81
Comprehensive Income	1,470	1,515	3,090	3,647
Alabama Power
Consolidated Net Income	565	528	1,132	1,266
Qualifying hedges:
Changes in fair value, net of tax	0	1	1	(1)
Reclassification adjustment for amounts included in net income, net of tax	1	1	1	3
Total other comprehensive income	1	2	2	2
Comprehensive Income	$ 566	$ 530	$ 1,134	$ 1,268

Condensed Statements of Compr_2

Condensed Statements of Comprehensive Income (Unaudited) - APC (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Changes in fair value, tax	$ 3	$ 2	$ (11)	$ (5)
Qualifying hedges, reclassification adjustment, tax	12	8	25	32
Alabama Power
Changes in fair value, tax	0	0	0	0
Qualifying hedges, reclassification adjustment, tax	$ 0	$ 0	$ 0	$ 1

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows (Unaudited) - APC - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Operating Activities:
Consolidated net income	$ 3,053	$ 3,566
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	3,699	3,084
Deferred income taxes	(52)	608
Pension, postretirement, and other employee benefits	(397)	(322)
Settlement of asset retirement obligations	(444)	(314)
Retail fuel cost under recovery – long-term	(157)	(1,701)
Other, net	(67)	(119)
Changes in certain current assets and liabilities —
Receivables	524	(316)
Fossil fuel stock	(254)	(76)
Retail fuel cost under recovery	513	(104)
Other current assets	(32)	(310)
Accounts payable	(1,031)	805
Accrued taxes	376	167
Accrued compensation	(197)	(123)
Other current liabilities	66	(82)
Net cash provided from operating activities	5,740	5,017
Investing Activities:
Property additions	(6,561)	(5,502)
Nuclear decommissioning trust fund purchases	(885)	(858)
Nuclear decommissioning trust fund sales	879	854
Cost of removal, net of salvage	(421)	(518)
Change in construction payables, net	241	15
Other investing activities	(139)	(63)
Net cash used for investing activities	(6,721)	(5,952)
Financing Activities:
Payment of common stock dividends	(2,271)	(2,166)
Other financing activities	(141)	(235)
Net cash provided from financing activities	834	1,119
Net Change in Cash, Cash Equivalents, and Restricted Cash	(147)	184
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	2,037	1,829
Cash, Cash Equivalents, and Restricted Cash at End of Period	1,890	2,013
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	1,694	1,425
Income taxes, net	11	160
Noncash transactions —
Accrued property additions at end of period	1,224	872
Right-of-use assets obtained under finance leases	3	114
Alabama Power
Operating Activities:
Consolidated net income	1,132	1,266
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	1,158	817
Deferred income taxes	(210)	210
Pension, postretirement, and other employee benefits	(148)	(85)
Settlement of asset retirement obligations	(188)	(139)
Retail fuel cost under recovery – long-term	0	(413)
Other, net	(21)	(98)
Changes in certain current assets and liabilities —
Receivables	(108)	(296)
Fossil fuel stock	(113)	(40)
Retail fuel cost under recovery	334	(93)
Other current assets	(124)	(75)
Accounts payable	(358)	(22)
Accrued taxes	271	110
Other current liabilities	(103)	(70)
Net cash provided from operating activities	1,522	1,072
Investing Activities:
Property additions	(1,377)	(1,483)
Nuclear decommissioning trust fund purchases	(226)	(273)
Nuclear decommissioning trust fund sales	226	273
Cost of removal, net of salvage	(128)	(163)
Change in construction payables, net	(68)	36
Other investing activities	27	(31)
Net cash used for investing activities	(1,546)	(1,641)
Financing Activities:
Proceeds — Senior notes	200	1,700
Revenue bonds	326	0
Other long-term debt	28	0
Redemptions — Senior notes	0	(550)
Capital contributions from parent company	380	660
Payment of common stock dividends	(856)	(762)
Other financing activities	(12)	(81)
Net cash provided from financing activities	66	967
Net Change in Cash, Cash Equivalents, and Restricted Cash	42	398
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	687	1,060
Cash, Cash Equivalents, and Restricted Cash at End of Period	729	1,458
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	329	278
Income taxes, net	152	178
Noncash transactions —
Accrued property additions at end of period	114	186
Right-of-use assets obtained under operating leases	28	7
Right-of-use assets obtained under finance leases	$ 3	$ 2

Condensed Statements of Cash _2

Condensed Statements of Cash Flows (Unaudited) - APC (Parenthetical) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Net cash paid for capitalized interest	$ 97	$ 74
Alabama Power
Net cash paid for capitalized interest	$ 21	$ 14

Condensed Balance Sheets (Unaud

Condensed Balance Sheets (Unaudited) - APC - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Current Assets:
Cash and cash equivalents	$ 1,676	$ 1,917
Receivables —
Customer accounts, net and Affiliated	2,230	2,128
Unbilled revenues	547	1,012
Other accounts and notes	553	637
Accumulated provision for uncollectible accounts	(78)	(71)
Fossil fuel stock	829	575
Materials and supplies	1,913	1,664
Prepaid expenses	321	347
Other regulatory assets	996	968
Other current assets	544	344
Total current assets	11,088	10,416
Property, Plant, and Equipment:
In service	125,573	117,529
Less: Accumulated depreciation	37,199	35,297
Plant in service, net of depreciation	88,374	82,232
Other utility plant, net	522	599
Nuclear fuel, at amortized cost	862	843
Construction work in progress	8,496	10,896
Total property, plant, and equipment	98,254	94,570
Other Property and Investments:
Nuclear decommissioning trusts, at fair value	2,207	2,145
Equity investments in unconsolidated subsidiaries	1,376	1,443
Miscellaneous property and investments	651	602
Total other property and investments	9,772	9,757
Deferred Charges and Other Assets:
Operating lease right-of-use assets, net of amortization	1,467	1,531
Deferred charges related to income taxes	889	866
Regulatory assets – asset retirement obligations	5,629	5,764
Other regulatory assets, deferred	5,666	5,918
Other deferred charges and assets	1,479	1,485
Total deferred charges and other assets	19,207	20,148
Total Assets	138,321	134,891
Current Liabilities:
Securities due within one year	3,076	4,285
Accounts payable —
Customer deposits	511	502
Accrued interest	573	614
Accrued compensation	936	1,127
Asset retirement obligations	727	694
Other regulatory liabilities	163	382
Other current liabilities	943	787
Total current liabilities	13,214	15,724
Long-term Debt	56,003	50,656
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	10,774	10,036
Deferred credits related to income taxes	4,813	5,235
Accumulated deferred ITCs	2,071	2,133
Employee benefit obligations	1,184	1,238
Operating lease obligations, deferred	1,320	1,388
Asset retirement obligations, deferred	9,872	10,146
Other regulatory liabilities, deferred	660	733
Other deferred credits and liabilities	1,166	1,167
Total deferred credits and other liabilities	33,800	33,979
Total Liabilities	103,017	100,359
Total Stockholders' Equity	35,304	34,532
Total Liabilities and Stockholders' Equity	138,321	134,891
Alabama Power
Current Assets:
Cash and cash equivalents	621	687
Receivables —
Unbilled revenues	162	174
Other accounts and notes	114	153
Accumulated provision for uncollectible accounts	(16)	(14)
Fossil fuel stock	342	229
Materials and supplies	624	557
Prepaid expenses	72	65
Other regulatory assets	549	474
Other current assets	171	67
Total current assets	3,376	2,924
Property, Plant, and Equipment:
In service	34,313	33,472
Less: Accumulated depreciation	11,042	10,470
Plant in service, net of depreciation	23,271	23,002
Other utility plant, net	522	599
Nuclear fuel, at amortized cost	240	239
Construction work in progress	1,759	1,526
Total property, plant, and equipment	25,792	25,366
Other Property and Investments:
Nuclear decommissioning trusts, at fair value	1,165	1,127
Equity investments in unconsolidated subsidiaries	53	57
Miscellaneous property and investments	156	124
Total other property and investments	1,374	1,308
Deferred Charges and Other Assets:
Operating lease right-of-use assets, net of amortization	88	71
Deferred charges related to income taxes	263	250
Prepaid pension and other postretirement benefit costs	735	657
Regulatory assets – asset retirement obligations	1,881	1,845
Other regulatory assets, deferred	1,706	2,107
Other deferred charges and assets	455	442
Total deferred charges and other assets	5,128	5,372
Total Assets	35,670	34,970
Current Liabilities:
Securities due within one year	522	301
Accounts payable —
Customer deposits	105	106
Accrued taxes	305	57
Accrued interest	84	120
Accrued compensation	193	229
Asset retirement obligations	342	330
Other regulatory liabilities	28	96
Other current liabilities	158	91
Total current liabilities	2,419	2,414
Long-term Debt	10,661	10,329
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	4,082	3,981
Deferred credits related to income taxes	1,626	1,925
Accumulated deferred ITCs	76	81
Employee benefit obligations	146	145
Operating lease obligations, deferred	81	67
Asset retirement obligations, deferred	3,859	3,957
Other regulatory liabilities, deferred	284	315
Other deferred credits and liabilities	85	69
Total deferred credits and other liabilities	10,239	10,540
Total Liabilities	23,319	23,283
Total Stockholders' Equity	12,351	11,687
Total Liabilities and Stockholders' Equity	35,670	34,970
Alabama Power | Nonrelated Party
Receivables —
Customer accounts, net and Affiliated	624	431
Accounts payable —
Affiliated and Other	377	641
Alabama Power | Related Party
Receivables —
Customer accounts, net and Affiliated	113	101
Accounts payable —
Affiliated and Other	$ 305	$ 443

Condensed Statements of Common

Condensed Statements of Common Stockholders' Equity (Unaudited) - APC - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Paid-In Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)	Alabama Power	Alabama Power Common Stock	Alabama Power Paid-In Capital	Alabama Power Retained Earnings (Accumulated Deficit)	Alabama Power Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2021							31
Beginning balance at Dec. 31, 2021	$ 32,276	$ 5,279	$ 11,950	$ 10,929	$ (237)	$ 10,713	$ 1,222	$ 6,056	$ 3,448	$ (13)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income						347			347
Capital contributions from parent company						626		626
Other comprehensive income	42				42
Cash dividends on common stock	(702)			(702)		(254)			(254)
Ending balance (in shares) at Mar. 31, 2022							31
Ending balance at Mar. 31, 2022	32,629	5,286	11,994	11,261	(195)	11,432	$ 1,222	6,682	3,541	(13)
Beginning balance (in shares) at Dec. 31, 2021							31
Beginning balance at Dec. 31, 2021	32,276	5,279	11,950	10,929	(237)	10,713	$ 1,222	6,056	3,448	(13)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	3,611					1,256
Ending balance (in shares) at Sep. 30, 2022							31
Ending balance at Sep. 30, 2022	35,476	5,417	13,657	12,374	(157)	11,874	$ 1,222	6,721	3,941	(10)
Beginning balance (in shares) at Mar. 31, 2022							31
Beginning balance at Mar. 31, 2022	32,629	5,286	11,994	11,261	(195)	11,432	$ 1,222	6,682	3,541	(13)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income						383			383
Capital contributions from parent company						32		32
Other comprehensive income	11				11	1				1
Cash dividends on common stock	(723)			(723)		(254)			(254)
Ending balance (in shares) at Jun. 30, 2022							31
Ending balance at Jun. 30, 2022	33,013	5,288	12,033	11,645	(184)	11,594	$ 1,222	6,714	3,670	(12)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	1,472					525			525
Capital contributions from parent company						7		7
Other comprehensive income	28				28	2				2
Cash dividends on common stock	(741)			(741)		(254)			(254)
Ending balance (in shares) at Sep. 30, 2022							31
Ending balance at Sep. 30, 2022	35,476	5,417	13,657	12,374	(157)	11,874	$ 1,222	6,721	3,941	(10)
Beginning balance (in shares) at Dec. 31, 2022							31
Beginning balance at Dec. 31, 2022	34,532	5,417	13,673	11,538	(167)	11,687	$ 1,222	6,710	3,764	(9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income						255			255
Capital contributions from parent company						330		330
Other comprehensive income	(44)				(44)
Cash dividends on common stock	(742)			(742)		(285)			(285)
Ending balance (in shares) at Mar. 31, 2023							31
Ending balance at Mar. 31, 2023	34,562	5,421	13,715	11,658	(211)	11,987	$ 1,222	7,040	3,734	(9)
Beginning balance (in shares) at Dec. 31, 2022							31
Beginning balance at Dec. 31, 2022	34,532	5,417	13,673	11,538	(167)	11,687	$ 1,222	6,710	3,764	(9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	3,121					1,132
Ending balance (in shares) at Sep. 30, 2023							31
Ending balance at Sep. 30, 2023	35,304	5,422	13,751	12,391	(130)	12,351	$ 1,222	7,097	4,040	(8)
Beginning balance (in shares) at Mar. 31, 2023							31
Beginning balance at Mar. 31, 2023	34,562	5,421	13,715	11,658	(211)	11,987	$ 1,222	7,040	3,734	(9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income						312			312
Capital contributions from parent company						29		29
Other comprehensive income	43				43
Cash dividends on common stock	(764)			(764)		(286)			(286)
Ending balance (in shares) at Jun. 30, 2023							31
Ending balance at Jun. 30, 2023	34,648	5,422	13,742	11,732	(168)	12,042	$ 1,222	7,069	3,760	(9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	1,422					565			565
Capital contributions from parent company						28		28
Other comprehensive income	38				38	1				1
Cash dividends on common stock	(765)			(765)		(285)			(285)
Ending balance (in shares) at Sep. 30, 2023							31
Ending balance at Sep. 30, 2023	$ 35,304	$ 5,422	$ 13,751	$ 12,391	$ (130)	$ 12,351	$ 1,222	$ 7,097	$ 4,040	$ (8)

Condensed Statements of Incom_2

Condensed Statements of Income (Unaudited) - GPC - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Operating Revenues:
Total operating revenues	$ 6,980	$ 8,378	$ 19,208	$ 22,232
Operating Expenses:
Other operations and maintenance	1,424	1,527	4,352	4,568
Depreciation and amortization	1,143	922	3,365	2,728
Taxes other than income taxes	341	352	1,076	1,073
Estimated loss on Plant Vogtle Units 3 and 4	160	(70)	160	(18)
Total operating expenses	4,870	6,185	14,589	17,000
Operating Income	2,110	2,193	4,619	5,232
Other Income and (Expense):
Allowance for equity funds used during construction	66	59	200	163
Interest expense, net of amounts capitalized	(620)	(511)	(1,812)	(1,461)
Other income (expense), net	141	132	428	414
Total other income and (expense)	(381)	(292)	(1,074)	(775)
Earnings Before Income Taxes	1,729	1,901	3,545	4,457
Income taxes	297	414	492	891
Net Income	1,432	1,487	3,053	3,566
Retail electric revenues
Operating Revenues:
Total operating revenues	5,139	5,961	12,597	14,363
Wholesale electric revenues
Operating Revenues:
Total operating revenues	727	1,197	1,930	2,798
Other electric revenues
Operating Revenues:
Total operating revenues	203	185	602	554
Natural Gas
Operating Revenues:
Total operating revenues	689	857	3,417	3,998
Other revenues
Operating Revenues:
Total operating revenues	222	178	662	519
Operating Expenses:
Cost of Goods and Services Sold	126	92	381	275
Fuel
Operating Expenses:
Cost of Goods and Services Sold	1,367	2,423	3,376	5,249
Purchased power
Operating Expenses:
Cost of Goods and Services Sold	207	645	680	1,285
GEORGIA POWER CO
Operating Revenues:
Total operating revenues	3,237	3,889	7,805	9,218
Operating Expenses:
Other operations and maintenance	512	595	1,505	1,686
Depreciation and amortization	429	359	1,248	1,066
Taxes other than income taxes	144	155	406	420
Estimated loss on Plant Vogtle Units 3 and 4	160	(70)	160	(18)
Total operating expenses	2,173	2,755	5,687	6,841
Operating Income	1,064	1,134	2,118	2,377
Other Income and (Expense):
Allowance for equity funds used during construction	37	37	121	102
Interest expense, net of amounts capitalized	(166)	(123)	(472)	(347)
Other income (expense), net	45	36	125	140
Total other income and (expense)	(84)	(50)	(226)	(105)
Earnings Before Income Taxes	980	1,084	1,892	2,272
Income taxes	200	226	345	421
Net Income	780	858	1,547	1,851
GEORGIA POWER CO | Retail electric revenues
Operating Revenues:
Total operating revenues	2,996	3,703	7,142	8,629
GEORGIA POWER CO | Wholesale electric revenues
Operating Revenues:
Total operating revenues	69	56	147	186
GEORGIA POWER CO | Other revenues
Operating Revenues:
Total operating revenues	172	130	516	403
GEORGIA POWER CO | Fuel
Operating Expenses:
Cost of Goods and Services Sold	576	841	1,392	1,887
GEORGIA POWER CO | Purchased power
Operating Expenses:
Cost of Goods and Services Sold	131	304	397	700
GEORGIA POWER CO | Purchased power, affiliates
Operating Expenses:
Cost of Goods and Services Sold	$ 221	$ 571	$ 579	$ 1,100

Condensed Statements of Compr_3

Condensed Statements of Comprehensive Income (Unaudited) - GPC - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Consolidated Net Income	$ 1,432	$ 1,487	$ 3,053	$ 3,566
Qualifying hedges:
Changes in fair value, net of tax	2	0	(34)	(27)
Reclassification adjustment for amounts included in net income, net of tax	36	26	70	100
Total other comprehensive income	38	28	37	81
Comprehensive Income	1,470	1,515	3,090	3,647
GEORGIA POWER CO
Consolidated Net Income	780	858	1,547	1,851
Qualifying hedges:
Changes in fair value, net of tax	0	0	(1)	23
Reclassification adjustment for amounts included in net income, net of tax	1	1	3	4
Total other comprehensive income	1	1	2	27
Comprehensive Income	$ 781	$ 859	$ 1,549	$ 1,878

Condensed Statements of Compr_4

Condensed Statements of Comprehensive Income (Unaudited) - GPC (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Changes in fair value, tax	$ 3	$ 2	$ (11)	$ (5)
Qualifying hedges, reclassification adjustment, tax	12	8	25	32
GEORGIA POWER CO
Changes in fair value, tax	0	0	(1)	8
Qualifying hedges, reclassification adjustment, tax	$ 0	$ 0	$ 1	$ 1

Condensed Statements of Cash _3

Condensed Statements of Cash Flows (Unaudited) - GPC - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Operating Activities:
Consolidated net income	$ 3,053	$ 3,566
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	3,699	3,084
Deferred income taxes	(52)	608
Allowance for equity funds used during construction	(200)	(163)
Pension, postretirement, and other employee benefits	(397)	(322)
Settlement of asset retirement obligations	(444)	(314)
Storm damage accruals	41	160
Retail fuel cost under recovery – long-term	(157)	(1,701)
Estimated loss on Plant Vogtle Units 3 and 4	160	(18)
Other, net	(67)	(119)
Changes in certain current assets and liabilities —
Receivables	524	(316)
Retail fuel cost under recovery	513	(104)
Fossil fuel stock	(254)	(76)
Materials and supplies	(271)	(138)
Other current assets	(32)	(310)
Accounts payable	(1,031)	805
Accrued taxes	376	167
Customer refunds	(177)	(52)
Other current liabilities	66	(82)
Net cash provided from operating activities	5,740	5,017
Investing Activities:
Property additions	(6,561)	(5,502)
Nuclear decommissioning trust fund purchases	(885)	(858)
Nuclear decommissioning trust fund sales	879	854
Cost of removal, net of salvage	(421)	(518)
Proceeds from dispositions	165	120
Other investing activities	(139)	(63)
Net cash used for investing activities	(6,721)	(5,952)
Proceeds —
Short-term borrowings	250	1,200
Redemptions and repurchases —
Short-term borrowings	(850)	(900)
Payment of common stock dividends	(2,271)	(2,166)
Other financing activities	(141)	(235)
Net cash provided from financing activities	834	1,119
Net Change in Cash, Cash Equivalents, and Restricted Cash	(147)	184
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	2,037	1,829
Cash, Cash Equivalents, and Restricted Cash at End of Period	1,890	2,013
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	1,694	1,425
Income taxes, net	11	160
Noncash transactions —
Accrued property additions at end of period	1,224	872
Right-of-use assets obtained under operating leases	76	27
Right-of-use assets obtained under finance leases	3	114
GEORGIA POWER CO
Operating Activities:
Consolidated net income	1,547	1,851
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	1,411	1,211
Deferred income taxes	102	266
Allowance for equity funds used during construction	(121)	(102)
Pension, postretirement, and other employee benefits	(207)	(178)
Settlement of asset retirement obligations	(228)	(149)
Storm damage accruals	24	160
Retail fuel cost under recovery – long-term	(157)	(1,287)
Estimated loss on Plant Vogtle Units 3 and 4	160	(18)
Other, net	(12)	(22)
Changes in certain current assets and liabilities —
Receivables	(311)	(321)
Retail fuel cost under recovery	204	0
Fossil fuel stock	(138)	(23)
Materials and supplies	(135)	(67)
Contract assets	(57)	(51)
Other current assets	16	(72)
Accounts payable	(142)	211
Accrued taxes	118	151
Customer refunds	(121)	1
Other current liabilities	16	(79)
Net cash provided from operating activities	1,969	1,482
Investing Activities:
Property additions	(3,501)	(2,556)
Nuclear decommissioning trust fund purchases	(659)	(585)
Nuclear decommissioning trust fund sales	654	581
Cost of removal, net of salvage	(191)	(250)
Change in construction payables, net of joint owner portion	338	148
Proceeds from dispositions	59	56
Other investing activities	(76)	(47)
Net cash used for investing activities	(3,376)	(2,653)
Financing Activities:
Increase in notes payable, net	50	415
Proceeds —
Proceeds — Senior notes	1,750	1,500
Short-term borrowings	250	650
Revenue bonds	229	0
Redemptions and repurchases —
Redemptions — Senior notes	(800)	(400)
Short-term borrowings	(650)	(250)
FFB loan	(64)	(66)
Revenue bonds	0	(53)
Other long-term debt	0	(125)
Capital contributions from parent company	1,837	813
Payment of common stock dividends	(1,392)	(1,268)
Other financing activities	(27)	(45)
Net cash provided from financing activities	1,183	1,171
Net Change in Cash, Cash Equivalents, and Restricted Cash	(224)	0
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	480	33
Cash, Cash Equivalents, and Restricted Cash at End of Period	256	33
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	439	332
Income taxes, net	74	151
Noncash transactions —
Accrued property additions at end of period	942	609
Right-of-use assets obtained under operating leases	17	7
Right-of-use assets obtained under finance leases	18	112
ALABAMA POWER CO
Operating Activities:
Consolidated net income	1,132	1,266
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	1,158	817
Deferred income taxes	(210)	210
Allowance for equity funds used during construction	(65)	(51)
Pension, postretirement, and other employee benefits	(148)	(85)
Settlement of asset retirement obligations	(188)	(139)
Retail fuel cost under recovery – long-term	0	(413)
Other, net	(21)	(98)
Changes in certain current assets and liabilities —
Receivables	(108)	(296)
Retail fuel cost under recovery	334	(93)
Fossil fuel stock	(113)	(40)
Other current assets	(124)	(75)
Accounts payable	(358)	(22)
Accrued taxes	271	110
Other current liabilities	(103)	(70)
Net cash provided from operating activities	1,522	1,072
Investing Activities:
Property additions	(1,377)	(1,483)
Nuclear decommissioning trust fund purchases	(226)	(273)
Nuclear decommissioning trust fund sales	226	273
Cost of removal, net of salvage	(128)	(163)
Other investing activities	27	(31)
Net cash used for investing activities	(1,546)	(1,641)
Proceeds —
Proceeds — Senior notes	200	1,700
Redemptions and repurchases —
Redemptions — Senior notes	0	(550)
Capital contributions from parent company	380	660
Payment of common stock dividends	(856)	(762)
Other financing activities	(12)	(81)
Net cash provided from financing activities	66	967
Net Change in Cash, Cash Equivalents, and Restricted Cash	42	398
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	687	1,060
Cash, Cash Equivalents, and Restricted Cash at End of Period	729	1,458
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	329	278
Income taxes, net	152	178
Noncash transactions —
Accrued property additions at end of period	114	186
Right-of-use assets obtained under finance leases	$ 3	$ 2

Condensed Statements of Cash _4

Condensed Statements of Cash Flows (Unaudited) - GPC (Parenthetical) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Net cash paid for capitalized interest	$ 97	$ 74
GEORGIA POWER CO
Net cash paid for capitalized interest	$ 63	$ 52

Condensed Balance Sheets (Una_2

Condensed Balance Sheets (Unaudited) - GPC - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Current Assets:
Cash and cash equivalents	$ 1,676	$ 1,917
Receivables —
Customer accounts, net and Affiliated	2,230	2,128
Unbilled revenues	547	1,012
Other accounts and notes	553	637
Fossil fuel stock	829	575
Materials and supplies	1,913	1,664
Regulatory assets – asset retirement obligations	358	332
Other regulatory assets	996	968
Other current assets	544	344
Total current assets	11,088	10,416
Property, Plant, and Equipment:
In service	125,573	117,529
Less: Accumulated depreciation	37,199	35,297
Plant in service, net of depreciation	88,374	82,232
Nuclear fuel, at amortized cost	862	843
Construction work in progress	8,496	10,896
Total property, plant, and equipment	98,254	94,570
Other Property and Investments:
Nuclear decommissioning trusts, at fair value	2,207	2,145
Equity investments in unconsolidated subsidiaries	1,376	1,443
Miscellaneous property and investments	651	602
Total other property and investments	9,772	9,757
Deferred Charges and Other Assets:
Operating lease right-of-use assets, net of amortization	1,467	1,531
Deferred charges related to income taxes	889	866
Prepaid pension costs	2,574	2,290
Deferred under recovered fuel clause revenues	1,279	2,056
Regulatory assets – asset retirement obligations, deferred	5,629	5,764
Other regulatory assets, deferred	5,666	5,918
Other deferred charges and assets	1,479	1,485
Total deferred charges and other assets	19,207	20,148
Total Assets	138,321	134,891
Current Liabilities:
Securities due within one year	3,076	4,285
Notes payable	1,726	2,609
Accounts payable —
Customer deposits	511	502
Accrued interest	573	614
Accrued compensation	936	1,127
Operating lease obligations	181	197
Asset retirement obligations	727	694
Other regulatory liabilities	163	382
Other current liabilities	943	787
Total current liabilities	13,214	15,724
Long-term Debt	56,003	50,656
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	10,774	10,036
Deferred credits related to income taxes	4,813	5,235
Accumulated deferred ITCs	2,071	2,133
Employee benefit obligations	1,184	1,238
Operating lease obligations, deferred	1,320	1,388
Asset retirement obligations, deferred	9,872	10,146
Other deferred credits and liabilities	1,166	1,167
Total deferred credits and other liabilities	33,800	33,979
Total Liabilities	103,017	100,359
Total Stockholders' Equity	35,304	34,532
Total Liabilities and Stockholders' Equity	138,321	134,891
GEORGIA POWER CO
Current Assets:
Cash and cash equivalents	173	364
Receivables —
Unbilled revenues	250	309
Under recovered fuel clause revenues	730	0
Joint owner accounts	157	128
Other accounts and notes	70	62
Fossil fuel stock	429	291
Materials and supplies	856	729
Regulatory assets – asset retirement obligations	183	158
Other regulatory assets	379	324
Other current assets	266	246
Total current assets	4,624	3,399
Property, Plant, and Equipment:
In service	48,083	41,879
Less: Accumulated depreciation	13,771	13,115
Plant in service, net of depreciation	34,312	28,764
Nuclear fuel, at amortized cost	622	604
Construction work in progress	5,055	8,103
Total property, plant, and equipment	39,989	37,471
Other Property and Investments:
Nuclear decommissioning trusts, at fair value	1,042	1,018
Equity investments in unconsolidated subsidiaries	47	51
Miscellaneous property and investments	131	107
Total other property and investments	1,220	1,176
Deferred Charges and Other Assets:
Operating lease right-of-use assets, net of amortization	914	1,007
Deferred charges related to income taxes	595	583
Prepaid pension costs	839	738
Deferred under recovered fuel clause revenues	1,279	2,056
Regulatory assets – asset retirement obligations, deferred	3,508	3,671
Other regulatory assets, deferred	2,685	2,522
Other deferred charges and assets	496	540
Total deferred charges and other assets	10,316	11,117
Total Assets	56,149	53,163
Current Liabilities:
Securities due within one year	503	901
Notes payable	1,250	1,600
Accounts payable —
Customer deposits	251	252
Accrued taxes	620	508
Accrued interest	178	157
Accrued compensation	205	254
Operating lease obligations	134	151
Asset retirement obligations	328	295
Other regulatory liabilities	22	170
Other current liabilities	421	286
Total current liabilities	6,314	6,578
Long-term Debt	15,522	14,009
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	3,914	3,707
Deferred credits related to income taxes	2,171	2,244
Accumulated deferred ITCs	311	319
Employee benefit obligations	291	318
Operating lease obligations, deferred	744	851
Asset retirement obligations, deferred	5,567	5,739
Other deferred credits and liabilities	458	540
Total deferred credits and other liabilities	13,456	13,718
Total Liabilities	35,292	34,305
Total Stockholders' Equity	20,857	18,858
Total Liabilities and Stockholders' Equity	56,149	53,163
GEORGIA POWER CO | Nonrelated Party
Receivables —
Customer accounts, net and Affiliated	1,056	735
Accounts payable —
Affiliated and Other	1,632	1,076
GEORGIA POWER CO | Related Party
Receivables —
Customer accounts, net and Affiliated	75	53
Accounts payable —
Affiliated and Other	$ 770	$ 928

Condensed Statements of Commo_2

Condensed Statements of Common Stockholders' Equity (Unaudited) - GPC - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Paid-In Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)	GEORGIA POWER CO	GEORGIA POWER CO Common Stock	GEORGIA POWER CO Paid-In Capital	GEORGIA POWER CO Retained Earnings (Accumulated Deficit)	GEORGIA POWER CO Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2021							9
Beginning balance at Dec. 31, 2021	$ 32,276	$ 5,279	$ 11,950	$ 10,929	$ (237)	$ 17,234	$ 398	$ 14,153	$ 2,724	$ (41)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income						385			385
Capital contributions from parent company						443		443
Other comprehensive income	42				42	10				10
Cash dividends on common stock	(702)			(702)		(423)			(423)
Other	7		7	2
Ending balance (in shares) at Mar. 31, 2022							9
Ending balance at Mar. 31, 2022	32,629	5,286	11,994	11,261	(195)	17,649	$ 398	14,596	2,686	(31)
Beginning balance (in shares) at Dec. 31, 2021							9
Beginning balance at Dec. 31, 2021	32,276	5,279	11,950	10,929	(237)	17,234	$ 398	14,153	2,724	(41)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income	3,566					1,851
Ending balance (in shares) at Sep. 30, 2022							9
Ending balance at Sep. 30, 2022	35,476	5,417	13,657	12,374	(157)	18,657	$ 398	14,966	3,307	(14)
Beginning balance (in shares) at Mar. 31, 2022							9
Beginning balance at Mar. 31, 2022	32,629	5,286	11,994	11,261	(195)	17,649	$ 398	14,596	2,686	(31)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income						608			608
Capital contributions from parent company						46		46
Other comprehensive income	11				11	16				16
Cash dividends on common stock	(723)			(723)		(422)			(422)
Other	2		4
Ending balance (in shares) at Jun. 30, 2022							9
Ending balance at Jun. 30, 2022	33,013	5,288	12,033	11,645	(184)	17,897	$ 398	14,642	2,872	(15)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income	1,487					858			858
Capital contributions from parent company						324		324
Other comprehensive income	28				28	1				1
Cash dividends on common stock	(741)			(741)		(423)			(423)
Other	(8)		(4)	(2)	(1)
Ending balance (in shares) at Sep. 30, 2022							9
Ending balance at Sep. 30, 2022	35,476	5,417	13,657	12,374	(157)	18,657	$ 398	14,966	3,307	(14)
Beginning balance (in shares) at Dec. 31, 2022							9
Beginning balance at Dec. 31, 2022	34,532	5,417	13,673	11,538	(167)	18,858	$ 398	15,626	2,846	(12)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income						296			296
Capital contributions from parent company						752		752
Other comprehensive income	(44)				(44)
Cash dividends on common stock	(742)			(742)		(464)			(464)
Other	0		2			1			1
Ending balance (in shares) at Mar. 31, 2023							9
Ending balance at Mar. 31, 2023	34,562	5,421	13,715	11,658	(211)	19,443	$ 398	16,378	2,679	(12)
Beginning balance (in shares) at Dec. 31, 2022							9
Beginning balance at Dec. 31, 2022	34,532	5,417	13,673	11,538	(167)	18,858	$ 398	15,626	2,846	(12)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income	3,053					1,547
Ending balance (in shares) at Sep. 30, 2023							9
Ending balance at Sep. 30, 2023	35,304	5,422	13,751	12,391	(130)	20,857	$ 398	17,467	3,002	(10)
Beginning balance (in shares) at Mar. 31, 2023							9
Beginning balance at Mar. 31, 2023	34,562	5,421	13,715	11,658	(211)	19,443	$ 398	16,378	2,679	(12)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income						471			471
Capital contributions from parent company						33		33
Other comprehensive income	43				43	1				1
Cash dividends on common stock	(764)			(764)		(464)			(464)
Other	0		2
Ending balance (in shares) at Jun. 30, 2023							9
Ending balance at Jun. 30, 2023	34,648	5,422	13,742	11,732	(168)	19,484	$ 398	16,411	2,686	(11)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income	1,432					780			780
Capital contributions from parent company						1,056		1,056
Other comprehensive income	38				38	1				1
Cash dividends on common stock	(765)			(765)		(464)			(464)
Other	(1)		(2)	2
Ending balance (in shares) at Sep. 30, 2023							9
Ending balance at Sep. 30, 2023	$ 35,304	$ 5,422	$ 13,751	$ 12,391	$ (130)	$ 20,857	$ 398	$ 17,467	$ 3,002	$ (10)

Condensed Statements of Incom_3

Condensed Statements of Income (Unaudited) - MPC - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Operating Revenues:
Total operating revenues	$ 6,980	$ 8,378	$ 19,208	$ 22,232
Operating Expenses:
Other operations and maintenance	1,424	1,527	4,352	4,568
Depreciation and amortization	1,143	922	3,365	2,728
Taxes other than income taxes	341	352	1,076	1,073
Total operating expenses	4,870	6,185	14,589	17,000
Operating Income	2,110	2,193	4,619	5,232
Other Income and (Expense):
Interest expense, net of amounts capitalized	(620)	(511)	(1,812)	(1,461)
Other income (expense), net	141	132	428	414
Total other income and (expense)	(381)	(292)	(1,074)	(775)
Earnings Before Income Taxes	1,729	1,901	3,545	4,457
Income taxes	297	414	492	891
Net Income	1,432	1,487	3,053	3,566
Retail electric revenues
Operating Revenues:
Total operating revenues	5,139	5,961	12,597	14,363
Wholesale electric revenues
Operating Revenues:
Total operating revenues	727	1,197	1,930	2,798
Other electric revenues
Operating Revenues:
Total operating revenues	203	185	602	554
Natural Gas
Operating Revenues:
Total operating revenues	689	857	3,417	3,998
Other revenues
Operating Revenues:
Total operating revenues	222	178	662	519
Operating Expenses:
Total cost of sales	126	92	381	275
Mississippi Power
Operating Revenues:
Total operating revenues	436	510	1,137	1,279
Operating Expenses:
Other operations and maintenance	84	86	258	252
Depreciation and amortization	48	45	139	135
Taxes other than income taxes	32	32	92	93
Total operating expenses	333	425	905	1,081
Operating Income	103	85	232	198
Other Income and (Expense):
Interest expense, net of amounts capitalized	(19)	(15)	(53)	(42)
Other income (expense), net	9	9	29	32
Total other income and (expense)	(10)	(6)	(24)	(10)
Earnings Before Income Taxes	93	79	208	188
Income taxes	18	17	35	38
Net Income	75	62	173	150
Mississippi Power | Retail electric revenues
Operating Revenues:
Total operating revenues	284	250	747	718
Mississippi Power | Wholesale revenues, non-affiliates
Operating Revenues:
Total operating revenues	77	60	201	191
Mississippi Power | Wholesale revenues, affiliates
Operating Revenues:
Total operating revenues	65	187	158	336
Mississippi Power | Other revenues
Operating Revenues:
Total operating revenues	10	13	31	34
Mississippi Power | Fuel and purchased power
Operating Expenses:
Total cost of sales	$ 169	$ 262	$ 416	$ 601

Condensed Statements of Cash _5

Condensed Statements of Cash Flows (Unaudited) - MPC - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Operating Activities:
Consolidated net income	$ 3,053	$ 3,566
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	3,699	3,084
Deferred income taxes	(52)	608
Pension, postretirement, and other employee benefits	(397)	(322)
Settlement of asset retirement obligations	(444)	(314)
Other, net	(67)	(119)
Changes in certain current assets and liabilities —
Receivables	524	(316)
Retail fuel cost under recovery	513	(104)
Other current assets	(32)	(310)
Accounts payable	(1,031)	805
Accrued taxes	376	167
Accrued compensation	(197)	(123)
Other current liabilities	66	(82)
Net cash provided from operating activities	5,740	5,017
Investing Activities:
Property additions	(6,561)	(5,502)
Cost of removal, net of salvage	(421)	(518)
Construction payables	241	15
Other investing activities	(139)	(63)
Net cash used for investing activities	(6,721)	(5,952)
Financing Activities:
Payment of common stock dividends	(2,271)	(2,166)
Other financing activities	(141)	(235)
Net cash provided from financing activities	834	1,119
Net Change in Cash, Cash Equivalents, and Restricted Cash	(147)	184
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	2,037	1,829
Cash, Cash Equivalents, and Restricted Cash at End of Period	1,890	2,013
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	1,694	1,425
Income taxes, net	11	160
Noncash transactions —
Accrued property additions at end of period	1,224	872
Right-of-use assets obtained under operating leases	76	27
Mississippi Power
Operating Activities:
Consolidated net income	173	150
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	171	164
Deferred income taxes	(10)	(4)
Pension, postretirement, and other employee benefits	(15)	(12)
Settlement of asset retirement obligations	(12)	(15)
Other, net	12	36
Changes in certain current assets and liabilities —
Receivables	55	(49)
Retail fuel cost under recovery	(24)	(9)
Other current assets	14	(17)
Accounts payable	(83)	41
Accrued taxes	(16)	(3)
Accrued compensation	(5)	(5)
Other current liabilities	0	2
Net cash provided from operating activities	260	279
Investing Activities:
Property additions	(231)	(165)
Cost of removal, net of salvage	(21)	(20)
Construction payables	(5)	(9)
Payments pursuant to LTSAs	(21)	(23)
Other investing activities	(2)	(2)
Net cash used for investing activities	(280)	(219)
Financing Activities:
Increase in notes payable, net	20	0
Proceeds — Senior notes	100	0
Capital contributions from parent company	8	55
Payment of common stock dividends	(139)	(128)
Other financing activities	(1)	1
Net cash provided from financing activities	(12)	(72)
Net Change in Cash, Cash Equivalents, and Restricted Cash	(32)	(12)
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	59	61
Cash, Cash Equivalents, and Restricted Cash at End of Period	27	49
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	53	49
Income taxes, net	33	18
Noncash transactions —
Accrued property additions at end of period	20	16
Right-of-use assets obtained under operating leases	1	0
GEORGIA POWER CO
Operating Activities:
Consolidated net income	1,547	1,851
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	1,411	1,211
Deferred income taxes	102	266
Pension, postretirement, and other employee benefits	(207)	(178)
Settlement of asset retirement obligations	(228)	(149)
Other, net	(12)	(22)
Changes in certain current assets and liabilities —
Receivables	(311)	(321)
Retail fuel cost under recovery	204	0
Other current assets	16	(72)
Accounts payable	(142)	211
Accrued taxes	118	151
Other current liabilities	16	(79)
Net cash provided from operating activities	1,969	1,482
Investing Activities:
Property additions	(3,501)	(2,556)
Cost of removal, net of salvage	(191)	(250)
Other investing activities	(76)	(47)
Net cash used for investing activities	(3,376)	(2,653)
Financing Activities:
Increase in notes payable, net	50	415
Proceeds — Senior notes	1,750	1,500
Capital contributions from parent company	1,837	813
Payment of common stock dividends	(1,392)	(1,268)
Other financing activities	(27)	(45)
Net cash provided from financing activities	1,183	1,171
Net Change in Cash, Cash Equivalents, and Restricted Cash	(224)	0
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	480	33
Cash, Cash Equivalents, and Restricted Cash at End of Period	256	33
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	439	332
Income taxes, net	74	151
Noncash transactions —
Accrued property additions at end of period	942	609
Right-of-use assets obtained under operating leases	$ 17	$ 7

Condensed Balance Sheets (Una_3

Condensed Balance Sheets (Unaudited) - MPC - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Current Assets:
Cash and cash equivalents	$ 1,676	$ 1,917
Receivables —
Customer accounts, net and Affiliated	2,230	2,128
Unbilled revenues	547	1,012
Other accounts and notes	553	637
Fossil fuel stock	829	575
Materials and supplies	1,913	1,664
Other regulatory assets	996	968
Other current assets	544	344
Total current assets	11,088	10,416
Property, Plant, and Equipment:
In service	125,573	117,529
Less: Accumulated depreciation	37,199	35,297
Plant in service, net of depreciation	88,374	82,232
Construction work in progress	8,496	10,896
Total property, plant, and equipment	98,254	94,570
Other Property and Investments:
Total other property and investments	9,772	9,757
Deferred Charges and Other Assets:
Deferred charges related to income taxes	889	866
Prepaid pension costs	2,574	2,290
Regulatory assets – asset retirement obligations	5,629	5,764
Other regulatory assets, deferred	5,666	5,918
Other deferred charges and assets	1,479	1,485
Total deferred charges and other assets	19,207	20,148
Total Assets	138,321	134,891
Current Liabilities:
Securities due within one year	3,076	4,285
Notes payable	1,726	2,609
Accounts payable —
Accrued compensation	936	1,127
Asset retirement obligations	727	694
Other regulatory liabilities	163	382
Other current liabilities	943	787
Total current liabilities	13,214	15,724
Long-term Debt	56,003	50,656
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	10,774	10,036
Deferred credits related to income taxes	4,813	5,235
Employee benefit obligations	1,184	1,238
Asset retirement obligations, deferred	9,872	10,146
Other cost of removal obligations	1,940	1,903
Other regulatory liabilities, deferred	660	733
Other deferred credits and liabilities	1,166	1,167
Total deferred credits and other liabilities	33,800	33,979
Total Liabilities	103,017	100,359
Total Liabilities and Stockholders' Equity	138,321	134,891
Mississippi Power
Current Assets:
Cash and cash equivalents	27	59
Receivables —
Unbilled revenues	41	47
Other accounts and notes	22	35
Fossil fuel stock	37	44
Materials and supplies	85	80
Other regulatory assets	54	72
Other current assets	10	38
Total current assets	392	504
Property, Plant, and Equipment:
In service	5,473	5,254
Less: Accumulated depreciation	1,763	1,689
Plant in service, net of depreciation	3,710	3,565
Construction work in progress	183	208
Total property, plant, and equipment	3,893	3,773
Other Property and Investments:
Total other property and investments	160	167
Deferred Charges and Other Assets:
Deferred charges related to income taxes	29	30
Prepaid pension costs	123	109
Regulatory assets – asset retirement obligations	241	239
Other regulatory assets, deferred	246	249
Accumulated deferred income taxes	95	107
Other deferred charges and assets	79	94
Total deferred charges and other assets	813	828
Total Assets	5,258	5,272
Current Liabilities:
Securities due within one year	201	1
Notes payable	20	0
Accounts payable —
Accrued taxes	108	124
Accrued compensation	32	37
Asset retirement obligations	26	37
Other regulatory liabilities	30	43
Other current liabilities	74	85
Total current liabilities	631	554
Long-term Debt	1,443	1,544
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	466	466
Deferred credits related to income taxes	229	253
Employee benefit obligations	67	69
Asset retirement obligations, deferred	145	142
Other cost of removal obligations	192	196
Other regulatory liabilities, deferred	81	96
Other deferred credits and liabilities	30	21
Total deferred credits and other liabilities	1,210	1,243
Total Liabilities	3,284	3,341
Total common stockholders' equity	1,974	1,931
Total Liabilities and Stockholders' Equity	5,258	5,272
Mississippi Power | Nonrelated Party
Receivables —
Customer accounts, net and Affiliated	78	47
Accounts payable —
Affiliated and Other	61	106
Mississippi Power | Related Party
Receivables —
Customer accounts, net and Affiliated	38	82
Accounts payable —
Affiliated and Other	$ 79	$ 121

Condensed Statements of Commo_3

Condensed Statements of Common Stockholders' Equity (Unaudited) - MPC - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Paid-In Capital	Retained Earnings (Accumulated Deficit)	Mississippi Power	Mississippi Power Common Stock	Mississippi Power Paid-In Capital	Mississippi Power Retained Earnings (Accumulated Deficit)
Beginning balance (in shares) at Dec. 31, 2021						1
Beginning balance at Dec. 31, 2021	$ 32,276	$ 5,279	$ 11,950	$ 10,929	$ 1,867	$ 38	$ 4,582	$ (2,753)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income					42			42
Capital contributions from parent company					51		51
Cash dividends on common stock	(702)			(702)	(43)			(43)
Ending balance (in shares) at Mar. 31, 2022						1
Ending balance at Mar. 31, 2022	32,629	5,286	11,994	11,261	1,917	$ 38	4,633	(2,754)
Beginning balance (in shares) at Dec. 31, 2021						1
Beginning balance at Dec. 31, 2021	32,276	5,279	11,950	10,929	1,867	$ 38	4,582	(2,753)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	3,566				150
Ending balance (in shares) at Sep. 30, 2022						1
Ending balance at Sep. 30, 2022	35,476	5,417	13,657	12,374	1,946	$ 38	4,639	(2,731)
Beginning balance (in shares) at Mar. 31, 2022						1
Beginning balance at Mar. 31, 2022	32,629	5,286	11,994	11,261	1,917	$ 38	4,633	(2,754)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income					45			45
Capital contributions from parent company					1		1
Cash dividends on common stock	(723)			(723)	(42)			(42)
Ending balance (in shares) at Jun. 30, 2022						1
Ending balance at Jun. 30, 2022	33,013	5,288	12,033	11,645	1,921	$ 38	4,634	(2,751)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,487				62			62
Capital contributions from parent company					5		5
Cash dividends on common stock	(741)			(741)	(42)			(42)
Ending balance (in shares) at Sep. 30, 2022						1
Ending balance at Sep. 30, 2022	35,476	5,417	13,657	12,374	1,946	$ 38	4,639	(2,731)
Beginning balance (in shares) at Dec. 31, 2022						1
Beginning balance at Dec. 31, 2022	34,532	5,417	13,673	11,538	1,931	$ 38	4,652	(2,759)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income					58			58
Cash dividends on common stock	(742)			(742)	(46)			(46)
Ending balance (in shares) at Mar. 31, 2023						1
Ending balance at Mar. 31, 2023	34,562	5,421	13,715	11,658	1,943	$ 38	4,652	(2,747)
Beginning balance (in shares) at Dec. 31, 2022						1
Beginning balance at Dec. 31, 2022	34,532	5,417	13,673	11,538	1,931	$ 38	4,652	(2,759)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	3,053				173
Ending balance (in shares) at Sep. 30, 2023						1
Ending balance at Sep. 30, 2023	35,304	5,422	13,751	12,391	1,974	$ 38	4,661	(2,725)
Beginning balance (in shares) at Mar. 31, 2023						1
Beginning balance at Mar. 31, 2023	34,562	5,421	13,715	11,658	1,943	$ 38	4,652	(2,747)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income					40			40
Capital contributions from parent company					12		12
Cash dividends on common stock	(764)			(764)	(47)			(47)
Ending balance (in shares) at Jun. 30, 2023						1
Ending balance at Jun. 30, 2023	34,648	5,422	13,742	11,732	1,948	$ 38	4,664	(2,754)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,432				75			75
Return of capital to parent company					(3)		(3)
Cash dividends on common stock	(765)			(765)	(46)			(46)
Ending balance (in shares) at Sep. 30, 2023						1
Ending balance at Sep. 30, 2023	$ 35,304	$ 5,422	$ 13,751	$ 12,391	$ 1,974	$ 38	$ 4,661	$ (2,725)

Condensed Consolidated Statem_9

Condensed Consolidated Statements of Income (Unaudited) - SPC - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Operating Revenues:
Total operating revenues	$ 6,980	$ 8,378	$ 19,208	$ 22,232
Operating Expenses:
Other operations and maintenance	1,424	1,527	4,352	4,568
Depreciation and amortization	1,143	922	3,365	2,728
Taxes other than income taxes	341	352	1,076	1,073
Total operating expenses	4,870	6,185	14,589	17,000
Operating Income	2,110	2,193	4,619	5,232
Other Income and (Expense):
Interest expense, net of amounts capitalized	(620)	(511)	(1,812)	(1,461)
Other income (expense), net	141	132	428	414
Total other income and (expense)	(381)	(292)	(1,074)	(775)
Earnings Before Income Taxes	1,729	1,901	3,545	4,457
Income taxes	297	414	492	891
Net Income	1,432	1,487	3,053	3,566
Net income (loss) attributable to noncontrolling interests	10	12	(68)	(55)
Net Income	1,422	1,472	3,121	3,611
Retail electric revenues
Operating Revenues:
Total operating revenues	5,139	5,961	12,597	14,363
Wholesale electric revenues
Operating Revenues:
Total operating revenues	727	1,197	1,930	2,798
Other electric revenues
Operating Revenues:
Total operating revenues	203	185	602	554
Natural Gas
Operating Revenues:
Total operating revenues	689	857	3,417	3,998
Other revenues
Operating Revenues:
Total operating revenues	222	178	662	519
Operating Expenses:
Total cost of sales	126	92	381	275
Fuel
Operating Expenses:
Total cost of sales	1,367	2,423	3,376	5,249
Purchased power
Operating Expenses:
Total cost of sales	207	645	680	1,285
SOUTHERN POWER CO
Operating Revenues:
Total operating revenues	653	1,180	1,686	2,618
Operating Expenses:
Other operations and maintenance	104	113	327	332
Depreciation and amortization	130	133	380	384
Taxes other than income taxes	13	13	38	38
Gain on dispositions, net	0	0	(20)	(2)
Total operating expenses	476	1,008	1,338	2,259
Operating Income	177	172	348	359
Other Income and (Expense):
Interest expense, net of amounts capitalized	(32)	(32)	(98)	(105)
Other income (expense), net	4	3	8	5
Total other income and (expense)	(28)	(29)	(90)	(100)
Earnings Before Income Taxes	149	143	258	259
Income taxes	39	36	38	49
Net Income	110	107	220	210
Net income (loss) attributable to noncontrolling interests	10	12	(68)	(55)
Net Income	100	95	288	265
SOUTHERN POWER CO | Wholesale revenues, non-affiliates
Operating Revenues:
Total operating revenues	479	835	1,234	1,918
SOUTHERN POWER CO | Wholesale revenues, affiliates
Operating Revenues:
Total operating revenues	156	336	406	673
SOUTHERN POWER CO | Other revenues
Operating Revenues:
Total operating revenues	18	9	46	27
SOUTHERN POWER CO | Fuel
Operating Expenses:
Total cost of sales	196	605	526	1,274
SOUTHERN POWER CO | Purchased power
Operating Expenses:
Total cost of sales	$ 33	$ 144	$ 87	$ 233

Condensed Consolidated State_10

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - SPC - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Consolidated Net Income	$ 1,432	$ 1,487	$ 3,053	$ 3,566
Qualifying hedges:
Changes in fair value, net of tax	2	0	(34)	(27)
Reclassification adjustment for amounts included in net income, net of tax	36	26	70	100
Reclassification adjustment for amounts included in net income, net of tax	0	2	1	8
Total other comprehensive income	38	28	37	81
Comprehensive income	1,470	1,515	3,090	3,647
Comprehensive income (loss) attributable to noncontrolling interests	10	12	(68)	(55)
Comprehensive Income	1,460	1,500	3,158	3,692
SOUTHERN POWER CO
Consolidated Net Income	110	107	220	210
Qualifying hedges:
Changes in fair value, net of tax	(13)	(35)	(17)	(106)
Reclassification adjustment for amounts included in net income, net of tax	17	28	24	106
Reclassification adjustment for amounts included in net income, net of tax	0	0	0	1
Total other comprehensive income	4	(7)	7	1
Comprehensive income	114	100	227	211
Comprehensive income (loss) attributable to noncontrolling interests	10	12	(68)	(55)
Comprehensive Income	$ 104	$ 88	$ 295	$ 266

Condensed Consolidated State_11

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - SPC (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Changes in fair value, tax	$ 3	$ 2	$ (11)	$ (5)
Qualifying hedges, reclassification adjustment, tax	12	8	25	32
Reclassification adjustment for amounts included in net income, tax	0	1	0	3
SOUTHERN POWER CO
Changes in fair value, tax	(2)	(11)	(3)	(35)
Qualifying hedges, reclassification adjustment, tax	4	9	6	35
Reclassification adjustment for amounts included in net income, tax	$ 0	$ 0	$ 0	$ 0

Condensed Consolidated State_12

Condensed Consolidated Statements of Cash Flows (Unaudited) - SPC - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Operating Activities:
Consolidated net income	$ 3,053	$ 3,566
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	3,699	3,084
Deferred income taxes	(52)	608
Utilization of federal investment tax credits	195	266
Other, net	(67)	(119)
Changes in certain current assets and liabilities —
Receivables	524	(316)
Other current assets	(32)	(310)
Accounts payable	(1,031)	805
Accrued taxes	376	167
Other current liabilities	66	(82)
Net cash provided from operating activities	5,740	5,017
Investing Activities:
Property additions	(6,561)	(5,502)
Other investing activities	(139)	(63)
Net cash used for investing activities	(6,721)	(5,952)
Financing Activities:
Increase (decrease) in notes payable, net	(298)	(349)
Capital contributions from noncontrolling interests	21	73
Distributions to noncontrolling interests	(148)	(175)
Payment of common stock dividends	(2,271)	(2,166)
Other financing activities	(141)	(235)
Net cash provided from financing activities	834	1,119
Net Change in Cash, Cash Equivalents, and Restricted Cash	(147)	184
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	2,037	1,829
Cash, Cash Equivalents, and Restricted Cash at End of Period	1,890	2,013
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	1,694	1,425
Income taxes, net	11	160
Noncash transactions —
Accrued property additions at end of period	1,224	872
Right-of-use assets obtained under operating leases	76	27
Reassessment of right-of-use assets under operating leases	0	40
SOUTHERN POWER CO
Operating Activities:
Consolidated net income	220	210
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	395	404
Deferred income taxes	1	21
Utilization of federal investment tax credits	179	218
Amortization of investment tax credits	(44)	(44)
Gain on dispositions, net	(20)	(2)
Other, net	4	1
Changes in certain current assets and liabilities —
Receivables	100	(124)
Prepaid income taxes	31	22
Other current assets	(14)	(15)
Accounts payable	(70)	95
Accrued taxes	9	55
Other current liabilities	8	(14)
Net cash provided from operating activities	799	827
Investing Activities:
Acquisitions, net of cash acquired	(181)	0
Property additions	(40)	(64)
Proceeds from dispositions	59	48
Change in construction payables	(18)	(60)
Payments pursuant to LTSAs	(49)	(52)
Other investing activities	5	0
Net cash used for investing activities	(224)	(128)
Financing Activities:
Increase (decrease) in notes payable, net	136
Increase (decrease) in notes payable, net		(5)
Redemptions — Senior notes	(290)	(677)
Capital contributions from parent company	16	330
Capital contributions from noncontrolling interests	21	73
Distributions to noncontrolling interests	(148)	(175)
Payment of common stock dividends	(189)	(148)
Other financing activities	3	(1)
Net cash provided from financing activities	(451)	(603)
Net Change in Cash, Cash Equivalents, and Restricted Cash	124	96
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	133	135
Cash, Cash Equivalents, and Restricted Cash at End of Period	257	231
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	103	120
Income taxes, net	(124)	(202)
Noncash transactions —
Accrued property additions at end of period	23	30
Right-of-use assets obtained under operating leases	7	0
Reassessment of right-of-use assets under operating leases	$ 0	$ 40

Condensed Consolidated State_13

Condensed Consolidated Statements of Cash Flows (Unaudited) - SPC (Parenthetical) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Net cash paid for capitalized interest	$ 97	$ 74
SOUTHERN POWER CO
Net cash paid for capitalized interest	$ 1	$ 0

Condensed Consolidated Balanc_3

Condensed Consolidated Balance Sheets (Unaudited) - SPC - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Current Assets:
Cash and cash equivalents	$ 1,676	$ 1,917
Receivables —
Customer accounts, net and Affiliated	2,230	2,128
Other	553	637
Materials and supplies	1,913	1,664
Other current assets	544	344
Total current assets	11,088	10,416
Property, Plant, and Equipment:
In service	125,573	117,529
Less: Accumulated depreciation	37,199	35,297
Plant in service, net of depreciation	88,374	82,232
Construction work in progress	8,496	10,896
Total property, plant, and equipment	98,254	94,570
Other Property and Investments:
Equity investments in unconsolidated subsidiaries	1,376	1,443
Total other property and investments	9,772	9,757
Deferred Charges and Other Assets:
Operating lease right-of-use assets, net of amortization	1,467	1,531
Other deferred charges and assets	1,479	1,485
Total deferred charges and other assets	19,207	20,148
Total Assets	138,321	134,891
Current Liabilities:
Securities due within one year	3,076	4,285
Notes payable	1,726	2,609
Accounts payable —
Accrued interest	573	614
Other current liabilities	943	787
Total current liabilities	13,214	15,724
Long-term Debt	56,003	50,656
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	10,774	10,036
Accumulated deferred ITCs	2,071	2,133
Operating lease obligations	1,320	1,388
Other deferred credits and liabilities	1,166	1,167
Total deferred credits and other liabilities	33,800	33,979
Total Liabilities	103,017	100,359
Total Stockholders' Equity (See accompanying statements)	35,304	34,532
Total Liabilities and Stockholders' Equity	138,321	134,891
SOUTHERN POWER CO
Current Assets:
Cash and cash equivalents	236	131
Receivables —
Other	44	70
Materials and supplies	84	88
Prepaid income taxes	130	5
Other current assets	71	50
Total current assets	789	621
Property, Plant, and Equipment:
In service	14,678	14,658
Less: Accumulated depreciation	4,001	3,661
Plant in service, net of depreciation	10,677	10,997
Construction work in progress	224	41
Total property, plant, and equipment	10,901	11,038
Other Property and Investments:
Intangible assets, net of amortization	248	263
Equity investments in unconsolidated subsidiaries	0	49
Net investment in sales-type leases	150	154
Total other property and investments	398	466
Deferred Charges and Other Assets:
Operating lease right-of-use assets, net of amortization	490	489
Prepaid LTSAs	225	193
Other deferred charges and assets	287	274
Total deferred charges and other assets	1,002	956
Total Assets	13,090	13,081
Current Liabilities:
Securities due within one year	0	290
Notes payable	359	225
Accounts payable —
Accrued taxes	33	24
Accrued interest	22	28
Other current liabilities	117	111
Total current liabilities	654	884
Long-term Debt	2,687	2,689
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	619	279
Accumulated deferred ITCs	1,512	1,556
Operating lease obligations	516	514
Other deferred credits and liabilities	259	243
Total deferred credits and other liabilities	2,906	2,592
Total Liabilities	6,247	6,165
Total Stockholders' Equity (See accompanying statements)	6,843	6,916
Total Liabilities and Stockholders' Equity	13,090	13,081
SOUTHERN POWER CO | Nonrelated Party
Receivables —
Customer accounts, net and Affiliated	164	226
Accounts payable —
Affiliated and Other	43	67
SOUTHERN POWER CO | Related Party
Receivables —
Customer accounts, net and Affiliated	60	51
Accounts payable —
Affiliated and Other	$ 80	$ 139

Condensed Consolidated Balanc_4

Condensed Consolidated Balance Sheets (Unaudited) - SPC (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Other intangible assets, amortization	$ 367	$ 340
SOUTHERN POWER CO
Other intangible assets, amortization	$ 143	$ 129

Condensed Consolidated State_14

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - SPC - USD ($) $ in Millions	Total	Paid-In Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests	SOUTHERN POWER CO	SOUTHERN POWER CO Total Common Stockholders' Equity	SOUTHERN POWER CO Paid-In Capital	SOUTHERN POWER CO Retained Earnings (Accumulated Deficit)	SOUTHERN POWER CO Accumulated Other Comprehensive Income (Loss)	SOUTHERN POWER CO Noncontrolling Interests
Beginning balance at Dec. 31, 2021	$ 32,276	$ 11,950	$ 10,929	$ (237)	$ 4,402	$ 6,598	$ 2,196	$ 638	$ 1,585	$ (27)	$ 4,402
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income						27	72		72		(45)
Other comprehensive income	42			42		5	5			5
Cash dividends on common stock	(702)		(702)			(49)	(49)		(49)
Capital contributions from noncontrolling interests	73				73	73					73
Distributions to noncontrolling interests	(98)				(98)	(98)					(98)
Other	7	7	2
Ending balance at Mar. 31, 2022	32,629	11,994	11,261	(195)	4,332	6,556	2,224	638	1,608	(22)	4,332
Beginning balance at Dec. 31, 2021	32,276	11,950	10,929	(237)	4,402	6,598	2,196	638	1,585	(27)	4,402
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income	3,566					210
Ending balance at Sep. 30, 2022	35,476	13,657	12,374	(157)	4,237	6,880	2,643	969	1,701	(27)	4,237
Beginning balance at Mar. 31, 2022	32,629	11,994	11,261	(195)	4,332	6,556	2,224	638	1,608	(22)	4,332
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income						76	98		98		(22)
Capital contributions from parent company						322	322	322
Other comprehensive income	11			11		3	3			3
Cash dividends on common stock	(723)		(723)			(50)	(50)		(50)
Distributions to noncontrolling interests	(28)				(28)	(28)					(28)
Other	2	4
Ending balance at Jun. 30, 2022	33,013	12,033	11,645	(184)	4,282	6,879	2,597	960	1,656	(19)	4,282
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income	1,487					107	95		95		12
Capital contributions from parent company						9	9	9
Other comprehensive income	28			28		(7)	(7)			(7)
Cash dividends on common stock	(741)		(741)			(49)	(49)		(49)
Distributions to noncontrolling interests	(57)				(57)	(57)					(57)
Other	(8)	(4)	(2)	(1)		(2)	(2)		(1)	(1)
Ending balance at Sep. 30, 2022	35,476	13,657	12,374	(157)	4,237	6,880	2,643	969	1,701	(27)	4,237
Beginning balance at Dec. 31, 2022	34,532	13,673	11,538	(167)	4,124	6,916	2,792	1,069	1,741	(18)	4,124
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income						39	102		102		(63)
Other comprehensive income	(44)			(44)		(7)	(7)			(7)
Cash dividends on common stock	(742)		(742)			(63)	(63)		(63)
Capital contributions from noncontrolling interests	21				21	21					21
Distributions to noncontrolling interests	(48)				(48)	(48)					(48)
Other	0	2
Ending balance at Mar. 31, 2023	34,562	13,715	11,658	(211)	4,034	6,858	2,824	1,069	1,780	(25)	4,034
Beginning balance at Dec. 31, 2022	34,532	13,673	11,538	(167)	4,124	6,916	2,792	1,069	1,741	(18)	4,124
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income	3,053					220
Ending balance at Sep. 30, 2023	35,304	13,751	12,391	(130)	3,927	6,843	2,916	1,087	1,839	(10)	3,927
Beginning balance at Mar. 31, 2023	34,562	13,715	11,658	(211)	4,034	6,858	2,824	1,069	1,780	(25)	4,034
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income						70	85		85		(15)
Capital contributions from parent company						14	14	14
Other comprehensive income	43			43		10	10			10
Cash dividends on common stock	(764)		(764)			(63)	(63)		(63)
Distributions to noncontrolling interests	(42)				(42)	(42)					(42)
Other	0	2			(1)	0	1			1	(1)
Ending balance at Jun. 30, 2023	34,648	13,742	11,732	(168)	3,976	6,847	2,871	1,083	1,802	(14)	3,976
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income	1,432					110	100		100		10
Capital contributions from parent company						3	3	3
Other comprehensive income	38			38		4	4			4
Cash dividends on common stock	(765)		(765)			(63)	(63)		(63)
Distributions to noncontrolling interests	(59)				(59)	(59)					(59)
Other	(1)	(2)	2			1	1	1	0	0	0
Ending balance at Sep. 30, 2023	$ 35,304	$ 13,751	$ 12,391	$ (130)	$ 3,927	$ 6,843	$ 2,916	$ 1,087	$ 1,839	$ (10)	$ 3,927

Condensed Consolidated State_15

Condensed Consolidated Statements of Income (Unaudited) - GAS - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Operating Revenues:
Total operating revenues	$ 6,980	$ 8,378	$ 19,208	$ 22,232
Operating Expenses:
Other operations and maintenance	1,424	1,527	4,352	4,568
Depreciation and amortization	1,143	922	3,365	2,728
Taxes other than income taxes	341	352	1,076	1,073
Total operating expenses	4,870	6,185	14,589	17,000
Operating Income	2,110	2,193	4,619	5,232
Other Income and (Expense):
Earnings from equity method investments	32	28	110	109
Interest expense, net of amounts capitalized	(620)	(511)	(1,812)	(1,461)
Other income (expense), net	141	132	428	414
Total other income and (expense)	(381)	(292)	(1,074)	(775)
Earnings Before Income Taxes	1,729	1,901	3,545	4,457
Income taxes	297	414	492	891
Net Income	1,432	1,487	3,053	3,566
Retail electric revenues
Operating Revenues:
Total operating revenues	5,139	5,961	12,597	14,363
Wholesale electric revenues
Operating Revenues:
Total operating revenues	727	1,197	1,930	2,798
Other electric revenues
Operating Revenues:
Total operating revenues	203	185	602	554
Natural Gas
Operating Revenues:
Total operating revenues	689	857	3,417	3,998
Natural gas
Operating Expenses:
Total cost of sales	102	294	1,199	1,840
Other revenues
Operating Revenues:
Total operating revenues	222	178	662	519
Operating Expenses:
Total cost of sales	126	92	381	275
Fuel
Operating Expenses:
Total cost of sales	1,367	2,423	3,376	5,249
Purchased power
Operating Expenses:
Total cost of sales	207	645	680	1,285
SOUTHERN Co GAS
Operating Revenues:
Total operating revenues	$ 689	$ 857	$ 3,417	$ 3,998
Operating Expenses:
Cost, Product and Service [Extensible Enumeration]	Natural gas	Natural gas	Natural gas	Natural gas
Other operations and maintenance	$ 264	$ 252	$ 879	$ 824
Depreciation and amortization	145	140	429	414
Taxes other than income taxes	42	45	203	208
Total operating expenses	553	731	2,710	3,286
Operating Income	136	126	707	712
Other Income and (Expense):
Earnings from equity method investments	32	34	104	105
Interest expense, net of amounts capitalized	(77)	(65)	(226)	(187)
Other income (expense), net	19	15	50	47
Total other income and (expense)	(26)	(16)	(72)	(35)
Earnings Before Income Taxes	110	110	635	677
Income taxes	28	27	160	161
Net Income	82	83	475	516
SOUTHERN Co GAS | Natural gas
Operating Revenues:
Total operating revenues	689	857	3,417	3,998
Operating Expenses:
Total cost of sales	$ 102	$ 294	$ 1,199	$ 1,840

Condensed Consolidated State_16

Condensed Consolidated Statements of Income (Unaudited) - GAS (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
SOUTHERN Co GAS
Revenue taxes collected	$ 11	$ 15	$ 103	$ 118

Condensed Consolidated State_17

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - GAS - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Consolidated Net Income	$ 1,432	$ 1,487	$ 3,053	$ 3,566
Qualifying hedges:
Changes in fair value, net of tax	2	0	(34)	(27)
Reclassification adjustment for amounts included in net income, net of tax	36	26	70	100
Total other comprehensive income	38	28	37	81
Comprehensive Income	1,470	1,515	3,090	3,647
SOUTHERN Co GAS
Consolidated Net Income	82	83	475	516
Qualifying hedges:
Changes in fair value, net of tax	(6)	19	(30)	39
Reclassification adjustment for amounts included in net income, net of tax	16	(5)	37	(17)
Total other comprehensive income	10	14	7	22
Comprehensive Income	$ 92	$ 97	$ 482	$ 538

Condensed Consolidated State_18

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - GAS (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Changes in fair value, tax	$ 3	$ 2	$ (11)	$ (5)
Qualifying hedges, reclassification adjustment, tax	12	8	25	32
SOUTHERN Co GAS
Changes in fair value, tax	(2)	8	(11)	16
Qualifying hedges, reclassification adjustment, tax	$ 7	$ (2)	$ 15	$ (7)

Condensed Consolidated State_19

Condensed Consolidated Statements of Cash Flows (Unaudited) - GAS - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Operating Activities:
Consolidated net income	$ 3,053	$ 3,566
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	3,699	3,084
Deferred income taxes	(52)	608
Natural gas cost under recovery – long-term	0	207
Other, net	(67)	(119)
Changes in certain current assets and liabilities —
Receivables	524	(316)
Natural gas cost under recovery	108	(124)
Other current assets	(32)	(310)
Accounts payable	(1,031)	805
Other current liabilities	66	(82)
Net cash provided from operating activities	5,740	5,017
Investing Activities:
Property additions	(6,561)	(5,502)
Cost of removal, net of salvage	(421)	(518)
Change in construction payables, net	241	15
Other investing activities	(139)	(63)
Net cash used for investing activities	(6,721)	(5,952)
Financing Activities:
Decrease in notes payable, net	(298)	(349)
Proceeds —
Short-term borrowings	250	1,200
Redemptions —
Short-term borrowings	(850)	(900)
Payment of common stock dividends	(2,271)	(2,166)
Other financing activities	(141)	(235)
Net cash provided from financing activities	834	1,119
Net Change in Cash, Cash Equivalents, and Restricted Cash	(147)	184
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	2,037	1,829
Cash, Cash Equivalents, and Restricted Cash at End of Period	1,890	2,013
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	1,694	1,425
Income taxes, net	11	160
Accrued property additions at end of period	1,224	872
Right-of-use assets obtained under operating leases	76	27
SOUTHERN Co GAS
Operating Activities:
Consolidated net income	475	516
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	429	414
Deferred income taxes	75	109
Natural gas cost under recovery – long-term	0	207
Other, net	(15)	(12)
Changes in certain current assets and liabilities —
Receivables	776	301
Natural gas for sale, net of temporary LIFO liquidation	31	(136)
Prepaid income taxes	12	(77)
Natural gas cost under recovery	108	(124)
Other current assets	(32)	7
Accounts payable	(346)	342
Natural gas cost over recovery	165	0
Other current liabilities	(34)	(15)
Net cash provided from operating activities	1,644	1,532
Investing Activities:
Property additions	(1,151)	(1,063)
Cost of removal, net of salvage	(82)	(84)
Change in construction payables, net	(38)	(103)
Other investing activities	45	11
Net cash used for investing activities	(1,226)	(1,239)
Financing Activities:
Decrease in notes payable, net	(493)	(749)
Proceeds —
Proceeds — Senior notes	500	500
First mortgage bonds	125	100
Short-term borrowings	0	50
Other long-term debt	29	0
Redemptions —
Short-term borrowings	(200)	(150)
Medium-term notes	0	(46)
Capital contributions from parent company	377	357
Payment of common stock dividends	(439)	(389)
Other financing activities	(1)	14
Net cash provided from financing activities	(102)	(313)
Net Change in Cash, Cash Equivalents, and Restricted Cash	316	(20)
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	83	48
Cash, Cash Equivalents, and Restricted Cash at End of Period	399	28
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	214	186
Income taxes, net	70	193
Accrued property additions at end of period	139	10
Right-of-use assets obtained under operating leases	$ 3	$ 0

Condensed Consolidated State_20

Condensed Consolidated Statements of Cash Flows (Unaudited) - GAS (Parenthetical) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Net cash paid for capitalized interest	$ 97	$ 74
SOUTHERN Co GAS
Net cash paid for capitalized interest	$ 12	$ 7

Condensed Consolidated Balanc_5

Condensed Consolidated Balance Sheets (Unaudited) - GAS - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Current Assets:
Cash and cash equivalents	$ 1,676	$ 1,917
Receivables —
Customer accounts	2,230	2,128
Unbilled revenues	547	1,012
Other accounts and notes	553	637
Accumulated provision for uncollectible accounts	(78)	(71)
Natural gas for sale	406	438
Prepaid expenses	321	347
Other regulatory assets	996	968
Other current assets	544	344
Total current assets	11,088	10,416
Property, Plant, and Equipment:
In service	125,573	117,529
Less: Accumulated depreciation	37,199	35,297
Plant in service, net of depreciation	88,374	82,232
Construction work in progress	8,496	10,896
Total property, plant, and equipment	98,254	94,570
Other Property and Investments:
Goodwill	5,161	5,161
Equity investments in unconsolidated subsidiaries	1,376	1,443
Other intangible assets, net of amortization	377	406
Miscellaneous property and investments	651	602
Total other property and investments	9,772	9,757
Deferred Charges and Other Assets:
Operating lease right-of-use assets, net of amortization	1,467	1,531
Prepaid pension costs	2,574	2,290
Other regulatory assets, deferred	5,666	5,918
Other deferred charges and assets	1,479	1,485
Total deferred charges and other assets	19,207	20,148
Total Assets	138,321	134,891
Current Liabilities:
Securities due within one year	3,076	4,285
Notes payable	1,726	2,609
Accounts payable —
Customer deposits	511	502
Accrued interest	573	614
Accrued compensation	936	1,127
Natural gas cost over recovery	165	0
Other regulatory liabilities	163	382
Other current liabilities	943	787
Total current liabilities	13,214	15,724
Long-term Debt	56,003	50,656
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	10,774	10,036
Deferred credits related to income taxes	4,813	5,235
Employee benefit obligations	1,184	1,238
Operating lease obligations	1,320	1,388
Other cost of removal obligations	1,940	1,903
Other deferred credits and liabilities	1,166	1,167
Total deferred credits and other liabilities	33,800	33,979
Total Liabilities	103,017	100,359
Total Stockholders' Equity	35,304	34,532
Total Liabilities and Stockholders' Equity	138,321	134,891
SOUTHERN Co GAS
Current Assets:
Cash and cash equivalents	397	81
Receivables —
Customer accounts	242	616
Unbilled revenues	74	453
Other accounts and notes	52	76
Accumulated provision for uncollectible accounts	(53)	(50)
Natural gas for sale	406	438
Prepaid expenses	92	93
Natural gas cost under recovery	0	108
Other regulatory assets	144	119
Other current assets	108	104
Total current assets	1,462	2,038
Property, Plant, and Equipment:
In service	20,459	19,723
Less: Accumulated depreciation	5,454	5,276
Plant in service, net of depreciation	15,005	14,447
Construction work in progress	1,158	909
Total property, plant, and equipment	16,163	15,356
Other Property and Investments:
Goodwill	5,015	5,015
Equity investments in unconsolidated subsidiaries	1,243	1,276
Other intangible assets, net of amortization	19	26
Miscellaneous property and investments	24	28
Total other property and investments	6,301	6,345
Deferred Charges and Other Assets:
Operating lease right-of-use assets, net of amortization	47	57
Prepaid pension costs	205	183
Other regulatory assets, deferred	483	497
Other deferred charges and assets	162	145
Total deferred charges and other assets	897	882
Total Assets	24,823	24,621
Current Liabilities:
Securities due within one year	400	400
Notes payable	75	768
Accounts payable —
Customer deposits	133	125
Accrued taxes	75	77
Accrued interest	79	67
Accrued compensation	85	105
Natural gas cost over recovery	165	0
Other regulatory liabilities	44	36
Other current liabilities	146	187
Total current liabilities	1,638	2,570
Long-term Debt	7,657	7,042
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	1,629	1,560
Deferred credits related to income taxes	766	788
Employee benefit obligations	108	120
Operating lease obligations	40	51
Other cost of removal obligations	1,748	1,707
Accrued environmental remediation	202	207
Other deferred credits and liabilities	202	179
Total deferred credits and other liabilities	4,695	4,612
Total Liabilities	13,990	14,224
Total Stockholders' Equity	10,833	10,397
Total Liabilities and Stockholders' Equity	24,823	24,621
SOUTHERN Co GAS | Related Party
Accounts payable —
Affiliated and Other	62	104
SOUTHERN Co GAS | Nonrelated Party
Accounts payable —
Affiliated and Other	$ 374	$ 701

Condensed Consolidated Balanc_6

Condensed Consolidated Balance Sheets (Unaudited) - GAS (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Other intangible assets, amortization	$ 367	$ 340
SOUTHERN Co GAS
Other intangible assets, amortization	$ 163	$ 156

Condensed Consolidated State_21

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - GAS - USD ($) $ in Millions	Total	Paid-In Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)	SOUTHERN Co GAS	SOUTHERN Co GAS Paid-In Capital	SOUTHERN Co GAS Retained Earnings (Accumulated Deficit)	SOUTHERN Co GAS Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2021	$ 32,276	$ 11,950	$ 10,929	$ (237)	$ 9,916	$ 10,024	$ (132)	$ 24
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income					319		319
Capital contributions from parent company					50	50
Other comprehensive income	42			42	20			20
Cash dividends on common stock	(702)		(702)		(130)		(130)
Other	7	7	2
Ending balance at Mar. 31, 2022	32,629	11,994	11,261	(195)	10,175	10,074	57	44
Beginning balance at Dec. 31, 2021	32,276	11,950	10,929	(237)	9,916	10,024	(132)	24
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income	3,566				516
Ending balance at Sep. 30, 2022	35,476	13,657	12,374	(157)	10,438	10,397	(5)	46
Beginning balance at Mar. 31, 2022	32,629	11,994	11,261	(195)	10,175	10,074	57	44
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income					115		115
Capital contributions from parent company					312	312
Other comprehensive income	11			11	(12)			(12)
Cash dividends on common stock	(723)		(723)		(130)		(130)
Other	2	4
Ending balance at Jun. 30, 2022	33,013	12,033	11,645	(184)	10,460	10,386	42	32
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income	1,487				83		83
Capital contributions from parent company					11	11
Other comprehensive income	28			28	14			14
Cash dividends on common stock	(741)		(741)		(130)		(130)
Other	(8)	(4)	(2)	(1)
Ending balance at Sep. 30, 2022	35,476	13,657	12,374	(157)	10,438	10,397	(5)	46
Beginning balance at Dec. 31, 2022	34,532	13,673	11,538	(167)	10,397	10,445	(79)	31
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income					309		309
Capital contributions from parent company					203	203
Other comprehensive income	(44)			(44)	(10)			(10)
Cash dividends on common stock	(742)		(742)		(146)		(146)
Other	0	2			0	1	(1)
Ending balance at Mar. 31, 2023	34,562	13,715	11,658	(211)	10,753	10,649	83	21
Beginning balance at Dec. 31, 2022	34,532	13,673	11,538	(167)	10,397	10,445	(79)	31
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income	3,053				475
Ending balance at Sep. 30, 2023	35,304	13,751	12,391	(130)	10,833	10,838	(43)	38
Beginning balance at Mar. 31, 2023	34,562	13,715	11,658	(211)	10,753	10,649	83	21
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income					85		85
Capital contributions from parent company					40	40
Other comprehensive income	43			43	7			7
Cash dividends on common stock	(764)		(764)		(147)		(147)
Other	0	2
Ending balance at Jun. 30, 2023	34,648	13,742	11,732	(168)	10,738	10,689	21	28
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income	1,432				82		82
Capital contributions from parent company					149	149
Other comprehensive income	38			38	10			10
Cash dividends on common stock	(765)		(765)		(146)		(146)
Other	(1)	(2)	2
Ending balance at Sep. 30, 2023	$ 35,304	$ 13,751	$ 12,391	$ (130)	$ 10,833	$ 10,838	$ (43)	$ 38

Introduction

Introduction	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Introduction	INTRODUCTION The condensed quarterly financial statements of each Registrant included herein have been prepared by such Registrant, without audit, pursuant to the rules and regulations of the SEC. The Condensed Balance Sheets at December 31, 2022 have been derived from the audited financial statements of each Registrant. In the opinion of each Registrant's management, the information regarding such Registrant furnished herein reflects all adjustments, which, except as otherwise disclosed, are of a normal recurring nature, necessary to present fairly the results of operations for the periods ended September 30, 2023 and 2022. Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations, although each Registrant believes that the disclosures regarding such Registrant are adequate to make the information presented not misleading. Disclosures which would substantially duplicate the disclosures in the Form 10-K and details which have not changed significantly in amount or composition since the filing of the Form 10-K are generally omitted from this Quarterly Report on Form 10-Q unless specifically required by GAAP. Therefore, these Condensed Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the Form 10-K. Due to the seasonal variations in the demand for energy and other factors, operating results for the periods presented are not necessarily indicative of the operating results to be expected for the full year. Certain prior year data presented in the financial statements have been reclassified to conform to the current year presentation. These reclassifications had no impact on the overall results of operations, financial position, or cash flows of any Registrant. Recently Adopted Accounting Standards In March 2020 and December 2022, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting and ASU 2022-06, Reference Rate Reform (Topic 848): Deferral of the Sunset Date of Topic 848 , respectively, providing temporary guidance to ease the potential burden in accounting for reference rate reform primarily resulting from the discontinuation of LIBOR through December 31, 2024. See Note 1 to the financial statements under "Recently Adopted Accounting Standards" in Item 8 of the Form 10-K for additional information on the temporary guidance. Certain provisions in PPAs at Southern Power include references to LIBOR. Contract amendments have been executed to change to a SOFR-based interest rate. Southern Power adopted and applied the practical expedients guidance to these PPAs. Additionally, the Registrants referenced LIBOR for certain debt and hedging arrangements. As of July 1, 2023, all of the debt and hedging arrangements of the Registrants have transitioned to a SOFR-based interest rate based on the terms of the agreements. There were no material impacts from the transition to SOFR and no impacts to any existing accounting conclusions. See Note (J) under "Interest Rate Derivatives" for additional information. Goodwill and Other Intangible Assets Goodwill at September 30, 2023 and December 31, 2022 was as follows: Goodwill (in millions) Southern Company $ 5,161 Southern Company Gas: Gas distribution operations $ 4,034 Gas marketing services 981 Southern Company Gas total $ 5,015 Goodwill is not amortized, but is subject to an annual impairment test during the fourth quarter of each year, or more frequently if goodwill impairment indicators arise. Other intangible assets were as follows: At September 30, 2023 At December 31, 2022 Gross Carrying Amount Accumulated Amortization Other Gross Carrying Amount Accumulated Amortization Other (in millions) (in millions) Southern Company Subject to amortization: Customer relationships $ 211 $ (169) $ 42 $ 212 $ (162) $ 50 Trade names 63 (50) 13 64 (44) 20 PPA fair value adjustments 390 (143) 247 390 (129) 261 Other 5 (5) — 5 (5) — Total subject to amortization $ 669 $ (367) $ 302 $ 671 $ (340) $ 331 Not subject to amortization: FCC licenses 75 — 75 75 — 75 Total other intangible assets $ 744 $ (367) $ 377 $ 746 $ (340) $ 406 Southern Power (*) PPA fair value adjustments $ 390 $ (143) $ 247 $ 390 $ (129) $ 261 Southern Company Gas (*) Gas marketing services Customer relationships $ 156 $ (143) $ 13 $ 156 $ (139) $ 17 Trade names 26 (20) 6 26 (17) 9 Total other intangible assets $ 182 $ (163) $ 19 $ 182 $ (156) $ 26 (*) All subject to amortization. Amortization associated with other intangible assets was as follows: Three Months Ended Nine Months Ended Three Months Ended Nine Months Ended September 30, 2023 September 30, 2022 (in millions) Southern Company (a) $ 10 $ 27 $ 11 $ 30 Southern Power (b) 5 14 5 15 Southern Company Gas 3 7 4 9 (a) Includes $5 million, $14 million, $5 million, and $15 million for the three and nine months ended September 30, 2023 and 2022, respectively, recorded as a reduction to operating revenues. (b) Recorded as a reduction to operating revenues. Cash, Cash Equivalents, and Restricted Cash The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the condensed balance sheets that total to the amount shown in the condensed statements of cash flows for the applicable Registrants: Southern Company Alabama Power Georgia Power Southern Power Southern (in millions) At September 30, 2023 Cash and cash equivalents $ 1,676 $ 621 $ 173 $ 236 $ 397 Restricted cash (a) : Other current assets 176 108 48 18 2 Other deferred charges and assets 38 — 35 3 — Total cash, cash equivalents, and restricted cash (b) $ 1,890 $ 729 $ 256 $ 257 $ 399 At December 31, 2022 Cash and cash equivalents $ 1,917 $ 687 $ 364 $ 131 $ 81 Restricted cash (a) : Other current assets 62 — 60 — 2 Other deferred charges and assets 58 — 56 3 — Total cash, cash equivalents, and restricted cash (b) $ 2,037 $ 687 $ 480 $ 133 $ 83 (a) For Alabama Power, balance at September 30, 2023 reflects proceeds from the issuance of solid waste disposal facility revenue bonds in 2023. For Georgia Power, reflects proceeds from the issuance of solid waste disposal facility revenue bonds in 2022. For Southern Power, reflects $18 million at September 30, 2023 resulting from an arbitration interim award held to fund future replacement costs and $3 million at both September 30, 2023 and December 31, 2022 held to fund estimated construction completion costs at the Deuel Harvest wind facility. See Note (C) under "General Litigation Matters – Southern Power" for additional information. For Southern Company Gas, reflects collateral for workers' compensation, life insurance, and long-term disability insurance. (b) Total may not add due to rounding. Natural Gas for Sale With the exception of Nicor Gas, Southern Company Gas records natural gas inventories on a WACOG basis. For any declines in market prices below the WACOG considered to be other than temporary, an adjustment is recorded to reduce the value of natural gas inventories to market value. Nicor Gas' natural gas inventory is carried at cost on a LIFO basis. Inventory decrements occurring during the year that are restored prior to year-end are charged to cost of natural gas at the estimated annual replacement cost. Inventory decrements that are not restored prior to year-end are charged to cost of natural gas at the actual LIFO cost of the inventory layers liquidated. Southern Company Gas recorded no material adjustments to natural gas inventories for either period presented. Nicor Gas' inventory decrement at September 30, 2023 is expected to be restored prior to year-end. Storm Damage Reserves See Note 1 to the financial statements in Item 8 of the Form 10-K under "Storm Damage and Reliability Reserves" for additional information. Storm damage reserve activity for the traditional electric operating companies during the nine months ended September 30, 2023 was as follows: Southern Company (*) Alabama Power Georgia Power (*) Mississippi (in millions) Balance at December 31, 2022 $ 216 $ 97 $ 83 $ 36 Accrual 42 9 24 9 Weather-related damages (242) (35) (204) (3) Balance at September 30, 2023 $ 16 $ 71 $ (97) $ 42 (*) See Note (B) under "Georgia Power – Storm Damage Recovery" for additional information. Asset Retirement Obligations See Note 6 to the financial statements in Item 8 of the Form 10-K for additional information. Following initial criticality on March 6, 2023, Georgia Power recorded AROs of approximately $90 million related to Plant Vogtle Unit 3. See Note (B) under "Georgia Power – Nuclear Construction" for additional information on Plant Vogtle Units 3 and 4. In September 2023, Georgia Power recorded a net decrease of approximately $175 million to its AROs related to the CCR Rule and the related state rule resulting from changes in estimates, including lower future inflation rates and the timing of closure activities. In June 2023, Alabama Power completed an updated decommissioning cost site study for Plant Farley. The estimated cost of decommissioning based on the study resulted in a decrease in Alabama Power's ARO liability of approximately $15 million. See "Nuclear Decommissioning" herein for additional information. Nuclear Decommissioning See Note 6 to the financial statements in Item 8 of the Form 10-K under "Nuclear Decommissioning" for additional information. Site study cost is the estimate to decommission a specific facility as of the site study year. The decommissioning cost estimates are based on removal of the plant from service and prompt dismantlement. The actual decommissioning costs may vary from these estimates because of changes in the assumed date of decommissioning, changes in NRC requirements, or changes in the assumptions used in making these estimates. The estimated costs of decommissioning Plant Farley based on Alabama Power's June 2023 site study are as follows: Plant Farley Decommissioning periods: Beginning year 2037 Completion year 2087 (in millions) Site study costs: Radiated structures $ 1,402 Spent fuel management 513 Non-radiated structures 133 Total site study costs $ 2,048 For ratemaking purposes, Alabama Power's decommissioning costs are based on the site study. Significant assumptions used to determine these costs for ratemaking were an estimated inflation rate of 4.5% and an estimated trust earnings rate of 7.0%. Amounts previously contributed to the external trust funds are currently projected to be adequate to meet the updated decommissioning obligations. Alabama Power's site-specific estimates of decommissioning costs for Plant Farley are updated every five years. The next site study for Alabama Power is expected to be completed in 2028. Projections of funds are reviewed with the Alabama PSC to ensure that, over time, the deposits and earnings of the funds in the external trust will provide adequate funding to cover the site-specific costs. If necessary, Alabama Power would seek the Alabama PSC's approval to address any changes in a manner consistent with NRC and other applicable requirements. Income Taxes In the third quarter 2023, Georgia Power started generating advanced nuclear PTCs for Plant Vogtle Unit 3 beginning on the in-service date of July 31, 2023. PTCs are recognized as an income tax benefit based on KWH production. In addition, pursuant to the Global Amendments to the Vogtle Joint Ownership Agreements (as defined in Note (B) under "Georgia Power – Nuclear Construction – Joint Owner Contracts"), Georgia Power is purchasing advanced nuclear PTCs for Plant Vogtle Unit 3 from certain other Vogtle Owners. The gain recognized on the purchase of the joint owner PTCs is recognized as an income tax benefit. See Note 1 to the financial statements under "Income Taxes" in Item 8 of the Form 10-K for additional information regarding accounting policies related to income taxes. See Note (B) under "Georgia Power – Nuclear Construction" for additional information regarding Plant Vogtle Units 3 and 4. Also see Note (G) under "Current and Deferred Income Taxes" for additional information.

Regulatory Matters

Regulatory Matters	9 Months Ended
	Sep. 30, 2023
Regulated Operations [Abstract]
Regulatory Matters	REGULATORY MATTERS See Note 2 to the financial statements in Item 8 of the Form 10-K for additional information relating to regulatory matters. The recovery balances for certain retail regulatory clauses of the traditional electric operating companies and Southern Company Gas at September 30, 2023 and December 31, 2022 were as follows: Regulatory Clause Balance Sheet Line Item September 30, December 31, 2022 (in millions) Alabama Power Rate CNP Compliance Other regulatory liabilities, deferred $ 3 $ — Other regulatory assets, current — 47 Rate CNP PPA Other regulatory assets, current 17 18 Other regulatory assets, deferred 90 102 Retail Energy Cost Recovery Other regulatory assets, current 208 102 Other regulatory assets, deferred 80 520 Georgia Power Fuel Cost Recovery (*) Receivables – under recovered fuel clause revenues $ 730 $ — Deferred under recovered fuel clause revenues 1,279 2,056 Mississippi Power Fuel Cost Recovery Receivables – customer accounts, net $ 25 $ 1 Ad Valorem Tax Other regulatory assets, current 3 12 Other regulatory assets, deferred 11 19 Southern Company Gas Natural Gas Cost Recovery Natural gas cost under recovery $ — $ 108 Natural gas cost over recovery 165 — (*) See "Georgia Power – Fuel Cost Recovery" herein for additional information. Alabama Power Certificates of Convenience and Necessity In 2020, the Alabama PSC approved a certificate of convenience and necessity authorizing Alabama Power's construction of Plant Barry Unit 8 and the recovery of estimated in-service costs of $652 million. At September 30, 2023, project expenditures associated with Plant Barry Unit 8 totaled approximately $583 million, of which $578 million and $5 million was included in CWIP and property, plant, and equipment in service, respectively. On November 1, 2023, the unit was placed in service. The ultimate outcome of this matter cannot be determined at this time. Excess Accumulated Deferred Income Tax Accounting Order On October 3, 2023, the Alabama PSC issued an order modifying its December 2022 order and authorizing Alabama Power to (i) flow back in 2023 approximately $24 million of certain federal excess accumulated deferred income taxes resulting from the Tax Cuts and Jobs Act of 2017 and (ii) make available any remaining balance of excess accumulated deferred income taxes at the end of 2023 for the benefit of customers in 2024 and/or 2025. The ultimate outcome of this matter cannot be determined at this time. Rate CNP New Plant On March 24, 2023, Alabama Power filed Rate CNP New Plant with the Alabama PSC to recover costs associated with the acquisition of the Central Alabama Generating Station. The filing reflected an annual increase in retail revenues of $78 million effective with June 2023 billings. Through May 2023, Alabama Power recovered substantially all costs associated with the Central Alabama Generating Station through Rate RSE, offset by revenues from a power sales agreement. On May 24, 2023, the Central Alabama Generating Station was placed into retail service. See Note 15 to the financial statements under "Alabama Power" in Item 8 of the Form 10-K for additional information. Renewable Generation Certificate Through the issuance of a Renewable Generation Certificate (RGC), Alabama Power is authorized by the Alabama PSC to procure renewable capacity and energy and to market the related energy and environmental attributes to customers and other third parties. On April 4, 2023, the Alabama PSC approved two new solar PPAs totaling 160 MWs. Upon approval of these PPAs, Alabama Power had procured solar capacity totaling approximately 490 MWs under the RGC's original 500-MW limit. On June 14, 2023, the Alabama PSC issued an order approving modifications to Alabama Power's RGC. The modifications authorized Alabama Power to procure an additional 2,400 MWs of renewable capacity and energy by June 14, 2029 and to market the related energy and environmental attributes to customers and other third parties. The modifications also increased the size of allowable renewable projects from 80 MWs to 200 MWs and increased the annual approval limit from 160 MWs to 400 MWs. Reliability Reserve Accounting Order On July 11, 2023, the Alabama PSC issued an order authorizing Alabama Power to expand the existing authority of its reliability reserve to include certain production-related expenses that are intended to maintain reliability in between scheduled generating unit maintenance outages. On August 18, 2023, Alabama Power notified the Alabama PSC of its intent to use a portion of its $166 million reliability reserve balance during 2023. The ultimate outcome of this matter cannot be determined at this time. Georgia Power Rate Plans In accordance with the terms of the 2022 ARP, on October 2, 2023, Georgia Power filed the following tariff adjustments to become effective January 1, 2024 pending approval by the Georgia PSC: • increase traditional base tariffs by approximately $275 million; • decrease the Environmental Compliance Cost Recovery tariff by approximately $99 million; • increase the Demand-Side Management tariffs by approximately $10 million; and • increase the Municipal Franchise Fee tariffs by approximately $5 million. The ultimate outcome of this matter cannot be determined at this time. Plant Vogtle Unit 3 and Common Facilities Rate Proceeding In compliance with a Georgia PSC order approved in November 2021, Georgia Power increased annual retail base rates by $318 million effective August 1, 2023 based on the in-service date of July 31, 2023 for Plant Vogtle Unit 3. See "Plant Vogtle Units 3 and 4 Prudency Proceeding" and "Nuclear Construction" herein for additional information on Plant Vogtle Units 3 and 4. Plant Vogtle Units 3 and 4 Prudency Proceeding On August 30, 2023, as provided for in the December 2017 Georgia PSC approval of the seventeenth VCM report, Georgia Power filed with the Georgia PSC an application to adjust rates to include reasonable and prudent Plant Vogtle Units 3 and 4 costs (Application). The Application provides the necessary support to justify the reasonableness, prudence, and recovery of $8.826 billion in total construction and capital costs, $1.07 billion in associated retail rate base items, and the operating costs related to the full operation and output of Plant Vogtle Units 3 and 4. Through the VCM process, the Georgia PSC has verified and approved all expenditures up to the revised approved construction and capital cost of $7.3 billion and has reviewed, but not verified and approved, all expenditures through December 31, 2022 above that amount. Also on August 30, 2023, the staff of the Georgia PSC filed a stipulated agreement (Prudency Stipulation) among Georgia Power, the staff of the Georgia PSC, and certain intervenors. The Prudency Stipulation is intended to resolve all issues for determination by the Georgia PSC regarding the reasonableness, prudence, and cost recovery for the remaining costs not already in retail base rates, after considering many of the issues raised by the staff of the Georgia PSC and intervenors in prior VCM proceedings, including the extended construction time, required rework, scheduling of activities, and challenges with testing and productivity. If the Prudency Stipulation is approved, Georgia Power will recover $7.562 billion in total construction and capital costs and associated retail rate base items of $1.02 billion, which includes AFUDC financing costs above $4.418 billion (the Georgia PSC-certified amount) up to $7.562 billion. The Prudency Stipulation also provides for the recovery of projected operations and maintenance expenses, depreciation expense, nuclear decommissioning accruals, and property taxes, net of projected production tax credits. After considering construction and capital costs already in retail base rates of $2.1 billion and $362 million of associated retail rate base items (approved by the Georgia PSC in November 2021), and upon achieving commercial operation of Unit 4, Georgia Power will include in retail rate base the remaining $5.462 billion of construction and capital costs as well as $656 million of associated retail rate base items. Under the terms of the Prudency Stipulation, when the rate adjustment occurs, Georgia Power's NCCR tariff will cease to be collected and financing costs will be included in Georgia Power's general revenue requirements. Additionally, if commercial operation for Unit 4 is not achieved by March 31, 2024, Georgia Power's ROE used to determine the NCCR tariff and calculate AFUDC will be reduced to zero, which would result in an estimated negative impact to earnings of approximately $12 million per month until commercial operation for Unit 4 is achieved. The Prudency Stipulation also provides that as of each Unit's respective first refueling outage, if the respective Unit's performance has materially deviated from expected performance, the Georgia PSC may order Georgia Power to credit customers for operations and maintenance expenses or disallow costs associated with the repair or replacement of any system, structure, or component found to have caused the material deviation in performance if proven to be the result of imprudent engineering, construction, procurement, testing, or start-up. If the Prudency Stipulation is approved by the Georgia PSC, annual retail base revenues will increase approximately $729 million and the average retail base rates will be adjusted by approximately 5% (net of the elimination of the NCCR tariff described above) effective the first day of the month after Unit 4 achieves commercial operation. Georgia Power expects the Georgia PSC to render a final decision on these matters on December 19, 2023. The ultimate outcome of these matters cannot be determined at this time. See "Plant Vogtle Unit 3 and Common Facilities Rate Proceeding" and "Nuclear Construction" herein for additional information on Plant Vogtle Units 3 and 4. Fuel Cost Recovery On May 16, 2023, the Georgia PSC approved a stipulation agreement between Georgia Power and the staff of the Georgia PSC to increase annual fuel billings by 54%, or approximately $1.1 billion, effective June 1, 2023. The increase includes a three-year recovery period for $2.2 billion of Georgia Power's under recovered fuel balance at May 31, 2023. Under the approved stipulation agreement, Georgia Power is allowed to adjust its fuel cost recovery rates under an interim fuel rider prior to the next fuel case, subject to a maximum 40% cumulative change, if its under or over recovered fuel balance accumulated since May 31, 2023 exceeds $200 million. Georgia Power is scheduled to file its next fuel case no later than February 28, 2026. Changes in fuel rates have no significant effect on Southern Company's or Georgia Power's net income but do impact the related operating cash flows. Integrated Resource Plans In August 2022, Restore Chattooga Gorge Coalition (RCG) filed a petition in the Superior Court of Fulton County, Georgia against Georgia Power and the Georgia PSC. The petition challenges Georgia Power's plan to expend $115 million to modernize Plant Tugalo (a hydro facility), as approved in the 2019 IRP, and seeks judicial review of the Georgia PSC's order in the 2022 IRP proceeding with respect to the denial of RCG's challenge to the modernization plan. On October 23, 2023, the court granted Georgia Power's and the Georgia PSC's motions to dismiss the RCG petition. RCG has until November 22, 2023 to file a notice of appeal. On October 27, 2023, Georgia Power filed an updated IRP (2023 IRP Update) with the Georgia PSC, which sets forth a plan to support the recent increase in the state of Georgia's projected energy needs since the 2022 IRP. In the 2023 IRP Update, Georgia Power requested the following: • Authority to develop, own, and operate up to 1,400 MWs from three simple cycle combustion turbines at Plant Yates. • Approval to pursue potential acquisition of an additional ownership interest in an existing generation asset within the Southern Company system's retail electric service territory. • Certification of an affiliate PPA with Mississippi Power for 750 MWs starting January 2024 through December 2028. • Certification of a non-affiliate PPA for 230 MWs starting the month after conclusion of the 2023 IRP Update proceeding continuing through December 2028. • Authority to develop, own, and operate up to 1,000 MWs of battery energy storage facilities collocated with existing and new Georgia Power-owned solar facilities. • Approval of transmission projects necessary to support the generation resources requested in the 2023 IRP Update. The schedule for the Georgia PSC to consider the 2023 IRP Update has not been determined. Georgia Power has requested that the Georgia PSC evaluate the 2023 IRP Update by the end of April 2024. The ultimate outcome of these matters cannot be determined at this time. Storm Damage Recovery Georgia Power is recovering $31 million annually under the 2022 ARP for incremental operating and maintenance costs of damage from major storms to its transmission and distribution facilities. During August 2023, Hurricane Idalia caused significant damage to Georgia Power's transmission and distribution facilities. The incremental restoration costs related to this hurricane deferred in the regulatory asset for storm damage totaled approximately $110 million. At September 30, 2023, Georgia Power's regulatory asset balance related to storm damage was $97 million. The rate of storm damage cost recovery is expected to be adjusted in future regulatory proceedings as necessary. As a result of this regulatory treatment, costs related to storms are not expected to have a material impact on Southern Company's or Georgia Power's net income but do impact the related operating cash flows. Nuclear Construction In 2009, the Georgia PSC certified construction of Plant Vogtle Units 3 and 4, in which Georgia Power holds a 45.7% ownership interest. In 2012, the NRC issued the related combined construction and operating licenses, which allowed full construction of the two AP1000 nuclear units (with electric generating capacity of approximately 1,100 MWs each) and related facilities to begin. Until March 2017, construction on Plant Vogtle Units 3 and 4 continued under the Vogtle 3 and 4 Agreement, which was a substantially fixed price agreement. In connection with the EPC Contractor's bankruptcy filing in March 2017, Georgia Power, acting for itself and as agent for the other Vogtle Owners, entered into several transitional arrangements to allow construction to continue. In July 2017, Georgia Power, acting for itself and as agent for the other Vogtle Owners, entered into the Vogtle Services Agreement, whereby Westinghouse provides facility design and engineering services, procurement and technical support, and staff augmentation on a time and materials cost basis. The Vogtle Services Agreement provides that it will continue until the start-up and testing of Plant Vogtle Units 3 and 4 are complete and electricity is generated and sold from both units. The Vogtle Services Agreement is terminable by the Vogtle Owners upon 30 days' written notice. In October 2017, Georgia Power, acting for itself and as agent for the other Vogtle Owners, executed the Bechtel Agreement, under which Bechtel is reimbursed for actual costs plus a base fee and an at-risk fee, subject to adjustment based on Bechtel's performance against cost and schedule targets. Each Vogtle Owner is severally (not jointly) liable for its proportionate share, based on its ownership interest, of all amounts owed to Bechtel under the Bechtel Agreement. The Vogtle Owners may terminate the Bechtel Agreement at any time for their convenience, provided that the Vogtle Owners will be required to pay amounts related to work performed prior to the termination (including the applicable portion of the base fee), certain termination-related costs, and, at certain stages of the work, the applicable portion of the at-risk fee. Bechtel may terminate the Bechtel Agreement under certain circumstances, including certain Vogtle Owner suspensions of work, certain breaches of the Bechtel Agreement by the Vogtle Owners, Vogtle Owner insolvency, and certain other events. See Note 8 to the financial statements under "Long-term Debt – DOE Loan Guarantee Borrowings" in Item 8 of the Form 10-K for information on the Amended and Restated Loan Guarantee Agreement, including applicable covenants, events of default, and mandatory prepayment events. Cost and Schedule Georgia Power's approximate proportionate share of the remaining estimated capital cost to complete Plant Vogtle Units 3 and 4, including contingency, through July 2023 and March 2024, respectively, is as follows: (in millions) Base project capital cost forecast (a)(b) $ 10,736 Construction contingency estimate 17 Total project capital cost forecast (a)(b) 10,753 Net investment at September 30, 2023 (b) (10,495) Remaining estimate to complete $ 258 (a) Includes approximately $610 million of costs that are not shared with the other Vogtle Owners, including $33 million of construction monitoring costs approved for recovery by the Georgia PSC in its nineteenth VCM order, and approximately $567 million of incremental costs under the cost-sharing provisions of the joint ownership agreements described below. Excludes financing costs expected to be capitalized through AFUDC of approximately $420 million, of which $385 million had been accrued through September 30, 2023. (b) Net of $1.7 billion received from Toshiba under the Guarantee Settlement Agreement and approximately $188 million in related customer refunds. Georgia Power estimates that its financing costs for construction of Plant Vogtle Units 3 and 4 will total approximately $3.5 billion, of which $3.4 billion had been incurred through September 30, 2023. Georgia Power placed Unit 3 in service on July 31, 2023. See "Plant Vogtle Unit 3 and Common Facilities Rate Proceeding" herein for additional information. As part of its ongoing processes, Southern Nuclear continues to evaluate cost and schedule forecasts for Unit 4 on a regular basis to incorporate current information available, particularly in the areas of start-up testing and related test results, engineering support, system turnovers, and workforce statistics. Southern Nuclear establishes aggressive target values for monthly testing and system turnover activities, which are reflected in the site work plan for Unit 4. Since March 2020, the number of active COVID-19 cases at the site has fluctuated consistent with the surrounding area and impacted productivity levels and pace of activity completion, with the site experiencing peaks in the number of active cases in January 2021, August 2021, and January 2022. Georgia Power estimates the productivity impacts of the COVID-19 pandemic have consumed approximately three During the first nine months of 2023, established construction contingency totaling $43 million was assigned to the base capital cost forecast for costs primarily associated with the Unit 3 schedule extension and completion of start-up and pre-operational testing, including continued need of support resources for Unit 3 testing, as well as additional craft and support resources and subcontract work for Unit 4. Hot functional testing for Unit 4 was completed on May 1, 2023. On July 20, 2023, Southern Nuclear announced that all Unit 4 ITAACs had been submitted to the NRC, and, on July 28, 2023, the NRC published its 103(g) finding that the accepted criteria in the combined license for Unit 4 had been met, which allowed nuclear fuel to be loaded and start-up testing to begin. Fuel load for Unit 4 was completed on August 19, 2023. On October 6, 2023, Georgia Power announced that during the start-up and pre-operational testing for Plant Vogtle Unit 4, Southern Nuclear identified a motor fault in one of four reactor coolant pumps (RCPs) and has started the process to replace this RCP with an on-site spare RCP from inventory. Considering this remediation and the remaining pre-operational testing, Unit 4 is projected to be placed in service during the first quarter 2024. With Unit 3's four RCPs operating as designed, Southern Nuclear believes that the motor fault on this single Unit 4 RCP is an isolated event. However, any findings related to the root cause of the motor fault on the single Unit 4 RCP could require engineering changes or remediation related to the other seven Unit 3 and Unit 4 RCPs. The projected schedule for Unit 4 significantly depends on the pace and success of replacing the RCP, which involves removing and re-installing commodities around the RCP. As Unit 4 completes the RCP replacement, including any associated repairs to other RCPs, and transitions further into testing, ongoing and potential future challenges include the management of contractors and vendors, subcontractor performance, the availability of materials and parts, and/or related cost escalation; the pace of remaining work package closures; the availability of craft, supervisory, and technical support resources; and the timeframe and duration of final component and pre-operational testing. New challenges also may continue to arise as Unit 4 moves further into testing and start-up, which may result in required engineering changes or remediation related to plant systems, structures, or components (some of which are based on new technology that only within the last few years began initial operation in the global nuclear industry at this scale). These challenges may result in further schedule delays and/or cost increases. There have been technical and procedural challenges to the construction and licensing of Plant Vogtle Units 3 and 4 at the federal and state level and additional challenges may arise. Processes are in place that are designed to ensure compliance with the requirements specified in the Westinghouse Design Control Document and the combined construction and operating licenses, including inspections by Southern Nuclear and the NRC that occur throughout construction. With the receipt of the NRC's 103(g) findings for Units 3 and 4 in August 2022 and July 2023, respectively, the site is subject to the NRC's operating reactor oversight process and must meet applicable technical and operational requirements contained in its operating license. Various design and other licensing-based compliance matters may result in additional license amendment requests or require other resolution. If any license amendment requests or other licensing-based compliance issues are not resolved in a timely manner, there may be delays in the Unit 4 project schedule that could result in increased costs. The ultimate outcome of these matters cannot be determined at this time. However, any extension of the in-service date beyond March 2024 for Unit 4, including the joint owner cost sharing impacts described below, is estimated to result in additional base capital costs for Georgia Power of up to $25 million per month, as well as the related AFUDC and any additional related construction, support resources, or testing costs. Pursuant to Georgia Power's Application and the Prudency Stipulation (as discussed under "Plant Vogtle Units 3 and 4 Prudency Proceeding" herein), any further changes to the capital cost forecast are not expected to be recoverable through regulated rates and will be required to be charged to income. Such charges could be material. Joint Owner Contracts In November 2017, the Vogtle Owners entered into an amendment to their joint ownership agreements for Plant Vogtle Units 3 and 4 to provide for, among other conditions, additional Vogtle Owner approval requirements. Effective in August 2018, the Vogtle Owners further amended the joint ownership agreements to clarify and provide procedures for certain provisions of the joint ownership agreements related to adverse events that require the vote of the holders of at least 90% of the ownership interests in Plant Vogtle Units 3 and 4 to continue construction (as amended, and together with the November 2017 amendment, the Vogtle Joint Ownership Agreements). The Vogtle Joint Ownership Agreements also confirm that the Vogtle Owners' sole recourse against Georgia Power or Southern Nuclear for any action or inaction in connection with their performance as agent for the Vogtle Owners is limited to removal of Georgia Power and/or Southern Nuclear as agent, except in cases of willful misconduct. Amendments to the Vogtle Joint Ownership Agreements In connection with a September 2018 vote by the Vogtle Owners to continue construction, Georgia Power entered into (i) a binding term sheet (Vogtle Owner Term Sheet) with the other Vogtle Owners and MEAG Power's wholly-owned subsidiaries MEAG Power SPVJ, LLC (MEAG SPVJ), MEAG Power SPVM, LLC (MEAG SPVM), and MEAG Power SPVP, LLC (MEAG SPVP) to take certain actions which partially mitigate potential financial exposure for the other Vogtle Owners, including additional amendments to the Vogtle Joint Ownership Agreements and the purchase of PTCs from the other Vogtle Owners at pre-established prices, and (ii) a term sheet (MEAG Term Sheet) with MEAG Power and MEAG SPVJ to provide up to $300 million of funding with respect to MEAG SPVJ's ownership interest in Plant Vogtle Units 3 and 4 under certain circumstances. In January 2019, Georgia Power, MEAG Power, and MEAG SPVJ entered into an agreement to implement the provisions of the MEAG Term Sheet. In February 2019, Georgia Power, the other Vogtle Owners, and MEAG Power's wholly-owned subsidiaries MEAG SPVJ, MEAG SPVM, and MEAG SPVP entered into certain amendments to the Vogtle Joint Ownership Agreements to implement the provisions of the Vogtle Owner Term Sheet (Global Amendments). Pursuant to the Global Amendments: (i) each Vogtle Owner paid its proportionate share of qualifying construction costs for Plant Vogtle Units 3 and 4 based on its ownership percentage up to the estimated cost at completion (EAC) for Plant Vogtle Units 3 and 4, of which Georgia Power's share is $8.4 billion (VCM 19 Forecast Amount), plus $800 million; (ii) Georgia Power was responsible for 55.7% of actual qualifying construction costs between $800 million and $1.6 billion over the VCM 19 Forecast Amount (resulting in $80 million of potential additional costs to Georgia Power), with the remaining Vogtle Owners responsible for 44.3% of such costs pro rata in accordance with their respective ownership interests; and (iii) Georgia Power was responsible for 65.7% of qualifying construction costs between $1.6 billion and $2.1 billion over the VCM 19 Forecast Amount (resulting in a further $100 million of potential additional costs to Georgia Power), with the remaining Vogtle Owners responsible for 34.3% of such costs pro rata in accordance with their respective ownership interests. The Global Amendments provide that if the EAC was revised and exceeded the VCM 19 Forecast Amount by more than $2.1 billion, each of the other Vogtle Owners had a one-time option at the time the project budget cost forecast was so revised to tender a portion of its ownership interest to Georgia Power in exchange for Georgia Power's agreement to pay 100% of such Vogtle Owner's remaining share of total construction costs in excess of the VCM 19 Forecast Amount plus $2.1 billion. In addition, pursuant to the Global Amendments, the holders of at least 90% of the ownership interests in Plant Vogtle Units 3 and 4 must vote to continue construction if certain adverse events (Project Adverse Events) occur, including, among other events: (i) the bankruptcy of Toshiba; (ii) the termination or rejection in bankruptcy of certain agreements, including the Vogtle Services Agreement, the Bechtel Agreement, or the agency agreement with Southern Nuclear; (iii) Georgia Power's public announcement of its intention not to submit for rate recovery any portion of its investment in Plant Vogtle Units 3 and 4 or the Georgia PSC determines that any of Georgia Power's costs relating to the construction of Plant Vogtle Units 3 and 4 will not be recovered in retail rates, excluding any additional amounts paid by Georgia Power on behalf of the other Vogtle Owners pursuant to the Global Amendments described above and the first 6% of costs during any six-month VCM reporting period that are disallowed by the Georgia PSC for recovery, or for which Georgia Power elects not to seek cost recovery, through retail rates; and (iv) an incremental extension of one year or more from the seventeenth VCM report estimated in- service dates of November 2021 and November 2022 for Units 3 and 4, respectively. The schedule extension announced in February 2022 triggered the requirement for a vote to continue construction and all the Vogtle Owners voted to continue construction. The filing of the Application with the Georgia PSC, which included Georgia Power's public announcement of its intention not to submit for rate recovery an amount that is greater than the first 6% of costs during any six-month VCM reporting period, triggered the requirement for a vote to continue construction and all the Vogtle Owners voted to continue construction. See "Plant Vogtle Units 3 and 4 Prudency Proceeding" herein for additional information on Georgia Power's prudency application filing. Georgia Power and the other Vogtle Owners did not agree on either the starting dollar amount for the determination of cost increases subject to the cost-sharing and tender provisions of the Global Amendments or the extent to which COVID-19-related costs impact those provisions. The other Vogtle Owners notified Georgia Power that they believed the project capital cost forecast approved by the Vogtle Owners in February 2022 triggered the tender provisions. In June 2022 and July 2022, OPC and Dalton, respectively, notified Georgia Power of their purported exercises of their tender options. Georgia Power did not accept these purported tender exercises. In June 2022, OPC and MEAG Power each filed a separate lawsuit against Georgia Power in the Superior Court of Fulton County, Georgia seeking a declaratory judgment that the starting dollar amount is $17.1 billion and that the cost-sharing and tender provisions had been triggered. The lawsuits also assert other claims, including breach of contract allegations, and seek, among other remedies, damages and injunctive relief requiring Georgia Power to track and allocate construction costs consistent with MEAG Power's and OPC's interpretations of the Global Amendments. In July 2022, Georgia Power filed its answers in the lawsuits filed by MEAG Power and OPC and included counterclaims seeking a declaratory judgment that the starting dollar amount is $18.38 billion and that costs related to force majeure events are excluded prior to calculating the cost-sharing and tender provisions and when calculating Georgia Power's related financial obligations. In September 2022, Dalton filed complaints in each of these lawsuits. Also in September 2022, Georgia Power and MEAG Power reached an agreement to resolve their dispute regarding the proper interpretation of the cost-sharing and tender provisions of the Global Amendments. Under the terms of the agreement, among other items, (i) MEAG Power will not exercise its tender option and will retain its full ownership interest in Plant Vogtle Units 3 and 4; (ii) Georgia Power will reimburse a portion of MEAG Power's costs of construction for Plant Vogtle Units 3 and 4 as such costs are incurred and with no further adjustment for force majeure costs, which payments will total approximately $92 million based on the current project capital cost forecast; and (iii) Georgia Power will reimburse 20% of MEAG Power's costs of construction with respect to any amounts over the current project capital cost forecast, with no further adjustment for force majeure costs. In addition, MEAG Power agreed to vote to continue construction upon occurrence of a Project Adverse Event unless the commercial operation date of either of Plant Vogtle Unit 3 or Unit 4 is not projected to occur by December 31, 2025. In October 2022, MEAG Power and Georgia Power filed a notice of settlement and voluntary dismissal of their pending litigation, including Georgia Power's counterclaim, and Dalton dismissed its related complaint. On October 5, 2023 and October 17, 2023, Georgia Power reached agreements with OPC and Dalton, respectively, to resolve its respective dispute with each of OPC and Dalton regarding the proper interpretation of the cost-sharing and tender provisions of the joint ownership agreements relating to the Global Amendments. Und

Contingencies

Contingencies	9 Months Ended
	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Contingencies	CONTINGENCIESSee Note 3 to the financial statements in Item 8 of the Form 10-K for information relating to various lawsuits and other contingencies. General Litigation Matters The Registrants are involved in various matters being litigated and regulatory matters. The ultimate outcome of such pending or potential litigation or regulatory matters against each Registrant and any subsidiaries cannot be determined at this time; however, for current proceedings not specifically reported herein, management does not anticipate that the ultimate liabilities, if any, arising from such current proceedings would have a material effect on such Registrant's financial statements. The Registrants believe the pending legal challenges discussed below have no merit; however, the ultimate outcome of these matters cannot be determined at this time. Southern Company and Mississippi Power In 2010, the DOE, through a cooperative agreement with SCS, agreed to fund $270 million of the Kemper County energy facility through the grants awarded to the project by the DOE under the Clean Coal Power Initiative Round 2. In 2016, additional DOE grants in the amount of $137 million were awarded to the Kemper County energy facility. In 2018, Mississippi Power filed with the DOE its request for property closeout certification under the contract related to the $387 million of total grants received. In 2020, Mississippi Power and Southern Company executed an agreement with the DOE completing Mississippi Power's request, which enabled Mississippi Power to proceed with full dismantlement of the abandoned gasifier-related assets and site restoration activities. In connection with the DOE closeout discussions, in 2019, the Civil Division of the Department of Justice informed Southern Company and Mississippi Power of a civil investigation related to the DOE grants. On August 4, 2023, the U.S. District Court for the Northern District of Georgia unsealed a civil action in which defendants Southern Company, SCS, and Mississippi Power are alleged to have violated certain provisions of the False Claims Act by fraudulently inducing the DOE to disburse funds pursuant to the grants. The federal government declined to intervene in the action. On October 30, 2023, the plaintiff, a former SCS employee, filed an amended complaint, again alleging certain violations of the False Claims Act. The plaintiff seeks to recover all damages incurred personally and on behalf of the government caused by the defendants' alleged violations, as well as treble damages and attorneys' fees, among other relief. The ultimate outcome of this matter cannot be determined at this time; however, an adverse outcome could have a material impact on Southern Company's and Mississippi Power's financial statements. Alabama Power In September 2022, Mobile Baykeeper filed a citizen suit in the U.S. District Court for the Southern District of Alabama alleging that Alabama Power's plan to close the Plant Barry ash pond utilizing a closure-in-place methodology violates the Resource Conservation and Recovery Act (RCRA) and regulations governing CCR. Among other relief requested, Mobile Baykeeper seeks a declaratory judgment that the RCRA and regulations governing CCR are being violated, preliminary and injunctive relief to prevent implementation of Alabama Power's closure plan and the development of a closure plan that satisfies regulations governing CCR requirements. On December 19, 2022, Alabama Power filed a motion to dismiss the case. On September 30, 2023, the magistrate judge issued a report and recommendation to deny Alabama Power's motion to dismiss, to which Alabama Power has filed objections. On January 31, 2023, the EPA issued a Notice of Potential Violations associated with Alabama Power's plan to close the Plant Barry ash pond. Ala bama Power has affirmed to the EPA its position that it is in compliance with CCR requirements. The ultimate outcome of these matters cannot be determined at this time but could have a material impact on Alabama Power's ARO estimates and cash flows. See Note 6 to the financial statements in Item 8 of the Form 10-K for a discussion of Alabama Power's ARO liabilities. Georgia Power Municipal Franchise Fees In 2011, plaintiffs filed a putative class action against Georgia Power in the Superior Court of Fulton County, Georgia alleging that Georgia Power's collection in rates of amounts for municipal franchise fees (which fees are paid to municipalities) exceeded the amounts allowed in orders of the Georgia PSC and alleging certain state law claims. This case has been ruled upon and appealed numerous times over the last several years. In 2019, the Georgia PSC issued an order that found Georgia Power has appropriately implemented the municipal franchise fee schedule. In March 2021, the Superior Court of Fulton County granted class certification and Georgia Power's motion for summary judgment and the plaintiffs filed a notice of appeal. In April 2021, Georgia Power filed a notice of cross appeal on the issue of class certification. In December 2021, the Georgia Court of Appeals affirmed the Superior Court's ruling that granted summary judgment to Georgia Power and dismissed Georgia Power's cross appeal on the issue of class certification as moot. Also in December 2021, the plaintiffs filed a petition for writ of certiorari to the Georgia Supreme Court, which was denied on January 27, 2023. On February 6, 2023, the plaintiffs filed a motion for reconsideration with the Georgia Supreme Court, which was denied on February 16, 2023. This matter is now concluded. Plant Scherer In July 2020, a group of individual plaintiffs filed a complaint, which was amended in December 2022, in the Superior Court of Fulton County, Georgia against Georgia Power alleging that the construction and operation of Plant Scherer has impacted groundwater and air, resulting in alleged personal injuries and property damage. The plaintiffs seek an unspecified amount of monetary damages including punitive damages, a medical monitoring fund, and injunctive relief. In December 2022, the Superior Court of Fulton County, Georgia granted Georgia Power's motion to transfer the case to the Superior Court of Monroe County, Georgia. On May 9, 2023, the Superior Court of Monroe County, Georgia denied Georgia Power's motion to dismiss the case for lack of subject matter jurisdiction. On July 27, 2023, the Superior Court of Monroe County, Georgia denied the remaining motions to dismiss certain claims and plaintiffs that Georgia Power filed at the outset of the case. In October 2021, February 2022, and January 2023, a total of eight additional complaints were filed in the Superior Court of Monroe County, Georgia against Georgia Power alleging that releases from Plant Scherer have impacted groundwater and air, resulting in alleged personal injuries and property damage. The plaintiffs sought an unspecified amount of monetary damages including punitive damages. After Georgia Power removed these cases to the U.S. District Court for the Middle District of Georgia, the plaintiffs voluntarily dismissed their complaints without prejudice in November 2022 and January 2023. On May 12, 2023, the plaintiffs in the cases originally filed in October 2021, February 2022, and January 2023 refiled their eight complaints in the Superior Court of Monroe County, Georgia. Also on May 12, 2023, a new complaint was filed in the Superior Court of Monroe County, Georgia against Georgia Power alleging that the construction and operation of Plant Scherer have impacted groundwater and air, resulting in alleged personal injuries. The plaintiff seeks an unspecified amount of monetary damages, including punitive damages. On May 18, 2023, Georgia Power removed all of these cases to the U.S. District Court for the Middle District of Georgia. The plaintiffs are requesting the court remand the cases back to the Superior Court of Monroe County, Georgia. The amount of possible loss, if any, from these matters cannot be estimated at this time. Mississippi Power In 2018, Ray C. Turnage and 10 other individual plaintiffs filed a putative class action complaint against Mississippi Power and the three then-serving members of the Mississippi PSC in the U.S. District Court for the Southern District of Mississippi, which was amended in March 2019 to include four additional plaintiffs. Mississippi Power received Mississippi PSC approval in 2013 to charge a mirror CWIP rate premised upon including in its rate base pre-construction and construction costs for the Kemper IGCC prior to placing the Kemper IGCC into service. The Mississippi Supreme Court reversed that approval and ordered Mississippi Power to refund the amounts paid by customers under the previously-approved mirror CWIP rate. The plaintiffs allege that the initial approval process, and the amount approved, were improper and make claims for gross negligence, reckless conduct, and intentional wrongdoing. They also allege that Mississippi Power underpaid customers by up to $23.5 million in the refund process by applying an incorrect interest rate. The plaintiffs seek to recover, on behalf of themselves and their putative class, actual damages, punitive damages, pre-judgment interest, post-judgment interest, attorney's fees, and costs. The district court dismissed the amended complaint; however, in March 2020, the plaintiffs filed a motion seeking to name the new members of the Mississippi PSC, the Mississippi Development Authority, and Southern Company as additional defendants and add a cause of action against all defendants based on a dormant commerce clause theory under the U.S. Constitution. In July 2020, the plaintiffs filed a motion for leave to file a third amended complaint, which included the same federal claims as the proposed second amended complaint, as well as several additional state law claims based on the allegation that Mississippi Power failed to disclose the annual percentage rate of interest applicable to refunds. In November 2020, the district court denied each of the plaintiffs' pending Southern Power In July 2021, Southern Power and certain of its subsidiaries filed an arbitration demand with the American Arbitration Association against First Solar for defective design of actuators on trackers and inverters installed by First Solar under the engineering, procurement, and construction agreements associated with five solar projects owned by Southern Power and partners and managed by Southern Power. In February 2023, arbitration hearings concluded. In July 2023, an interim award of approximately $36 million was entered in favor of Southern Power and was subsequently received in September 2023. The interim award included $18 million representing recovery of losses associated with replacement costs, penalty payments, and lost revenues previously incurred. This recovery is reflected in Southern Power's third quarter and year-to-date 2023 statements of income as an $11 million reduction to other operations and maintenance expense and a $7 million increase in other revenues, with $6 million allocated through noncontrolling interests to Southern Power's partners. The remaining $18 million in award proceeds received in excess of the losses incurred is recognized on the balance sheet at September 30, 2023 as restricted cash and a liability to fund future replacement costs. The parties are awaiting issuance of a final award. The ultimate outcome of this matter cannot be determined at this time. Environmental Remediation The Southern Company system must comply with environmental laws and regulations governing the handling and disposal of waste and releases of hazardous substances. Under these various laws and regulations, the Southern Company system could incur substantial costs to clean up affected sites. The traditional electric operating companies and the natural gas distribution utilities in Illinois and Georgia have each received authority from their respective state PSCs or other applicable state regulatory agencies to recover approved environmental remediation costs through regulatory mechanisms. These regulatory mechanisms are adjusted annually or as necessary within limits approved by the state PSCs or other applicable state regulatory agencies. Georgia Power's environmental remediation liability was $14 million and $15 million at September 30, 2023 and December 31, 2022, respectively. Georgia Power has been designated or identified as a potentially responsible party at sites governed by the Georgia Hazardous Site Response Act and/or by the federal Comprehensive Environmental Response, Compensation, and Liability Act, and assessment and potential cleanup of such sites is expected. Southern Company Gas' environmental remediation liability was $234 million and $256 million at September 30, 2023 and December 31, 2022, respectively, based on the estimated cost of environmental investigation and remediation associated with known former manufactured gas plant operating sites. The ultimate outcome of these matters cannot be determined at this time; however, as a result of the regulatory treatment for environmental remediation expenses described above, the final disposition of these matters is not expected to have a material impact on the financial statements of the applicable Registrants. Other Matters Traditional Electric Operating Companies In April 2019, Bellsouth Telecommunications d/b/a AT&T Alabama (AT&T) filed a complaint against Alabama Power with the FCC alleging that the pole rental rate AT&T is required to pay pursuant to the parties' joint use agreement is unjust and unreasonable under federal law. The complaint sought a new rate and approximately $87 million in refunds of alleged overpayments for the preceding six years. In August 2019, the FCC stayed the case in favor of arbitration, which AT&T has not pursued. The ultimate outcome of this matter cannot be determined at this time, but an adverse outcome could have a material impact on the financial statements of Southern Company and Alabama Power. Georgia Power and Mississippi Power have joint use agreements with other AT&T affiliates. Mississippi Power In August 2022, the Mississippi Department of Revenue (Mississippi DOR) completed an audit of sales and use taxes paid by Mississippi Power from 2016 to 2019 and entered a final assessment, indicating a total amount due of $28 million, including associated penalties and interest. In October 2022, Mississippi Power filed an administrative appeal with the Mississippi DOR contesting the assessment. On October 2, 2023, Mississippi Power and the Mississippi DOR reached a settlement agreement on an assessment of approximately $11 million including associated penalties and interest, $7 million of which was previously paid by Mississippi Power. On October 5, 2023, Mississippi Power made a final $4 million payment and considers this matter closed. Pursuant to an accounting order approved by the Mississippi PSC in December 2022, Mississippi Power deferred $3 million of the agreed upon assessment related to taxes and associated interest to a regulatory asset for disposition in a future rate proceeding.

Revenue from Contracts with Cus

Revenue from Contracts with Customers and Lease Income	9 Months Ended
	Sep. 30, 2023
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers and Lease Income	REVENUE FROM CONTRACTS WITH CUSTOMERS AND LEASE INCOME Revenue from Contracts with Customers The Registrants generate revenues from a variety of sources, some of which are not accounted for as revenue from contracts with customers, such as leases, derivatives, and certain cost recovery mechanisms. See Note 1 to the financial statements under "Revenues" in Item 8 of the Form 10-K for additional information on the revenue policies of the Registrants. See "Lease Income" herein and Note (J) for additional information on revenue accounted for under lease and derivative accounting guidance, respectively. The following table disaggregates revenue from contracts with customers for the three and nine months ended September 30, 2023 and 2022: Southern Company Alabama Power Georgia Power Mississippi Power Southern Power Southern Company Gas (in millions) Three Months Ended September 30, 2023 Operating revenues Retail electric revenues Residential $ 2,543 $ 969 $ 1,473 $ 101 $ — $ — Commercial 1,845 599 1,151 95 — — Industrial 1,116 498 528 90 — — Other 30 3 25 2 — — Total retail electric revenues 5,534 2,069 3,177 288 — — Natural gas distribution revenues Residential 217 — — — — 217 Commercial 56 — — — — 56 Transportation 275 — — — — 275 Industrial 4 — — — — 4 Other 60 — — — — 60 Total natural gas distribution revenues 612 — — — — 612 Wholesale electric revenues PPA energy revenues 317 66 31 2 226 — PPA capacity revenues 151 26 13 3 110 — Non-PPA revenues 101 15 21 137 126 — Total wholesale electric revenues 569 107 65 142 462 — Other natural gas revenues Gas marketing services 54 — — — — 54 Other natural gas revenues 8 — — — — 8 Total natural gas revenues 62 — — — — 62 Other revenues 330 54 146 10 18 — Total revenue from contracts with customers 7,107 2,230 3,388 440 480 674 Other revenue sources (*) (127) (147) (151) (4) 173 15 Total operating revenues $ 6,980 $ 2,083 $ 3,237 $ 436 $ 653 $ 689 Southern Company Alabama Power Georgia Power Mississippi Power Southern Power Southern Company Gas (in millions) Nine Months Ended September 30, 2023 Operating revenues Retail electric revenues Residential $ 5,717 $ 2,277 $ 3,202 $ 238 $ — $ — Commercial 4,464 1,493 2,733 238 — — Industrial 2,770 1,324 1,195 251 — — Other 84 10 68 6 — — Total retail electric revenues 13,035 5,104 7,198 733 — — Natural gas distribution revenues Residential 1,443 — — — — 1,443 Commercial 370 — — — — 370 Transportation 878 — — — — 878 Industrial 33 — — — — 33 Other 228 — — — — 228 Total natural gas distribution revenues 2,952 — — — — 2,952 Wholesale electric revenues PPA energy revenues 853 196 66 8 601 — PPA capacity revenues 490 130 38 36 289 — Non-PPA revenues 199 49 30 315 312 — Total wholesale electric revenues 1,542 375 134 359 1,202 — Other natural gas revenues Gas marketing services 358 — — — — 358 Other natural gas revenues 28 — — — — 28 Total natural gas revenues 386 — — — — 386 Other revenues 971 159 422 31 46 — Total revenue from contracts with customers 18,886 5,638 7,754 1,123 1,248 3,338 Other revenue sources (*) 322 (218) 51 14 438 79 Total operating revenues $ 19,208 $ 5,420 $ 7,805 $ 1,137 $ 1,686 $ 3,417 Southern Company Alabama Power Georgia Power Mississippi Power Southern Power Southern Company Gas (in millions) Three Months Ended September 30, 2022 Operating revenues Retail electric revenues Residential $ 2,104 $ 799 $ 1,212 $ 93 $ — $ — Commercial 1,637 499 1,051 87 — — Industrial 1,183 452 642 89 — — Other 27 3 22 2 — — Total retail electric revenues 4,951 1,753 2,927 271 — — Natural gas distribution revenues Residential 331 — — — — 331 Commercial 93 — — — — 93 Transportation 259 — — — — 259 Industrial 12 — — — — 12 Other 49 — — — — 49 Total natural gas distribution revenues 744 — — — — 744 Wholesale electric revenues PPA energy revenues 812 187 40 4 591 — PPA capacity revenues 175 56 12 1 107 — Non-PPA revenues 58 67 4 242 303 — Total wholesale electric revenues 1,045 310 56 247 1,001 — Other natural gas revenues Gas marketing services 84 — — — — 84 Other natural gas revenues 15 — — — — 15 Total natural gas revenues 99 — — — — 99 Other revenues 277 65 110 13 9 — Total revenue from contracts with customers 7,116 2,128 3,093 531 1,010 843 Other revenue sources (*) 1,262 316 796 (21) 170 14 Total operating revenues $ 8,378 $ 2,444 $ 3,889 $ 510 $ 1,180 $ 857 Southern Company Alabama Power Georgia Power Mississippi Power Southern Power Southern Company Gas (in millions) Nine Months Ended September 30, 2022 Operating revenues Retail electric revenues Residential $ 5,282 $ 2,049 $ 2,995 $ 238 $ — $ — Commercial 4,202 1,285 2,688 229 — — Industrial 2,914 1,143 1,529 242 — — Other 79 10 62 7 — — Total retail electric revenues 12,477 4,487 7,274 716 — — Natural gas distribution revenues Residential 1,821 — — — — 1,821 Commercial 493 — — — — 493 Transportation 872 — — — — 872 Industrial 60 — — — — 60 Other 244 — — — — 244 Total natural gas distribution revenues 3,490 — — — — 3,490 Wholesale electric revenues PPA energy revenues 1,739 354 112 11 1,285 — PPA capacity revenues 443 135 35 4 273 — Non-PPA revenues 182 166 19 511 572 — Total wholesale electric revenues 2,364 655 166 526 2,130 — Other natural gas revenues Gas marketing services 417 — — — — 417 Other natural gas revenues 41 — — — — 41 Total natural gas revenues 458 — — — — 458 Other revenues 810 173 327 34 27 — Total revenue from contracts with customers 19,599 5,315 7,767 1,276 2,157 3,948 Other revenue sources (*) 2,633 708 1,451 3 461 50 Total operating revenues $ 22,232 $ 6,023 $ 9,218 $ 1,279 $ 2,618 $ 3,998 (*) Other revenue sources relate to revenues from customers accounted for as derivatives and leases, alternative revenue programs at Southern Company Gas, and cost recovery mechanisms and revenues (including those related to fuel costs) that meet other scope exceptions for revenues from contracts with customers at the traditional electric operating companies. Contract Balances The following table reflects the closing balances of receivables, contract assets, and contract liabilities related to revenues from contracts with customers at September 30, 2023 and December 31, 2022: Southern Company Alabama Power Georgia Power Mississippi Power Southern Power Southern Company Gas (in millions) Accounts Receivable At September 30, 2023 $ 2,680 $ 858 $ 1,175 $ 106 $ 138 $ 331 At December 31, 2022 3,123 696 922 92 237 1,107 Contract Assets At September 30, 2023 $ 267 $ 6 $ 146 $ — $ — $ 41 At December 31, 2022 156 2 89 — — — Contract Liabilities At September 30, 2023 $ 62 $ — $ 8 $ 2 $ 8 $ — At December 31, 2022 45 4 9 — 1 — Contract assets for Georgia Power primarily relate to retail customer fixed bill programs, where the payment is contingent upon Georgia Power's continued performance and the customer's continued participation in the program over a one-year contract term, and unregulated service agreements, where payment is contingent on project completion. Contract liabilities for Georgia Power primarily relate to cash collections recognized in advance of revenue for unregulated service agreements. At September 30, 2023, Southern Company Gas' contract assets relate to work performed on an energy efficiency enhancement and upgrade contract with the U.S. General Services Administration. Southern Company Gas receives cash advances from a third-party financial institution to fund work performed, of which approximately $51 million had been received at September 30, 2023. These advances have been accounted for as long-term debt on the balance sheets. See Note 1 to the financial statements under "Affiliate Transactions" in Item 8 of the Form 10-K for additional information regarding the construction contract. At September 30, 2023 and December 31, 2022, Southern Company's unregulated distributed generation business had contract assets of $75 million and $65 million, respectively, and contract liabilities of $47 million and $32 million, respectively, for outstanding performance obligations. Revenues recognized in the three and nine months ended September 30, 2023, which were included in contract liabilities at December 31, 2022, were immaterial for the applicable Registrants. Contract liabilities are primarily classified as current on the balance sheets as the corresponding revenues are generally expected to be recognized within one year. Remaining Performance Obligations The Subsidiary Registrants may enter into long-term contracts with customers in which revenues are recognized as performance obligations are satisfied over the contract term. For Alabama Power, Georgia Power, and Southern Power, these contracts primarily relate to PPAs whereby electricity and generation capacity are provided to a customer. The revenue recognized for the delivery of electricity is variable; however, certain PPAs include a fixed payment for fixed generation capacity over the term of the contract. For Southern Company Gas, these contracts primarily relate to the U.S. General Services Administration contract described above. Southern Company's unregulated distributed generation business also has partially satisfied performance obligations related to certain fixed price contracts. Revenues from contracts with customers related to these performance obligations remaining at September 30, 2023 are expected to be recognized as follows: 2023 (remaining) 2024 2025 2026 2027 Thereafter (in millions) Southern Company $ 166 $ 599 $ 359 $ 318 $ 319 $ 2,245 Alabama Power 10 24 8 — — — Georgia Power 23 66 34 14 14 23 Southern Power 84 356 302 303 310 2,233 Southern Company Gas 4 29 — — — — Lease Income Lease income for the three and nine months ended September 30, 2023 and 2022 is as follows: Southern Alabama Power Georgia Power Mississippi Southern Power Southern Company Gas (in millions) For the Three Months Ended September 30, 2023 Lease income - interest income on sales-type leases $ 6 $ — $ — $ 4 $ 2 $ — Lease income - operating leases 36 3 7 — 21 9 Variable lease income 134 — — — 144 — Total lease income $ 176 $ 3 $ 7 $ 4 $ 167 $ 9 For the Nine Months Ended September 30, 2023 Lease income - interest income on sales-type leases $ 18 $ — $ — $ 11 $ 7 $ — Lease income - operating leases 129 32 22 2 64 27 Variable lease income 327 1 — — 351 — Total lease income $ 474 $ 33 $ 22 $ 13 $ 422 $ 27 For the Three Months Ended September 30, 2022 Lease income - interest income on sales-type leases $ 7 $ — $ — $ 4 $ 3 $ — Lease income - operating leases 50 19 8 1 21 9 Variable lease income 139 — — — 145 — Total lease income $ 196 $ 19 $ 8 $ 5 $ 169 $ 9 For the Nine Months Ended September 30, 2022 Lease income - interest income on sales-type leases $ 19 $ — $ — $ 11 $ 8 $ — Lease income - operating leases 149 58 24 1 64 27 Variable lease income 355 1 — — 372 — Total lease income $ 523 $ 59 $ 24 $ 12 $ 444 $ 27 Lease payments received under tolling arrangements and PPAs consist of either scheduled payments or variable payments based on the amount of energy produced by the underlying electric generating units. Lease income for Alabama Power and Southern Power is included in wholesale revenues.

Consolidated Entities and Equit

Consolidated Entities and Equity Method Investments	9 Months Ended
	Sep. 30, 2023
Regulated Operations [Abstract]
Consolidated Entities and Equity Method Investments	CONSOLIDATED ENTITIES AND EQUITY METHOD INVESTMENTSSee Note 7 to the financial statements in Item 8 of the Form 10-K for additional information. Southern Company At September 30, 2023 and December 31, 2022, Southern Holdings had equity method investments totaling $126 million and $112 million, respectively, primarily related to investments in venture capital funds focused on energy and utility investments. Earnings from these investments were immaterial for all periods presented. Southern Power Variable Interest Entities Southern Power has certain subsidiaries that are determined to be VIEs. Southern Power is considered the primary beneficiary of these VIEs because it controls the most significant activities of the VIEs, including operating and maintaining the respective assets, and has the obligation to absorb expected losses of these VIEs to the extent of its equity interests. SP Solar and SP Wind At September 30, 2023 and December 31, 2022, SP Solar had total assets of $5.8 billion and $5.9 billion, respectively, total liabilities of $0.4 billion, and noncontrolling interests of $1.1 billion. Cash distributions from SP Solar are allocated 67% to Southern Power and 33% to the limited partner in accordance with their partnership interest percentage. Under the terms of the limited partnership agreement, distributions without limited partner consent are limited to available cash and SP Solar is obligated to distribute all such available cash to its partners each quarter. Available cash includes all cash generated in the quarter subject to the maintenance of appropriate operating reserves. At September 30, 2023 and December 31, 2022, SP Wind had total assets of $2.2 billion, total liabilities of $184 million and $169 million, respectively, and noncontrolling interests of $38 million and $39 million, respectively. Under the terms of the limited liability agreement, distributions without Class A member consent are limited to available cash and SP Wind is obligated to distribute all such available cash to its members each quarter. Available cash includes all cash generated in the quarter subject to the maintenance of appropriate operating reserves. Cash distributions from SP Wind are generally allocated 60% to Southern Power and 40% to the three financial investors in accordance with the limited liability agreement. Southern Power consolidates both SP Solar and SP Wind, as the primary beneficiary, since it controls the most significant activities of each entity, including operating and maintaining their assets. Certain transfers and sales of the assets in the VIEs are subject to partner consent and the liabilities are non-recourse to the general credit of Southern Power. Liabilities consist of customary working capital items and do not include any long-term debt. Other Variable Interest Entities Southern Power has other consolidated VIEs that relate to certain subsidiaries that have either sold noncontrolling interests to tax equity investors or acquired less than a 100% interest from facility developers. These entities are considered VIEs because the arrangements are structured similar to a limited partnership and the noncontrolling members do not have substantive kick-out rights. At September 30, 2023 and December 31, 2022, the other VIEs had total assets of $1.7 billion and $1.8 billion, respectively, total liabilities of $0.2 billion, and noncontrolling interests of $0.8 billion. Under the terms of the partnership agreements, distributions of all available cash are required each month or quarter and additional distributions require partner consent. Equity Method Investments At December 31, 2022, Southern Power had equity method investments in wind and battery energy storage projects totaling $49 million. During the first quarter 2023, Southern Power sold its remaining equity method investments in the projects and received proceeds of $50 million. Earnings (loss) from these investments, including the gains associated with the sales, were immaterial for all periods presented. Southern Company Gas Equity Method Investments The carrying amounts of Southern Company Gas' equity method investments at September 30, 2023 and December 31, 2022 and related earnings from those investments for the three and nine months ended September 30, 2023 and 2022 were as follows: Investment Balance September 30, 2023 December 31, 2022 (in millions) SNG $ 1,210 $ 1,243 Other 33 33 Total $ 1,243 $ 1,276 Three Months Ended September 30, Nine Months Ended September 30, Earnings from Equity Method Investments 2023 2022 2023 2022 (in millions) SNG $ 32 $ 34 $ 104 $ 104 Other — — — 1 Total $ 32 $ 34 $ 104 $ 105

Financing and Leases

Financing and Leases	9 Months Ended
	Sep. 30, 2023
Debt Disclosure [Abstract]
Financing and Leases	FINANCING AND LEASES Bank Credit Arrangements See Note 8 to the financial statements under "Bank Credit Arrangements" in Item 8 of the Form 10-K for additional information. At September 30, 2023, committed credit arrangements with banks were as follows: Expires Company 2024 2025 2026 2028 Total Unused Expires within (in millions) Southern Company parent (a) $ 150 $ — $ — $ 1,850 $ 2,000 $ 1,998 $ 150 Alabama Power — — 650 700 1,350 1,350 — Georgia Power — — — 1,750 1,750 1,726 — Mississippi Power — 125 150 — 275 275 — Southern Power (a)(b) — — — 600 600 589 — Southern Company Gas (c) 100 — — 1,500 1,600 1,598 100 SEGCO 30 — — — 30 30 30 Southern Company $ 280 $ 125 $ 800 $ 6,400 $ 7,605 $ 7,566 $ 280 (a) Arrangement expiring in 2028 represents a $2.45 billion combined arrangement for Southern Company and Southern Power as borrowers. Pursuant to the combined facility, the allocations between Southern Company and Southern Power may be adjusted. (b) Does not include Southern Power Company's $75 million and $100 million continuing letter of credit facilities for standby letters of credit, expiring in 2025 and 2026, respectively, of which $9 million and $16 million, respectively, was unused at September 30, 2023. In March 2023, Southern Power amended the $100 million letter of credit facility, which, among other things, extended the expiration date from 2025 to 2026 and increased the amount from $75 million. Southern Power's subsidiaries are not parties to its bank credit arrangements or letter of credit facilities. (c) Southern Company Gas, as the parent entity, guarantees the obligations of Southern Company Gas Capital, which is the borrower of $800 million of the credit arrangement expiring in 2028. Southern Company Gas' committed credit arrangement expiring in 2028 also includes $700 million for which Nicor Gas is the borrower and which is restricted for working capital needs of Nicor Gas. Pursuant to the multi-year credit arrangement expiring in 2028, the allocations between Southern Company Gas Capital and Nicor Gas may be adjusted. Nicor Gas is also the borrower under a $100 million credit arrangement expiring in 2024. As reflected in the table above, in May 2023, Southern Company and Southern Power combined and extended their multi-year credit arrangements previously maturing in 2026, resulting in a single aggregate $2.45 billion facility (currently allocated $1.85 billion for Southern Company and $600 million for Southern Power) maturing in 2028. Pursuant to the combined facility, the allocations between Southern Company and Southern Power may be adjusted. Alabama Power, Georgia Power, and Southern Company Gas Capital, along with Nicor Gas, amended and restated certain of their multi-year credit arrangements, which, among other things, extended the maturity dates from 2026 to 2028. Mississippi Power amended and restated certain of its multi-year credit arrangements aggregating $150 million, which, among other things, extended the maturity dates from 2024 to 2026. Nicor Gas also entered into a $100 million credit arrangement maturing in 2024 to replace its $250 million credit arrangement that expired in 2023. In June 2023, Southern Company also entered into a new $150 million credit arrangement maturing in 2024. In August 2023, Alabama Power amended and restated one of its multi-year credit arrangements, which, among other things, extended the maturity date from 2024 to 2026 and increased the borrowing capacity from $550 million to $650 million. Subject to applicable market conditions, Southern Company and its subsidiaries expect to renew or replace their bank credit arrangements as needed, prior to expiration. In connection therewith, Southern Company and its subsidiaries may extend the maturity dates and/or increase or decrease the lending commitments thereunder. These bank credit arrangements, as well as the term loan arrangements of the Registrants, Nicor Gas, and SEGCO, contain covenants that limit debt levels and contain cross-acceleration provisions to other indebtedness (including guarantee obligations) that are restricted only to the indebtedness of the individual company. The cross-acceleration provisions to other indebtedness would trigger an event of default if the applicable borrower defaulted on indebtedness, the payment of which was then accelerated. At September 30, 2023, the Registrants, Nicor Gas, and SEGCO were in compliance with all such covenants. None of the bank credit arrangements contain material adverse change clauses at the time of borrowings. A portion of the unused credit with banks is allocated to provide liquidity support to certain revenue bonds of the traditional electric operating companies and the commercial paper programs of the Registrants, Nicor Gas, and SEGCO. At September 30, 2023, outstanding variable rate demand revenue bonds of the traditional electric operating companies with allocated liquidity support totaled approximately $1.7 billion (comprised of approximately $818 million at Alabama Power, $819 million at Georgia Power, and $69 million at Mississippi Power). In addition, at September 30, 2023, Alabama Power and Georgia Power had approximately $120 million and $325 million, respectively, of fixed rate revenue bonds outstanding that are required to be remarketed within the next 12 months. The variable rate demand revenue bonds and fixed rate revenue bonds required to be remarketed within the next 12 months are classified as long-term debt on the balance sheets as a result of available long-term committed credit. Convertible Senior Notes In February 2023, Southern Company issued $1.5 billion aggregate principal amount of Series 2023A 3.875% Convertible Senior Notes due December 15, 2025 (Series 2023A Convertible Senior Notes). In March 2023, Southern Company issued an additional $225 million aggregate principal amount of the Series 2023A Convertible Senior Notes upon the exercise by the initial purchasers of their over-allotment option. Interest on the Series 2023A Convertible Senior Notes is payable semiannually, which began on June 15, 2023. The Series 2023A Convertible Senior Notes will mature on December 15, 2025, unless earlier converted or repurchased, but are not redeemable at the option of Southern Company. The Series 2023A Convertible Senior Notes are direct, unsecured, and unsubordinated obligations of Southern Company, ranking equally with all of Southern Company's other unsecured and unsubordinated indebtedness from time to time outstanding, and are effectively subordinated to all secured indebtedness of Southern Company. Holders may convert their Series 2023A Convertible Senior Notes at their option prior to the close of business on the business day preceding September 15, 2025, but only under the following circumstances: • during any calendar quarter (and only during such calendar quarter), if the last reported sale price of Southern Company's common stock for at least 20 trading days (whether or not consecutive) during the period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day as determined by Southern Company; • during the five business day period after any 10 consecutive trading day period (Measurement Period) in which the trading price per $1,000 principal amount of Series 2023A Convertible Senior Notes for each trading day of the Measurement Period was less than 98% of the product of the last reported sale price of the common stock and the conversion rate on each such trading day; or • upon the occurrence of certain corporate events specified in the indenture governing the Series 2023A Convertible Senior Notes. On or after September 15, 2025, a holder may convert all or any portion of its Series 2023A Convertible Senior Notes at any time prior to the close of business on the second scheduled trading day immediately preceding the maturity date regardless of the foregoing conditions. Southern Company will settle conversions of the Series 2023A Convertible Senior Notes by paying cash up to the aggregate principal amount of the Series 2023A Convertible Senior Notes to be converted and paying or delivering, as the case may be, cash, shares of common stock or a combination of cash and shares of common stock, at Southern Company's election, in respect of the remainder, if any, of Southern Company's conversion obligation in excess of the aggregate principal amount of the Series 2023A Convertible Senior Notes being converted. The Series 2023A Convertible Senior Notes are initially convertible at a rate of 11.8818 shares of common stock per $1,000 principal amount converted, which is approximately equal to $84.16 per share of common stock. The conversion rate will be subject to adjustment upon the occurrence of certain specified events but will not be adjusted for accrued and unpaid interest. In addition, upon the occurrence of a make-whole fundamental change (as defined in the indenture governing the Series 2023A Convertible Senior Notes), Southern Company will, in certain circumstances, increase the conversion rate by a number of additional shares of common stock for conversions in connection with the make-whole fundamental change. Upon the occurrence of a fundamental change (as defined in the indenture governing the Series 2023A Convertible Senior Notes), holders of the Series 2023A Convertible Senior Notes may require Southern Company to purchase all or a portion of their Series 2023A Convertible Senior Notes, in principal amounts equal to $1,000 or an integral multiple thereof, for cash at a price equal to 100% of the principal amount of the Series 2023A Convertible Senior Notes to be purchased plus any accrued and unpaid interest. Earnings per Share For Southern Company, the only difference in computing basic and diluted earnings per share (EPS) is attributable to awards outstanding under stock-based compensation plans and the Series 2023A Convertible Senior Notes. EPS dilution resulting from stock-based compensation plans is determined using the treasury stock method and EPS dilution resulting from the Series 2023A Convertible Senior Notes is determined using the net share settlement method. See Note 12 to the financial statements in Item 8 of the Form 10-K and "Convertible Senior Notes" herein for additional information. Shares used to compute diluted EPS were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 (in millions) As reported shares 1,092 1,082 1,092 1,070 Effect of stock-based compensation 7 6 6 6 Diluted shares 1,099 1,088 1,098 1,076 For all periods presented, an immaterial number of stock-based compensation awards was excluded from the diluted EPS calculation because the awards were anti-dilutive. For all periods presented, there was no dilution resulting from the Series 2023A Convertible Senior Notes. Southern Company Leveraged Lease See Note 9 to the financial statements in Item 8 of the Form 10-K for information on a leveraged lease agreement related to energy generation. In June 2022, the Southern Holdings subsidiary operating the generating plant for the lessee provided notice to the lessee to terminate the related operating and maintenance agreement effective June 30, 2023. Subsequently, the lessee failed to make the semi-annual lease payment due in December 2022. As a result, the Southern Holdings subsidiary was unable to make its corresponding payment to the holders of the underlying non-recourse debt related to the generation assets. The parties to the lease entered into forbearance agreements which suspended the related contractual rights of the parties while they continued restructuring negotiations, during which

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES See Note 10 to the financial statements in Item 8 of the Form 10-K for additional tax information. Current and Deferred Income Taxes Tax Credit and Net Operating Loss Carryforwards Southern Company had federal ITC and PTC carryforwards (primarily related to Southern Power) totaling $1.0 billion and $1.1 billion at September 30, 2023 and December 31, 2022, respectively. Southern Company's federal PTC and ITC carryforwards begin expiring in 2031, but are expected to be fully utilized by 2028. The utilization of each Registrant's estimated tax credit and state net operating loss carryforwards and related valuation allowances could be impacted by numerous factors, including the acquisition of additional renewable projects, changes in taxable income projections, transfer of eligible credits, and potential income tax rate changes. In the third quarter 2023, Georgia Power started generating advanced nuclear PTCs for Plant Vogtle Unit 3 beginning on the in-service date of July 31, 2023. In addition, pursuant to the Global Amendments to the Vogtle Joint Ownership Agreements (as defined in Note (B) under "Georgia Power – Nuclear Construction – Joint Owner Contracts"), Georgia Power is purchasing advanced nuclear PTCs for Plant Vogtle Unit 3 from certain other Vogtle Owners. See Note (B) and Note 2 to the financial statements in Item 8 of the Form 10-K under "Georgia Power – Nuclear Construction" for additional information on Plant Vogtle Units 3 and 4. Effective Tax Rate Southern Company's effective tax rate is typically lower than the statutory rate due to employee stock plans' dividend deduction, non-taxable AFUDC equity at the traditional electric operating companies, flowback of excess deferred income taxes at the regulated utilities, and federal income tax benefits from ITCs and PTCs primarily at Southern Power. Details of significant changes in the effective tax rate for the applicable Registrants are provided herein. Southern Company Southern Company's effective tax rate was 13.9% for the nine months ended September 30, 2023 compared to 20.0% for the corresponding period in 2022. The effective tax rate decrease was primarily due to an increase in the flowback of certain excess deferred income taxes at Alabama Power in 2023, lower pre-tax earnings in 2023, and an adjustment related to state tax credit carryforwards and the related valuation allowance at Georgia Power in 2022 and 2023, partially offset by the flowback of certain excess deferred income taxes ending in 2022 at Georgia Power. Alabama Power Alabama Power's effective tax rate was 8.3% for the nine months ended September 30, 2023 compared to 23.7% for the corresponding period in 2022. The effective tax rate decrease was primarily due to an increase in the flowback of certain excess deferred income taxes in 2023. See Note 2 to the financial statements under "Alabama Power – Excess Accumulated Deferred Income Tax Accounting Order" in Item 8 of the Form 10-K for additional information. Georgia Power Georgia Power's effective tax rate was 18.2% for the nine months ended September 30, 2023 compared to 18.5% for the corresponding period in 2022. The effective tax rate decrease was primarily due to an adjustment related to state tax credit carryforwards in 2022, a decrease in a valuation allowance on certain state tax credit carryforwards in 2023, and lower pre-tax earnings in 2023, largely offset by the flowback of certain excess deferred income taxes ending in 2022. Mississippi Power Mississippi Power's effective tax rate was 16.9% for the nine months ended September 30, 2023 compared to 20.1% for the corresponding period in 2022. The effective tax rate decrease was primarily due to an increase in the flowback of certain excess deferred income taxes in 2023. Southern Power Southern Power's effective tax rate was 14.8% for the nine months ended September 30, 2023 compared to 18.8% for the corresponding period in 2022. The effective tax rate decrease was primarily due to changes in state apportionment methodology resulting from tax legislation enacted by the State of Tennessee in May 2023. Unrecognized Tax Benefits Southern Company's and Georgia Power's unrecognized tax positions balances at September 30, 2023 were $167 million and $86 million, respectively, compared to $80 million for Southern Company at December 31, 2022. The increases from prior periods are primarily related to the amendment of certain 2019 through 2021 state tax filing positions related to tax credit utilization. If effective settlement of the positions is favorable, these positions would decrease Southern Company's and Georgia Power's effective tax rates. The ultimate outcome of this unrecognized tax benefit, of which a portion is expected to be resolved within the next 12 months, is dependent on acceptance by the state or expiration of related statute of limitations. Subsequent to September 30, 2023, a statute of limitations expired related to a 2019 state tax filing position to exclude certain gains from 2019 dispositions from taxation in a certain unitary state. This $44 million tax position and related interest will be recognized in the fourth quarter 2023 and will decrease Southern Company's annual effective tax rate.

Retirement Benefits

Retirement Benefits	9 Months Ended
	Sep. 30, 2023
Retirement Benefits [Abstract]
Retirement Benefits	RETIREMENT BENEFITS The Southern Company system has a qualified defined benefit, trusteed, pension plan covering substantially all employees, with the exception of employees at PowerSecure. The qualified pension plan is funded in accordance with requirements of the Employee Retirement Income Security Act of 1974, as amended (ERISA). No mandatory contributions to the qualified pension plan are anticipated for the year ending December 31, 2023. The Southern Company system also provides certain non-qualified defined benefits for a select group of management and highly compensated employees, which are funded on a cash basis. In addition, the Southern Company system provides certain medical care and life insurance benefits for retired employees through other postretirement benefit plans. The traditional electric operating companies fund other postretirement trusts to the extent required by their respective regulatory commissions. Southern Company Gas has a separate unfunded supplemental retirement health care plan that provides medical care and life insurance benefits to employees of discontinued businesses. See Note 11 to the financial statements in Item 8 of the Form 10-K for additional information. On each Registrant's condensed statements of income, the service cost component of net periodic benefit costs is included in other operations and maintenance expenses and all other components of net periodic benefit costs are included in other income (expense), net. Components of the net periodic benefit costs for the three and nine months ended September 30, 2023 and 2022 are presented in the following tables. Southern Alabama Georgia Mississippi Southern Power Southern Company Gas (in millions) Three Months Ended September 30, 2023 Pension Plans Service cost $ 69 $ 16 $ 17 $ 2 $ 2 $ 6 Interest cost 156 37 48 7 2 11 Expected return on plan assets (307) (75) (97) (13) (4) (22) Amortization: Prior service costs — — — — — (1) Regulatory asset — — — — — 4 Net (gain) loss 8 2 4 1 — (1) Net periodic pension income $ (74) $ (20) $ (28) $ (3) $ — $ (3) Postretirement Benefits Service cost $ 4 $ 1 $ 1 $ — $ — $ — Interest cost 18 5 6 1 — 2 Expected return on plan assets (21) (9) (7) (1) — (2) Amortization: Prior service costs — — 1 — — — Regulatory asset — — — — — 2 Net gain (4) (1) (1) — — (1) Net periodic postretirement benefit cost (income) $ (3) $ (4) $ — $ — $ — $ 1 Nine Months Ended September 30, 2023 Pension Plans Service cost $ 207 $ 48 $ 51 $ 8 $ 5 $ 18 Interest cost 469 109 143 21 6 32 Expected return on plan assets (922) (223) (289) (41) (12) (65) Amortization: Prior service costs — — 1 — — (2) Regulatory asset — — — — — 11 Net (gain) loss 24 7 10 1 — (3) Net periodic pension income $ (222) $ (59) $ (84) $ (11) $ (1) $ (9) Postretirement Benefits Service cost $ 11 $ 3 $ 3 $ — $ — $ 1 Interest cost 53 13 19 2 — 6 Expected return on plan assets (62) (26) (22) (1) — (5) Amortization: Prior service costs 1 — 1 — — — Regulatory asset — — — — — 5 Net gain (10) (2) (3) — — (3) Net periodic postretirement benefit cost (income) $ (7) $ (12) $ (2) $ 1 $ — $ 4 Southern Alabama Georgia Mississippi Southern Power Southern Company Gas (in millions) Three Months Ended September 30, 2022 Pension Plans Service cost $ 103 $ 25 $ 26 $ 5 $ 2 $ 9 Interest cost 102 24 31 5 2 7 Expected return on plan assets (316) (77) (99) (15) (4) (22) Amortization: Prior service costs — — — — — (1) Regulatory asset — — — — — 3 Net loss 60 16 18 2 1 2 Net periodic pension cost (income) $ (51) $ (12) $ (24) $ (3) $ 1 $ (2) Postretirement Benefits Service cost $ 6 $ 2 $ 2 $ 1 $ 1 $ — Interest cost 10 3 4 — — 1 Expected return on plan assets (20) (9) (8) — — (2) Amortization: Prior service costs (1) — — — — — Regulatory asset — — — — — 2 Net (gain)/loss 1 — — — — (1) Net periodic postretirement benefit cost (income) $ (4) $ (4) $ (2) $ 1 $ 1 $ — Nine Months Ended September 30, 2022 Pension Plans Service cost $ 309 $ 74 $ 78 $ 13 $ 7 $ 26 Interest cost 306 72 92 14 5 21 Expected return on plan assets (949) (229) (298) (44) (12) (68) Amortization: Prior service costs — — 1 — — (2) Regulatory asset — — — — — 11 Net loss 180 47 55 9 2 5 Net periodic pension cost (income) $ (154) $ (36) $ (72) $ (8) $ 2 $ (7) Postretirement Benefits Service cost $ 17 $ 5 $ 5 $ 1 $ 1 $ 1 Interest cost 31 8 11 1 — 4 Expected return on plan assets (60) (25) (21) (1) — (6) Amortization: Prior service costs (1) — — — — — Regulatory asset — — — — — 5 Net (gain) loss 1 — 1 — — (2) Net periodic postretirement benefit cost (income) $ (12) $ (12) $ (4) $ 1 $ 1 $ 2

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS At September 30, 2023, assets and liabilities measured at fair value on a recurring basis during the period, together with their associated level of the fair value hierarchy, were as follows: Fair Value Measurements Using: At September 30, 2023 Quoted Prices Significant Significant Net Asset Value as a Practical Expedient (NAV) Total (in millions) Southern Company Assets: Energy-related derivatives (a) $ 7 $ 73 $ — $ — $ 80 Investments in trusts: (b) Domestic equity 692 196 — — 888 Foreign equity 131 154 — — 285 U.S. Treasury and government agency securities — 337 — — 337 Municipal bonds — 42 — — 42 Pooled funds – fixed income — 6 — — 6 Corporate bonds — 368 — — 368 Mortgage and asset backed securities — 85 — — 85 Private equity — — — 169 169 Cash and cash equivalents 3 — — — 3 Other 33 3 — 8 44 Cash equivalents and restricted cash 919 11 — — 930 Other investments 9 34 8 — 51 Total $ 1,794 $ 1,309 $ 8 $ 177 $ 3,288 Liabilities: Energy-related derivatives (a) $ 34 $ 217 $ — $ — $ 251 Interest rate derivatives — 351 — — 351 Foreign currency derivatives — 192 — — 192 Contingent consideration 5 — 19 — 24 Other — 13 — — 13 Total $ 39 $ 773 $ 19 $ — $ 831 Fair Value Measurements Using: At September 30, 2023 Quoted Prices Significant Significant Net Asset Value as a Practical Expedient (NAV) Total (in millions) Alabama Power Assets: Energy-related derivatives $ — $ 26 $ — $ — $ 26 Nuclear decommissioning trusts: (b) Domestic equity 404 188 — — 592 Foreign equity 131 — — — 131 U.S. Treasury and government agency securities — 20 — — 20 Municipal bonds — 1 — — 1 Corporate bonds — 215 — — 215 Mortgage and asset backed securities — 22 — — 22 Private equity — — — 169 169 Other 10 — — 8 18 Cash equivalents and restricted cash 489 11 — — 500 Other investments — 34 — — 34 Total $ 1,034 $ 517 $ — $ 177 $ 1,728 Liabilities: Energy-related derivatives $ — $ 75 $ — $ — $ 75 Georgia Power Assets: Energy-related derivatives $ — $ 14 $ — $ — $ 14 Nuclear decommissioning trusts: (b) Domestic equity 288 1 — — 289 Foreign equity — 153 — — 153 U.S. Treasury and government agency securities — 317 — — 317 Municipal bonds — 41 — — 41 Corporate bonds — 153 — — 153 Mortgage and asset backed securities — 63 — — 63 Other 23 3 — — 26 Total $ 311 $ 745 $ — $ — $ 1,056 Liabilities: Energy-related derivatives $ — $ 83 $ — $ — $ 83 Fair Value Measurements Using: At September 30, 2023 Quoted Prices Significant Significant Net Asset Value as a Practical Expedient (NAV) Total (in millions) Mississippi Power Assets: Energy-related derivatives $ — $ 24 $ — $ — $ 24 Cash equivalents 3 — — — 3 Total $ 3 $ 24 $ — $ — $ 27 Liabilities: Energy-related derivatives $ — $ 44 $ — $ — $ 44 Southern Power Assets: Energy-related derivatives $ — $ 5 $ — $ — $ 5 Cash equivalents 23 — — — 23 Total $ 23 $ 5 $ — $ — $ 28 Liabilities: Energy-related derivatives $ — $ 6 $ — $ — $ 6 Foreign currency derivatives — 42 — — 42 Contingent consideration 5 — 19 — 24 Other — 13 — — 13 Total $ 5 $ 61 $ 19 $ — $ 85 Southern Company Gas Assets: Energy-related derivatives (a) $ 7 $ 4 $ — $ — $ 11 Non-qualified deferred compensation trusts: Domestic equity — 7 — — 7 Foreign equity — 1 — — 1 Pooled funds – fixed income — 6 — — 6 Cash equivalents 3 — — — 3 Cash equivalents 294 — — — 294 Total $ 304 $ 18 $ — $ — $ 322 Liabilities: Energy-related derivatives (a) $ 34 $ 9 $ — $ — $ 43 Interest rate derivatives — 99 — — 99 Total $ 34 $ 108 $ — $ — $ 142 (a) Excludes cash collateral of $49 million. (b) Excludes receivables related to investment income, pending investment sales, payables related to pending investment purchases, and currencies. See Note 6 to the financial statements in Item 8 of the Form 10-K for additional information. Southern Company, Alabama Power, and Georgia Power continue to elect the option to fair value investment securities held in the nuclear decommissioning trust funds. The fair value of the funds, including reinvested interest and dividends and excluding the funds' expenses, increased (decreased) by the amounts shown in the table below for the three and nine months ended September 30, 2023 and 2022. The changes were recorded as a change to the regulatory assets and liabilities related to AROs for Georgia Power and Alabama Power, respectively. Three Months Ended Nine Months Ended Fair value increases (decreases) September 30, 2023 September 30, 2022 September 30, 2023 September 30, 2022 (in millions) Southern Company $ (4) $ (106) $ 211 $ (486) Alabama Power (36) (53) 54 (245) Georgia Power 32 (53) 157 (241) Valuation Methodologies The energy-related derivatives primarily consist of exchange-traded and over-the-counter financial products for natural gas and physical power products, including, from time to time, basis swaps. These are standard products used within the energy industry and are valued using the market approach. The inputs used are mainly from observable market sources, such as forward natural gas prices, power prices, implied volatility, and overnight index swap interest rates. Interest rate derivatives are also standard over-the-counter products that are valued using observable market data and assumptions commonly used by market participants. The fair value of interest rate derivatives reflects the net present value of expected payments and receipts under the swap agreement based on the market's expectation of future interest rates. Additional inputs to the net present value calculation may include the contract terms, counterparty credit risk, and occasionally, implied volatility of interest rate options. The fair value of cross-currency swaps reflects the net present value of expected payments and receipts under the swap agreement based on the market's expectation of future foreign currency exchange rates. Additional inputs to the net present value calculation may include the contract terms, counterparty credit risk, and discount rates. The interest rate derivatives and cross-currency swaps are categorized as Level 2 under Fair Value Measurements as these inputs are based on observable data and valuations of similar instruments. See Note (J) for additional information on how these derivatives are used. For fair value measurements of the investments within the nuclear decommissioning trusts and the non-qualified deferred compensation trusts, external pricing vendors are designated for each asset class with each security specifically assigned a primary pricing source. For investments held within commingled funds, fair value is determined at the end of each business day through the net asset value, which is established by obtaining the underlying securities' individual prices from the primary pricing source. A market price secured from the primary source vendor is then evaluated by management in its valuation of the assets within the trusts. As a general approach, fixed income market pricing vendors gather market data (including indices and market research reports) and integrate relative credit information, observed market movements, and sector news into proprietary pricing models, pricing systems, and mathematical tools. Dealer quotes and other market information, including live trading levels and pricing analysts' judgments, are also obtained when available. The NRC requires licensees of commissioned nuclear power reactors to establish a plan for providing reasonable assurance of funds for future decommissioning. See Note 6 to the financial statements under "Nuclear Decommissioning" in Item 8 of the Form 10-K for additional information. Southern Power has contingent payment obligations related to two of its acquisitions whereby it is primarily obligated to make generation-based payments to the seller, commencing at the commercial operation of each facility and continuing through 2026 and 2035, respectively. The obligations are primarily categorized as Level 3 under Fair Value Measurements as the fair value is determined using significant unobservable inputs for the forecasted facility's generation in MW-hours, as well as other inputs such as a fixed dollar amount per MW-hour, and a discount rate. The fair value of contingent consideration reflects the net present value of expected payments and any periodic change arising from forecasted generation is expected to be immaterial. Southern Power also has payment obligations through 2040 whereby it must reimburse the transmission owners for interconnection facilities and network upgrades constructed to support connection of a Southern Power generating facility to the transmission system. The obligations are categorized as Level 2 under Fair Value Measurements as the fair value is determined using observable inputs for the contracted amounts and reimbursement period, as well as a discount rate. The fair value of the obligations reflects the net present value of expected payments. "Other investments" primarily includes investments traded in the open market that have maturities greater than 90 days, which are categorized as Level 2 under Fair Value Measurements and are comprised of corporate bonds, bank certificates of deposit, treasury bonds, and/or agency bonds. At September 30, 2023, the fair value measurements of private market investments held in Alabama Power's nuclear decommissioning trusts that are calculated at net asset value per share (or its equivalent) as a practical expedient totaled $177 million and unfunded commitments related to the private market investments totaled $72 million. Private market investments include high-quality private equity funds across several market sectors, funds that invest in real estate assets, and a private credit fund. Private market funds do not have redemption rights. Distributions from these funds will be received as the underlying investments in the funds are liquidated. At September 30, 2023, other financial instruments for which the carrying amount did not equal fair value were as follows: Southern Company (*) Alabama Power Georgia Power Mississippi Power Southern Power Southern Company Gas (*) (in billions) Long-term debt, including securities due within one year: Carrying amount $ 58.8 $ 11.2 $ 15.8 $ 1.6 $ 2.7 $ 8.1 Fair value 50.8 9.4 13.4 1.3 2.4 6.5 (*) The carrying amount of Southern Company Gas' long-term debt includes fair value adjustments from the effective date of the 2016 merger with Southern Company. Southern Company Gas amortizes the fair value adjustments over the remaining lives of the respective bonds, the latest being through 2043. The fair values are determined using Level 2 measurements and are based on quoted market prices for the same or similar issues or on the current rates available to the Registrants.

Derivatives

Derivatives	9 Months Ended
	Sep. 30, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	DERIVATIVESThe Registrants are exposed to market risks, including commodity price risk, interest rate risk, weather risk, and occasionally foreign currency exchange rate risk. To manage the volatility attributable to these exposures, each company nets its exposures, where possible, to take advantage of natural offsets and enters into various derivative transactions for the remaining exposures pursuant to each company's policies in areas such as counterparty exposure and risk management practices. For the traditional electric operating companies, Southern Power, and Southern Company Gas' other businesses, each company's policy is that derivatives are to be used primarily for hedging purposes and mandates strict adherence to all applicable risk management policies. Derivative positions are monitored using techniques including, but not limited to, market valuation, value at risk, stress testing, and sensitivity analysis. Derivative instruments are recognized at fair value in the balance sheets as either assets or liabilities and are presented on a net basis. See Note (I) for additional fair value information. In the statements of cash flows, any cash impacts of settled energy-related and interest rate derivatives are recorded as operating activities. Any cash impacts of settled foreign currency derivatives are classified as operating or financing activities to correspond with the classification of the hedged interest or principal, respectively. See Note 1 to the financial statements under "Financial Instruments" in Item 8 of the Form 10-K for additional information. Energy-Related Derivatives The Subsidiary Registrants enter into energy-related derivatives to hedge exposures to electricity, natural gas, and other fuel price changes. However, due to cost-based rate regulations and other various cost recovery mechanisms, the traditional electric operating companies and the natural gas distribution utilities have limited exposure to market volatility in energy-related commodity prices. Each of the traditional electric operating companies and certain of the natural gas distribution utilities of Southern Company Gas manage fuel-hedging programs, implemented per the guidelines of their respective state PSCs or other applicable state regulatory agencies, through the use of financial derivative contracts, which are expected to continue to mitigate price volatility. The traditional electric operating companies (with respect to wholesale generating capacity) and Southern Power have limited exposure to market volatility in energy-related commodity prices because their long-term sales contracts shift substantially all fuel cost responsibility to the purchaser. However, the traditional electric operating companies and Southern Power may be exposed to market volatility in energy-related commodity prices to the extent any uncontracted capacity is used to sell electricity. Southern Company Gas retains exposure to price changes that can, in a volatile energy market, be material and can adversely affect its results of operations. Southern Company Gas also enters into weather derivative contracts as economic hedges in the event of warmer-than-normal weather. Exchange-traded options are carried at fair value, with changes reflected in operating revenues. Non-exchange-traded options are accounted for using the intrinsic value method. Changes in the intrinsic value for non-exchange-traded contracts are reflected in operating revenues. Energy-related derivative contracts are accounted for under one of three methods: • Regulatory Hedges – Energy-related derivative contracts designated as regulatory hedges relate primarily to the traditional electric operating companies' and the natural gas distribution utilities' fuel-hedging programs, where gains and losses are initially recorded as regulatory liabilities and assets, respectively, and then are included in fuel expense as the underlying fuel is used in operations and ultimately recovered through an approved cost recovery mechanism. • Cash Flow Hedges – Gains and losses on energy-related derivatives designated as cash flow hedges (which are mainly used to hedge anticipated purchases and sales) are initially deferred in accumulated OCI before being recognized in the statements of income in the same period and in the same income statement line item as the earnings effect of the hedged transactions. • Not Designated – Gains and losses on energy-related derivative contracts that are not designated or fail to qualify as hedges are recognized in the statements of income as incurred. Some energy-related derivative contracts require physical delivery as opposed to financial settlement, and this type of derivative is both common and prevalent within the electric and natural gas industries. When an energy-related derivative contract is settled physically, any cumulative unrealized gain or loss is reversed and the contract price is recognized in the respective line item representing the actual price of the underlying goods being delivered. At September 30, 2023, the net volume of energy-related derivative contracts for natural gas positions, together with the longest hedge date over which the respective entity is hedging its exposure to the variability in future cash flows for forecasted transactions and the longest non-hedge date for derivatives not designated as hedges, were as follows: Net Longest Longest (in millions) Southern Company (*) 422 2030 2028 Alabama Power 109 2026 — Georgia Power 104 2026 — Mississippi Power 80 2027 — Southern Power 8 2030 2024 Southern Company Gas (*) 121 2027 2028 (*) Southern Company Gas' derivative instruments include both long and short natural gas positions. A long position is a contract to purchase natural gas and a short position is a contract to sell natural gas. Southern Company Gas' volume represents the net of 135.5 million mmBtu long natural gas positions and 14.2 million mmBtu short natural gas positions at September 30, 2023, which is also included in Southern Company's total volume. In addition to the volumes discussed above, the traditional electric operating companies and Southern Power enter into physical natural gas supply contracts that provide the option to sell back excess natural gas due to operational constraints. The maximum expected volume of natural gas subject to such a feature is 14 million mmBtu for Southern Company, which includes 4 million mmBtu for Alabama Power, 5 million mmBtu for Georgia Power, 2 million mmBtu for Mississippi Power, and 3 million mmBtu for Southern Power. For cash flow hedges of energy-related derivatives, the estimated pre-tax losses expected to be reclassified from accumulated OCI to earnings for the 12-month period ending September 30, 2024 are $30 million for Southern Company, $25 million for Southern Company Gas, and immaterial for Southern Power. Interest Rate Derivatives Southern Company and certain subsidiaries may enter into interest rate derivatives to hedge exposure to changes in interest rates. Derivatives related to existing variable rate securities or forecasted transactions are accounted for as cash flow hedges where the derivatives' fair value gains or losses are recorded in OCI and are reclassified into earnings at the same time and presented on the same income statement line item as the earnings effect of the hedged transactions. Derivatives related to existing fixed rate securities are accounted for as fair value hedges, where the derivatives' fair value gains or losses and hedged items' fair value gains or losses are both recorded directly to earnings on the same income statement line item. Fair value gains or losses on derivatives that are not designated or fail to qualify as hedges are recognized in the statements of income as incurred. At September 30, 2023, the following interest rate derivatives were outstanding: Notional Weighted Interest Hedge Fair Value Gain (Loss) at September 30, 2023 (in millions) (in millions) Fair Value Hedges of Existing Debt Southern Company parent $ 400 1-month SOFR + 0.80% 1.75% March 2028 $ (56) Southern Company parent 1,000 1-month SOFR + 2.48% 3.70% April (196) Southern Company Gas 500 1-month SOFR + 0.49% 1.75% January 2031 (99) Southern Company $ 1,900 $ (351) For cash flow hedges of interest rate derivatives, the estimated pre-tax losses expected to be reclassified from accumulated OCI to interest expense for the 12-month period ending September 30, 2024 are $19 million for Southern Company and immaterial for the traditional electric operating companies and Southern Company Gas. Deferred gains and losses related to interest rate derivatives are expected to be amortized into earnings through 2052 for Southern Company, Alabama Power, and Georgia Power, 2028 for Mississippi Power, and 2046 for Southern Company Gas. Foreign Currency Derivatives Southern Company and certain subsidiaries, including Southern Power, may enter into foreign currency derivatives to hedge exposure to changes in foreign currency exchange rates, such as that arising from the issuance of debt denominated in a currency other than U.S. dollars. Derivatives related to forecasted transactions are accounted for as cash flow hedges where the derivatives' fair value gains or losses are recorded in OCI and are reclassified into earnings at the same time and on the same income statement line as the earnings effect of the hedged transactions, including foreign currency gains or losses arising from changes in the U.S. currency exchange rates. Derivatives related to existing fixed rate securities are accounted for as fair value hedges, where the derivatives' fair value gains or losses and hedged items' fair value gains or losses are both recorded directly to earnings on the same income statement line item, including foreign currency gains or losses arising from changes in the U.S. currency exchange rates. Southern Company has elected to exclude the cross-currency basis spread from the assessment of effectiveness in the fair value hedges of its foreign currency risk and record any difference between the change in the fair value of the excluded components and the amounts recognized in earnings as a component of OCI. At September 30, 2023, the following foreign currency derivatives were outstanding: Pay Notional Pay Receive Notional Receive Hedge Fair Value Gain (Loss) at September 30, 2023 (in millions) (in millions) (in millions) Cash Flow Hedges of Existing Debt Southern Power $ 564 3.78% € 500 1.85% June 2026 $ (42) Fair Value Hedges of Existing Debt Southern Company parent 1,476 3.39% 1,250 1.88% September 2027 (150) Southern Company $ 2,040 € 1,750 $ (192) For cash flow hedges of foreign currency derivatives, the estimated pre-tax losses expected to be reclassified from accumulated OCI to earnings for the 12-month period ending September 30, 2024 are $10 million for Southern Power. Derivative Financial Statement Presentation and Amounts The Registrants enter into derivative contracts that may contain certain provisions that permit intra-contract netting of derivative receivables and payables for routine billing and offsets related to events of default and settlements. Southern Company and certain subsidiaries also utilize master netting agreements to mitigate exposure to counterparty credit risk. These agreements may contain provisions that permit netting across product lines and against cash collateral. The fair value amounts of derivative assets and liabilities on the balance sheets are presented net to the extent that there are netting arrangements or similar agreements with the counterparties. The fair value of energy-related derivatives, interest rate derivatives, and foreign currency derivatives was reflected in the balance sheets as follows: At September 30, 2023 At December 31, 2022 Derivative Category and Balance Sheet Location Assets Liabilities Assets Liabilities (in millions) (in millions) Southern Company Energy-related derivatives designated as hedging instruments for regulatory purposes Assets from risk management activities/Liabilities from risk management activities $ 34 $ 134 $ 123 $ 121 Other deferred charges and assets/Other deferred credits and liabilities 36 77 52 44 Total derivatives designated as hedging instruments for regulatory purposes 70 211 175 165 Derivatives designated as hedging instruments in cash flow and fair value hedges Energy-related derivatives: Assets from risk management activities/Liabilities from risk management activities — 28 3 27 Other deferred charges and assets/Other deferred credits and liabilities 4 2 6 4 Interest rate derivatives: Assets from risk management activities/Liabilities from risk management activities — 80 12 62 Other deferred charges and assets/Other deferred credits and liabilities — 271 — 240 Foreign currency derivatives: Assets from risk management activities/Liabilities from risk management activities — 35 — 34 Other deferred charges and assets/Other deferred credits and liabilities — 157 — 182 Total derivatives designated as hedging instruments in cash flow and fair value hedges 4 573 21 549 Energy-related derivatives not designated as hedging instruments Assets from risk management activities/Liabilities from risk management activities 5 8 13 13 Other deferred charges and assets/Other deferred credits and liabilities 1 2 2 1 Total derivatives not designated as hedging instruments 6 10 15 14 Gross amounts recognized 80 794 211 728 Gross amounts offset (a) (37) (86) (70) (111) Net amounts recognized in the Balance Sheets (b) $ 43 $ 708 $ 141 $ 617 At September 30, 2023 At December 31, 2022 Derivative Category and Balance Sheet Location Assets Liabilities Assets Liabilities (in millions) (in millions) Alabama Power (c) Energy-related derivatives designated as hedging instruments for regulatory purposes Other current assets/Other current liabilities $ 15 $ 46 $ 42 $ 21 Other deferred charges and assets/Other deferred credits and liabilities 11 29 20 18 Total derivatives designated as hedging instruments for regulatory purposes 26 75 62 39 Gross amounts offset (17) (17) (24) (24) Net amounts recognized in the Balance Sheets $ 9 $ 58 $ 38 $ 15 Georgia Power Energy-related derivatives designated as hedging instruments for regulatory purposes Other current assets/Other current liabilities $ 4 $ 57 $ 36 $ 43 Other deferred charges and assets/Other deferred credits and liabilities 10 26 6 18 Total derivatives designated as hedging instruments for regulatory purposes 14 83 42 61 Energy-related derivatives not designated as hedging instruments Other current assets/Other current liabilities — — — 1 Gross amounts recognized 14 83 42 62 Gross amounts offset (11) (11) (21) (21) Net amounts recognized in the Balance Sheets $ 3 $ 72 $ 21 $ 41 Mississippi Power (c) Energy-related derivatives designated as hedging instruments for regulatory purposes Other current assets/Other current liabilities $ 9 $ 22 $ 33 $ 24 Other deferred charges and assets/Other deferred credits and liabilities 15 22 26 8 Total derivatives designated as hedging instruments for regulatory purposes 24 44 59 32 Gross amounts offset (17) (17) (17) (17) Net amounts recognized in the Balance Sheets $ 7 $ 27 $ 42 $ 15 At September 30, 2023 At December 31, 2022 Derivative Category and Balance Sheet Location Assets Liabilities Assets Liabilities (in millions) (in millions) Southern Power Derivatives designated as hedging instruments in cash flow and fair value hedges Energy-related derivatives: Other current assets/Other current liabilities $ — $ 5 $ — $ 12 Other deferred charges and assets/Other deferred credits and liabilities 4 — 5 — Foreign currency derivatives: Other current assets/Other current liabilities — 11 — 11 Other deferred charges and assets/Other deferred credits and liabilities — 31 — 36 Total derivatives designated as hedging instruments in cash flow and fair value hedges 4 47 5 59 Energy-related derivatives not designated as hedging instruments Other current assets/Other current liabilities 1 1 2 — Other deferred charges and assets/Other deferred credits and liabilities — — 1 — Total derivatives not designated as hedging instruments 1 1 3 — Gross amounts recognized 5 48 8 59 Gross amounts offset (1) (1) — — Net amounts recognized in the Balance Sheets $ 4 $ 47 $ 8 $ 59 Southern Company Gas Energy-related derivatives designated as hedging instruments for regulatory purposes Other current assets/Other current liabilities $ 6 $ 9 $ 12 $ 33 Derivatives designated as hedging instruments in cash flow and fair value hedges Energy-related derivatives: Other current assets/Other current liabilities — 23 3 15 Other deferred charges and assets/Other deferred credits and liabilities — 2 1 4 Interest rate derivatives: Other current assets/Other current liabilities — 21 — 14 Other deferred charges and assets/Other deferred credits and liabilities — 78 — 72 Total derivatives designated as hedging instruments in cash flow and fair value hedges — 124 4 105 Energy-related derivatives not designated as hedging instruments Other current assets/Other current liabilities 4 7 11 12 Other deferred charges and assets/Other deferred credits and liabilities 1 2 1 1 Total derivatives not designated as hedging instruments 5 9 12 13 Gross amounts recognized 11 142 28 151 Gross amounts offset (a) 9 (40) — (41) Net amounts recognized in the Balance Sheets (b) $ 20 $ 102 $ 28 $ 110 (a) Gross amounts offset includes cash collateral held on deposit in broker margin accounts of $49 million and $41 million at September 30, 2023 and December 31, 2022, respectively. (b) Net amounts of derivative instruments outstanding exclude immaterial premium and intrinsic value associated with weather derivatives for both periods presented. (c) Energy-related derivatives not designated as hedging instruments were immaterial for Alabama Power and Mississippi Power at December 31, 2022. There were no such instruments for Alabama Power and Mississippi Power at September 30, 2023. At September 30, 2023 and December 31, 2022, the pre-tax effects of unrealized derivative gains (losses) arising from energy-related derivative instruments designated as regulatory hedging instruments and deferred were as follows: Regulatory Hedge Unrealized Gain (Loss) Recognized in the Balance Sheet Derivative Category and Balance Sheet Southern Alabama Georgia Mississippi Southern Company Gas (in millions) At September 30, 2023: Energy-related derivatives: Other regulatory assets, current $ (113) $ (39) $ (54) $ (16) $ (4) Other regulatory assets, deferred (48) (19) (18) (11) — Other regulatory liabilities, current 23 8 1 4 10 Other regulatory liabilities, deferred 6 1 2 3 — Total energy-related derivative gains (losses) $ (132) $ (49) $ (69) $ (20) $ 6 At December 31, 2022: Energy-related derivatives: Other regulatory assets, current $ (71) $ (8) $ (26) $ (13) $ (24) Other regulatory assets, deferred (23) (7) (14) (2) — Other regulatory liabilities, current 72 29 19 22 2 Other regulatory liabilities, deferred 31 9 2 20 — Total energy-related derivative gains (losses) $ 9 $ 23 $ (19) $ 27 $ (22) For the three and nine months ended September 30, 2023 and 2022, the pre-tax effects of cash flow and fair value hedge accounting on accumulated OCI for the applicable Registrants were as follows: Gain (Loss) Recognized in OCI on Derivatives For the Three Months Ended September 30, For the Nine Months Ended September 30, 2023 2022 2023 2022 (in millions) (in millions) Southern Company Cash flow hedges: Energy-related derivatives $ (4) $ 11 $ (55) $ 51 Interest rate derivatives (3) 6 (12) 36 Foreign currency derivatives (15) (35) (6) (137) Fair value hedges (*) : Foreign currency derivatives 27 20 28 18 Total $ 5 $ 2 $ (45) $ (32) Georgia Power Cash flow hedges: Interest rate derivatives $ — $ — $ (3) $ 31 Southern Power Cash flow hedges: Energy-related derivatives $ — $ (11) $ (14) $ (4) Foreign currency derivatives (15) (35) (6) (137) Total $ (15) $ (46) $ (20) $ (141) Southern Company Gas Cash flow hedges: Energy-related derivatives $ (4) $ 22 $ (41) $ 55 Interest rate derivatives (4) 5 — — Total $ (8) $ 27 $ (41) $ 55 (*) Represents amounts excluded from the assessment of effectiveness for which the difference between changes in fair value and periodic amortization is recorded in OCI. For the three and nine months ended September 30, 2022, the pre-tax effects of interest rate derivatives designated as cash flow hedging instruments on accumulated OCI were immaterial for Alabama Power and there were no such effects in 2023. For the three and nine months ended September 30, 2023 and 2022, the pre-tax effects of cash flow and fair value hedge accounting on income were as follows: Location and Amount of Gain (Loss) Recognized in Income on Cash Flow and Fair Value Hedging Relationships For the Three Months Ended September 30, For the Nine Months Ended September 30, 2023 2022 2023 2022 (in millions) (in millions) Southern Company Total cost of natural gas $ 102 $ 294 $ 1,199 $ 1,840 Gain (loss) on energy-related cash flow hedges (a) (4) 9 (32) 28 Total other operations and maintenance 1,424 1,527 4,352 4,568 Gain (loss) on energy-related cash flow hedges (a) (1) — (2) — Total depreciation and amortization 1,143 922 3,365 2,728 Gain (loss) on energy-related cash flow hedges (a) (5) (1) (18) 5 Total interest expense, net of amounts capitalized (620) (511) (1,812) (1,461) Gain (loss) on interest rate cash flow hedges (a) (22) (7) (31) (19) Gain (loss) on foreign currency cash flow hedges (a) (3) (3) (8) (16) Gain (loss) on interest rate fair value hedges (b) (47) (102) (50) (300) Total other income (expense), net 141 132 428 414 Gain (loss) on foreign currency cash flow hedges (a)(c) (14) (32) (4) (129) Gain (loss) on foreign currency fair value hedges (7) (59) 19 (180) Amount excluded from effectiveness testing recognized in earnings (27) (21) (28) (17) Southern Power Total depreciation and amortization $ 130 $ 133 $ 380 $ 384 Gain (loss) on energy-related cash flow hedges (a) (5) (1) (18) 5 Total interest expense, net of amounts capitalized (32) (32) (98) (105) Gain (loss) on foreign currency cash flow hedges (a) (3) (3) (8) (16) Total other income (expense), net 4 3 8 5 Gain (loss) on foreign currency cash flow hedges (a)(c) (14) (32) (4) (129) Southern Company Gas Total cost of natural gas $ 102 $ 294 $ 1,199 $ 1,840 Gain (loss) on energy-related cash flow hedges (a) (4) 9 (32) 28 Total other operations and maintenance 264 252 879 824 Gain (loss) on energy-related cash flow hedges (a) (1) — (2) — Total interest expense, net of amounts capitalized (77) (65) (226) (187) Gain (loss) on interest rate cash flow hedges (a) (18) (2) (18) (3) Gain (loss) on interest rate fair value hedges (b) (11) (30) (14) (87) (a) Reclassified from accumulated OCI into earnings. (b) For fair value hedges, changes in the fair value of the derivative contracts are generally equal to changes in the fair value of the underlying debt and have no material impact on income. (c) The reclassification from accumulated OCI into other income (expense), net completely offsets currency gains and losses arising from changes in the U.S. currency exchange rates used to record the euro-denominated notes. The pre-tax effects of cash flow and fair value hedge accounting on income for interest rate derivatives were immaterial for the traditional electric operating companies for all periods presented. At September 30, 2023 and December 31, 2022, the following amounts were recorded on the balance sheets related to cumulative basis adjustments for fair value hedges: Carrying Amount of the Hedged Item Cumulative Amount of Fair Value Hedging Adjustment included in Carrying Amount of the Hedged Item Balance Sheet Location of Hedged Items At September 30, 2023 At December 31, 2022 At September 30, 2023 At December 31, 2022 (in millions) (in millions) Southern Company Long-term debt $ (2,873) $ (2,927) $ 328 $ 282 Southern Company Gas Long-term debt $ (402) $ (415) $ 95 $ 81 For the three and nine months ended September 30, 2023 and 2022, the pre-tax effects of energy-related derivatives not designated as hedging instruments on the statements of income of Southern Company and Southern Company Gas were as follows: Gain (Loss) Three Months Ended September 30, Nine Months Ended September 30, Derivatives in Non-Designated Hedging Relationships Statements of Income Location 2023 2022 2023 2022 (in millions) (in millions) Energy-related derivatives: Natural gas revenues (*) $ — $ 3 $ — $ (10) Cost of natural gas 7 (2) 36 (7) Total derivatives in non-designated hedging relationships $ 7 $ 1 $ 36 $ (17) (*) Excludes $14 million of gains for the nine months ended September 30, 2023, and immaterial amounts for all other periods presented, recorded in natural gas revenues associated with weather derivatives. For the three and nine months ended September 30, 2023 and 2022, the pre-tax effects of energy-related derivatives not designated as hedging instruments were immaterial for the other Registrants. Contingent Features The Registrants do not have any credit arrangements that would require material changes in payment schedules or terminations as a result of a credit rating downgrade. There are certain derivatives that could require collateral, but not accelerated payment, in the event of various credit rating changes of certain Southern Company subsidiaries. Generally, collateral may be provided by a Southern Company guaranty, letter of credit, or cash. At September 30, 2023, the Registrants had no collateral posted with derivative counterparties to satisfy these arrangements. For Southern Company, the fair value of foreign currency derivative liabilities and interest rate derivative liabilities with contingent features, and the maximum potential collateral requirements arising from the credit-risk-related contingent features at a rating below BBB- and/or Baa3, was $78 million at September 30, 2023. For Southern Power, the fair value of foreign currency derivative liabilities with contingent features, and the maximum potential collateral requirements arising from the credit-risk-related contingent features at a rating below BBB- and/or Baa3, was $20 million at September 30, 2023. For the traditional electric operating companies and Southern Power, energy-related derivative liabilities with contingent features and the maximum potential collateral requirements arising from the credit-risk-related contingent features, at a rating below BBB- and/or Baa3, were immaterial at September 30, 2023. The maximum potential collateral requirements arising from the credit-risk-related contingent features for the traditional electric operating companies and Southern Power include certain agreements that could require collateral in the event that one or more Southern Company power pool participants has a credit rating change to below investment grade. Alabama Power and Southern Power maintain accounts with certain regional transmission organizations to facilitate financial derivative transactions and they may be required to post collateral based on the value of the positions in these accounts and the associated margin requirements. At September 30, 2023, cash collateral posted in these accounts was $18 million for Southern Power and immaterial for Alabama Power. Southern Company Gas maintains accounts with brokers or the clearing houses of certain exchanges to facilitate financial derivative transactions. Based on the value of the positions in these accounts and the associated margin requirements, Southern Company Gas may be required to deposit cash into these accounts. At September 30, 2023, cash collateral held on deposit in broker margin accounts was $49 million. The Registrants are exposed to losses related to financial instruments in the event of counterparties' nonperformance. The Registrants only enter into agreements and material transactions with counterparties that have investment grade credit ratings by Moody's and S&P or with counterparties who have posted collateral to cover potential credit exposure. The Registrants have also established risk management policies and controls to determine and monitor the creditworthiness of counterparties in order to mitigate their exposure to counterparty credit risk. Southern Company Gas uses established credit policies to determine and monitor the creditworthiness of counterparties, including requirements to post collateral or other credit security, as well as the quality of pledged collateral. Collateral or credit security is most often in the form of cash or letters of credit from an investment-grade financial institution, but may also include cash or U.S. government securities held by a trustee. Prior to entering a physical transaction, Southern Company Gas assigns its counterparties an internal credit rating and credit limit based on the counterparties' Moody's, S&P, and Fitch ratings, commercially available credit reports, and audited financial statements. Southern Company Gas may require counterparties to pledge additional collateral when deemed necessary. Southern Company Gas utilizes netting agreements whenever possible to mitigate exposure to counterparty credit risk. Netting agreements enable Southern Company Gas to net certain assets and liabilities by counterparty across product lines and against cash collateral, provided the netting and cash collateral agreements include such provisions. While the amounts due from, or owed to, counterparties are settled net, they are recorded on a gross basis on the balance sheet as energy marketing receivables and energy marketing payables. The Registrants do not anticipate a material adverse effect on their respective financial statements as a result of counterparty nonperformance.

Acquisitions and Dispositions

Acquisitions and Dispositions	9 Months Ended
	Sep. 30, 2023
Business Combination and Asset Acquisition [Abstract]
Acquisitions and Dispositions	ACQUISITIONS AND DISPOSITIONSSee Note 15 to the financial statements in Item 8 of the Form 10-K for additional information. Southern Power Asset Acquisitions Southern Power's asset acquisitions during the nine months ended September 30, 2023 are detailed in the following table: Project Facility Resource Seller Approximate Nameplate Capacity ( MW ) Location Southern Power Ownership Percentage Expected COD PPA Contract Period Millers Branch (*) Solar EDF Renewables, Inc. 200 Haskell County, TX 100% Fourth quarter 2025 20 years South Cheyenne Solar Hanwha Q Cells USA Corp. 150 Laramie County, WY 100% First quarter 2024 20 years (*) The project includes an option to expand capacity up to an additional 300 MWs. The aggregate purchase price for the two projects was $193 million, which is primarily recorded within construction work in progress on the balance sheet. Southern Company Gas On September 22, 2023, Southern Company Gas completed the sale of its California natural gas storage facility, resulting in an immaterial loss.

Segment and Related Information

Segment and Related Information	9 Months Ended
	Sep. 30, 2023
Segment Reporting [Abstract]
Segment and Related Information	SEGMENT AND RELATED INFORMATION Southern Company The primary businesses of the Southern Company system are electricity sales by the traditional electric operating companies and Southern Power and the distribution of natural gas by Southern Company Gas. The traditional electric operating companies are vertically integrated utilities providing electric service in three Southeastern states. Southern Power develops, constructs, acquires, owns, and manages power generation assets, including renewable energy and battery energy storage projects, and sells electricity at market-based rates in the wholesale market. Southern Company Gas distributes natural gas through its natural gas distribution utilities and is involved in several other complementary businesses including gas pipeline investments and gas marketing services. Southern Company's reportable business segments are the sale of electricity by the traditional electric operating companies, the sale of electricity in the competitive wholesale market by Southern Power, and the sale of natural gas and other complementary products and services by Southern Company Gas. Revenues from sales by Southern Power to the traditional electric operating companies were $156 million and $406 million for the three and nine months ended September 30, 2023, respectively, and $336 million and $673 million for the three and nine months ended September 30, 2022, respectively. Revenues from sales of natural gas from Southern Company Gas to the traditional electric operating companies and Southern Power were immaterial for all periods presented. The "All Other" column includes the Southern Company parent entity, which does not allocate operating expenses to business segments. Also, this category includes segments below the quantitative threshold for separate disclosure. These segments include providing distributed energy and resilience solutions and deploying microgrids for commercial, industrial, governmental, and utility customers, as well as investments in telecommunications. All other inter-segment revenues are not material. Financial data for business segments and products and services for the three and nine months ended September 30, 2023 and 2022 was as follows: Electric Utilities Traditional Southern Eliminations Total Southern Company Gas All Eliminations Consolidated (in millions) Three Months Ended September 30, 2023 Operating revenues $ 5,674 $ 653 $ (160) $ 6,167 $ 689 $ 154 $ (30) $ 6,980 Segment net income (loss) (a)(b)(c) 1,419 100 — 1,519 82 (179) — 1,422 Nine Months Ended September 30, 2023 Operating revenues $ 14,145 $ 1,686 $ (417) $ 15,414 $ 3,417 $ 499 $ (122) $ 19,208 Segment net income (loss) (a)(b)(c)(d) 2,852 288 — 3,140 475 (490) (4) 3,121 At September 30, 2023 Goodwill $ — $ 2 $ — $ 2 $ 5,015 $ 144 $ — $ 5,161 Total assets 99,464 13,090 (568) 111,986 24,823 2,370 (858) 138,321 Three Months Ended September 30, 2022 Operating revenues $ 6,938 $ 1,180 $ (691) $ 7,427 $ 857 $ 135 $ (41) $ 8,378 Segment net income (loss) (a)(b) 1,445 95 — 1,540 83 (152) 1 1,472 Nine Months Ended September 30, 2022 Operating revenues $ 16,716 $ 2,618 $ (1,391) $ 17,943 $ 3,998 $ 418 $ (127) $ 22,232 Segment net income (loss) (a)(b) 3,256 265 — 3,521 516 (415) (11) 3,611 At December 31, 2022 Goodwill $ — $ 2 $ — $ 2 $ 5,015 $ 144 $ — $ 5,161 Total assets 95,861 13,081 (659) 108,283 24,621 2,665 (678) 134,891 (a) Attributable to Southern Company. (b) For the traditional electric operating companies, includes pre-tax charges (credits) to income at Georgia Power for the estimated probable loss associated with the construction of Plant Vogtle Units 3 and 4 of $160 million ($120 million after tax) for the three and nine months ended September 30, 2023 and $(70) million ($(52) million after tax) and $(18) million ($(13) million after tax) for the three and nine months ended September 30, 2022, respectively. See Note (B) and Note 2 to the financial statements in Item 8 of the Form 10-K under "Georgia Power – Nuclear Construction" for additional information. (c) For Southern Power, includes an $18 million pre-tax loss recovery ($9 million after tax and partnership allocations) for the three and nine months ended September 30, 2023 related to an arbitration interim award and a $16 million pre-tax gain ($12 million after tax) on the sale of spare parts for the nine months ended September 30, 2023. See Note (C) under "General Litigation Matters – Southern Power" for additional information. (d) For Southern Company Gas, includes a pre-tax charge of approximately $38 million ($28 million after tax) associated with the disallowance of certain capital expenditures at Nicor Gas. See Note (B) under "Southern Company Gas" for additional information. Products and Services Electric Utilities' Revenues Retail Wholesale Other Total (in millions) Three Months Ended September 30, 2023 $ 5,139 $ 727 $ 301 $ 6,167 Three Months Ended September 30, 2022 5,961 1,197 269 7,427 Nine Months Ended September 30, 2023 $ 12,597 $ 1,930 $ 887 $ 15,414 Nine Months Ended September 30, 2022 14,363 2,798 782 17,943 Southern Company Gas' Revenues Gas Gas Other Total (in millions) Three Months Ended September 30, 2023 $ 617 $ 56 $ 16 $ 689 Three Months Ended September 30, 2022 748 85 24 857 Nine Months Ended September 30, 2023 $ 2,989 $ 376 $ 52 $ 3,417 Nine Months Ended September 30, 2022 3,513 420 65 3,998 Southern Company Gas Southern Company Gas manages its business through three reportable segments – gas distribution operations, gas pipeline investments, and gas marketing services. The non-reportable segments are combined and presented as all other. Gas distribution operations is the largest component of Southern Company Gas' business and includes natural gas local distribution utilities that construct, manage, and maintain intrastate natural gas pipelines and gas distribution facilities in four states. Gas pipeline investments consists of joint ventures in natural gas pipeline investments including a 50% interest in SNG and a 50% joint ownership interest in the Dalton Pipeline. These natural gas pipelines enable the provision of diverse sources of natural gas supplies to the customers of Southern Company Gas. See Note 7 to the financial statements under "Southern Company Gas" in Item 8 of the Form 10-K for additional information. Gas marketing services provides natural gas marketing to end-use customers primarily in Georgia and Illinois through SouthStar. The all other column includes segments and subsidiaries that fall below the quantitative threshold for separate disclosure, including storage and fuels operations. The all other column included a natural gas storage facility in Texas through its sale in November 2022 and a natural gas storage facility in California through its sale in September 2023. See Note 15 to the financial statements in Item 8 of the Form 10-K and Note (K) under "Southern Company Gas" for additional information. Business segment financial data for the three months ended September 30, 2023 and 2022 was as follows: Gas Distribution Operations Gas Gas Marketing Services Total All Other Eliminations Consolidated (in millions) Three Months Ended September 30, 2023 Operating revenues $ 619 $ 8 $ 56 $ 683 $ 8 $ (2) $ 689 Segment net income (loss) 70 24 2 96 (14) — 82 Nine Months Ended September 30, 2023 Operating revenues $ 3,002 $ 24 $ 376 $ 3,402 $ 30 $ (15) $ 3,417 Segment net income (*) 352 73 59 484 (9) — 475 Total assets at September 30, 2023 22,625 1,542 1,519 25,686 9,795 (10,658) 24,823 Three Months Ended September 30, 2022 Operating revenues $ 751 $ 8 $ 85 $ 844 $ 16 $ (3) $ 857 Segment net income (loss) 59 24 (2) 81 2 — 83 Nine Months Ended September 30, 2022 Operating revenues $ 3,533 $ 24 $ 420 $ 3,977 $ 43 $ (22) $ 3,998 Segment net income 365 76 65 506 10 — 516 Total assets at December 31, 2022 22,040 1,577 1,616 25,233 8,943 (9,555) 24,621 (*) For gas distribution operations, includes a pre-tax charge of approximately $38 million ($28 million after tax) associated with the disallowance of certain capital expenditures at Nicor Gas. See Note (B) under "Southern Company Gas" for additional information.

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Sep. 30, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Introduction (Policies)

Introduction (Policies)	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Accounting	The condensed quarterly financial statements of each Registrant included herein have been prepared by such Registrant, without audit, pursuant to the rules and regulations of the SEC. The Condensed Balance Sheets at December 31, 2022 have been derived from the audited financial statements of each Registrant. In the opinion of each Registrant's management, the information regarding such Registrant furnished herein reflects all adjustments, which, except as otherwise disclosed, are of a normal recurring nature, necessary to present fairly the results of operations for the periods ended September 30, 2023 and 2022. Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations, although each Registrant believes that the disclosures regarding such Registrant are adequate to make the information presented not misleading. Disclosures which would substantially duplicate the disclosures in the Form 10-K and details which have not changed significantly in amount or composition since the filing of the Form 10-K are generally omitted from this Quarterly Report on Form 10-Q unless specifically required by GAAP. Therefore, these Condensed Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the Form 10-K. Due to the seasonal variations in the demand for energy and other factors, operating results for the periods presented are not necessarily indicative of the operating results to be expected for the full year.
Reclassifications	Certain prior year data presented in the financial statements have been reclassified to conform to the current year presentation. These reclassifications had no impact on the overall results of operations, financial position, or cash flows of any Registrant.
Recently Adopted Accounting Standards	Recently Adopted Accounting Standards In March 2020 and December 2022, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting and ASU 2022-06, Reference Rate Reform (Topic 848): Deferral of the Sunset Date of Topic 848 , respectively, providing temporary guidance to ease the potential burden in accounting for reference rate reform primarily resulting from the discontinuation of LIBOR through December 31, 2024. See Note 1 to the financial statements under "Recently Adopted Accounting Standards" in Item 8 of the Form 10-K for additional information on the temporary guidance. Certain provisions in PPAs at Southern Power include references to LIBOR. Contract amendments have been executed to change to a SOFR-based interest rate. Southern Power adopted and applied the practical expedients guidance to these PPAs. Additionally, the Registrants referenced LIBOR for certain debt and hedging arrangements. As of July 1, 2023, all of the debt and hedging arrangements of the Registrants have transitioned to a SOFR-based interest rate based on the terms of the agreements. There were no material impacts from the transition to SOFR and no impacts to any existing accounting conclusions. See Note (J) under "Interest Rate Derivatives" for additional information.
Goodwill	Goodwill is not amortized, but is subject to an annual impairment test during the fourth quarter of each year, or more frequently if goodwill impairment indicators arise.
Natural Gas for Sale	Natural Gas for Sale With the exception of Nicor Gas, Southern Company Gas records natural gas inventories on a WACOG basis. For any declines in market prices below the WACOG considered to be other than temporary, an adjustment is recorded to reduce the value of natural gas inventories to market value. Nicor Gas' natural gas inventory is carried at cost on a LIFO basis. Inventory decrements occurring during the year that are restored prior to year-end are charged to cost of natural gas at the estimated annual replacement cost. Inventory decrements that are not restored prior to year-end are charged to cost of natural gas at the actual LIFO cost of the inventory layers liquidated.
Income Taxes	Income TaxesIn the third quarter 2023, Georgia Power started generating advanced nuclear PTCs for Plant Vogtle Unit 3 beginning on the in-service date of July 31, 2023. PTCs are recognized as an income tax benefit based on KWH production. In addition, pursuant to the Global Amendments to the Vogtle Joint Ownership Agreements (as defined in Note (B) under "Georgia Power – Nuclear Construction – Joint Owner Contracts"), Georgia Power is purchasing advanced nuclear PTCs for Plant Vogtle Unit 3 from certain other Vogtle Owners. The gain recognized on the purchase of the joint owner PTCs is recognized as an income tax benefit. See Note 1 to the financial statements under "Income Taxes" in Item 8 of the Form 10-K for additional information regarding accounting policies related to income taxes.
Valuation Methodologies	Valuation Methodologies The energy-related derivatives primarily consist of exchange-traded and over-the-counter financial products for natural gas and physical power products, including, from time to time, basis swaps. These are standard products used within the energy industry and are valued using the market approach. The inputs used are mainly from observable market sources, such as forward natural gas prices, power prices, implied volatility, and overnight index swap interest rates. Interest rate derivatives are also standard over-the-counter products that are valued using observable market data and assumptions commonly used by market participants. The fair value of interest rate derivatives reflects the net present value of expected payments and receipts under the swap agreement based on the market's expectation of future interest rates. Additional inputs to the net present value calculation may include the contract terms, counterparty credit risk, and occasionally, implied volatility of interest rate options. The fair value of cross-currency swaps reflects the net present value of expected payments and receipts under the swap agreement based on the market's expectation of future foreign currency exchange rates. Additional inputs to the net present value calculation may include the contract terms, counterparty credit risk, and discount rates. The interest rate derivatives and cross-currency swaps are categorized as Level 2 under Fair Value Measurements as these inputs are based on observable data and valuations of similar instruments. See Note (J) for additional information on how these derivatives are used. For fair value measurements of the investments within the nuclear decommissioning trusts and the non-qualified deferred compensation trusts, external pricing vendors are designated for each asset class with each security specifically assigned a primary pricing source. For investments held within commingled funds, fair value is determined at the end of each business day through the net asset value, which is established by obtaining the underlying securities' individual prices from the primary pricing source. A market price secured from the primary source vendor is then evaluated by management in its valuation of the assets within the trusts. As a general approach, fixed income market pricing vendors gather market data (including indices and market research reports) and integrate relative credit information, observed market movements, and sector news into proprietary pricing models, pricing systems, and mathematical tools. Dealer quotes and other market information, including live trading levels and pricing analysts' judgments, are also obtained when available. The NRC requires licensees of commissioned nuclear power reactors to establish a plan for providing reasonable assurance of funds for future decommissioning. See Note 6 to the financial statements under "Nuclear Decommissioning" in Item 8 of the Form 10-K for additional information. Southern Power has contingent payment obligations related to two of its acquisitions whereby it is primarily obligated to make generation-based payments to the seller, commencing at the commercial operation of each facility and continuing through 2026 and 2035, respectively. The obligations are primarily categorized as Level 3 under Fair Value Measurements as the fair value is determined using significant unobservable inputs for the forecasted facility's generation in MW-hours, as well as other inputs such as a fixed dollar amount per MW-hour, and a discount rate. The fair value of contingent consideration reflects the net present value of expected payments and any periodic change arising from forecasted generation is expected to be immaterial. Southern Power also has payment obligations through 2040 whereby it must reimburse the transmission owners for interconnection facilities and network upgrades constructed to support connection of a Southern Power generating facility to the transmission system. The obligations are categorized as Level 2 under Fair Value Measurements as the fair value is determined using observable inputs for the contracted amounts and reimbursement period, as well as a discount rate. The fair value of the obligations reflects the net present value of expected payments. "Other investments" primarily includes investments traded in the open market that have maturities greater than 90 days, which are categorized as Level 2 under Fair Value Measurements and are comprised of corporate bonds, bank certificates of deposit, treasury bonds, and/or agency bonds.
Derivatives	The Registrants are exposed to market risks, including commodity price risk, interest rate risk, weather risk, and occasionally foreign currency exchange rate risk. To manage the volatility attributable to these exposures, each company nets its exposures, where possible, to take advantage of natural offsets and enters into various derivative transactions for the remaining exposures pursuant to each company's policies in areas such as counterparty exposure and risk management practices. For the traditional electric operating companies, Southern Power, and Southern Company Gas' other businesses, each company's policy is that derivatives are to be used primarily for hedging purposes and mandates strict adherence to all applicable risk management policies. Derivative positions are monitored using techniques including, but not limited to, market valuation, value at risk, stress testing, and sensitivity analysis. Derivative instruments are recognized at fair value in the balance sheets as either assets or liabilities and are presented on a net basis. See Note (I) for additional fair value information. In the statements of cash flows, any cash impacts of settled energy-related and interest rate derivatives are recorded as operating activities. Any cash impacts of settled foreign currency derivatives are classified as operating or financing activities to correspond with the classification of the hedged interest or principal, respectively. See Note 1 to the financial statements under "Financial Instruments" in Item 8 of the Form 10-K for additional information. Energy-Related Derivatives The Subsidiary Registrants enter into energy-related derivatives to hedge exposures to electricity, natural gas, and other fuel price changes. However, due to cost-based rate regulations and other various cost recovery mechanisms, the traditional electric operating companies and the natural gas distribution utilities have limited exposure to market volatility in energy-related commodity prices. Each of the traditional electric operating companies and certain of the natural gas distribution utilities of Southern Company Gas manage fuel-hedging programs, implemented per the guidelines of their respective state PSCs or other applicable state regulatory agencies, through the use of financial derivative contracts, which are expected to continue to mitigate price volatility. The traditional electric operating companies (with respect to wholesale generating capacity) and Southern Power have limited exposure to market volatility in energy-related commodity prices because their long-term sales contracts shift substantially all fuel cost responsibility to the purchaser. However, the traditional electric operating companies and Southern Power may be exposed to market volatility in energy-related commodity prices to the extent any uncontracted capacity is used to sell electricity. Southern Company Gas retains exposure to price changes that can, in a volatile energy market, be material and can adversely affect its results of operations. Southern Company Gas also enters into weather derivative contracts as economic hedges in the event of warmer-than-normal weather. Exchange-traded options are carried at fair value, with changes reflected in operating revenues. Non-exchange-traded options are accounted for using the intrinsic value method. Changes in the intrinsic value for non-exchange-traded contracts are reflected in operating revenues. Energy-related derivative contracts are accounted for under one of three methods: • Regulatory Hedges – Energy-related derivative contracts designated as regulatory hedges relate primarily to the traditional electric operating companies' and the natural gas distribution utilities' fuel-hedging programs, where gains and losses are initially recorded as regulatory liabilities and assets, respectively, and then are included in fuel expense as the underlying fuel is used in operations and ultimately recovered through an approved cost recovery mechanism. • Cash Flow Hedges – Gains and losses on energy-related derivatives designated as cash flow hedges (which are mainly used to hedge anticipated purchases and sales) are initially deferred in accumulated OCI before being recognized in the statements of income in the same period and in the same income statement line item as the earnings effect of the hedged transactions. • Not Designated – Gains and losses on energy-related derivative contracts that are not designated or fail to qualify as hedges are recognized in the statements of income as incurred. Some energy-related derivative contracts require physical delivery as opposed to financial settlement, and this type of derivative is both common and prevalent within the electric and natural gas industries. When an energy-related derivative contract is settled physically, any cumulative unrealized gain or loss is reversed and the contract price is recognized in the respective line item representing the actual price of the underlying goods being delivered. Interest Rate Derivatives Southern Company and certain subsidiaries may enter into interest rate derivatives to hedge exposure to changes in interest rates. Derivatives related to existing variable rate securities or forecasted transactions are accounted for as cash flow hedges where the derivatives' fair value gains or losses are recorded in OCI and are reclassified into earnings at the same time and presented on the same income statement line item as the earnings effect of the hedged transactions. Derivatives related to existing fixed rate securities are accounted for as fair value hedges, where the derivatives' fair value gains or losses and hedged items' fair value gains or losses are both recorded directly to earnings on the same income statement line item. Fair value gains or losses on derivatives that are not designated or fail to qualify as hedges are recognized in the statements of income as incurred. Foreign Currency Derivatives Southern Company and certain subsidiaries, including Southern Power, may enter into foreign currency derivatives to hedge exposure to changes in foreign currency exchange rates, such as that arising from the issuance of debt denominated in a currency other than U.S. dollars. Derivatives related to forecasted transactions are accounted for as cash flow hedges where the derivatives' fair value gains or losses are recorded in OCI and are reclassified into earnings at the same time and on the same income statement line as the earnings effect of the hedged transactions, including foreign currency gains or losses arising from changes in the U.S. currency exchange rates. Derivatives related to existing fixed rate securities are accounted for as fair value hedges, where the derivatives' fair value gains or losses and hedged items' fair value gains or losses are both recorded directly to earnings on the same income statement line item, including foreign currency gains or losses arising from changes in the U.S. currency exchange rates. Southern Company has elected to exclude the cross-currency basis spread from the assessment of effectiveness in the fair value hedges of its foreign currency risk and record any difference between the change in the fair value of the excluded components and the amounts recognized in earnings as a component of OCI. Derivative Financial Statement Presentation and Amounts The Registrants enter into derivative contracts that may contain certain provisions that permit intra-contract netting of derivative receivables and payables for routine billing and offsets related to events of default and settlements. Southern Company and certain subsidiaries also utilize master netting agreements to mitigate exposure to counterparty credit risk. These agreements may contain provisions that permit netting across product lines and against cash collateral. The fair value amounts of derivative assets and liabilities on the balance sheets are presented net to the extent that there are netting arrangements or similar agreements with the counterparties.

Introduction (Tables)

Introduction (Tables)	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Goodwill	Goodwill at September 30, 2023 and December 31, 2022 was as follows: Goodwill (in millions) Southern Company $ 5,161 Southern Company Gas: Gas distribution operations $ 4,034 Gas marketing services 981 Southern Company Gas total $ 5,015
Schedule of Other Intangible Assets, Indefinite-Lived	Other intangible assets were as follows: At September 30, 2023 At December 31, 2022 Gross Carrying Amount Accumulated Amortization Other Gross Carrying Amount Accumulated Amortization Other (in millions) (in millions) Southern Company Subject to amortization: Customer relationships $ 211 $ (169) $ 42 $ 212 $ (162) $ 50 Trade names 63 (50) 13 64 (44) 20 PPA fair value adjustments 390 (143) 247 390 (129) 261 Other 5 (5) — 5 (5) — Total subject to amortization $ 669 $ (367) $ 302 $ 671 $ (340) $ 331 Not subject to amortization: FCC licenses 75 — 75 75 — 75 Total other intangible assets $ 744 $ (367) $ 377 $ 746 $ (340) $ 406 Southern Power (*) PPA fair value adjustments $ 390 $ (143) $ 247 $ 390 $ (129) $ 261 Southern Company Gas (*) Gas marketing services Customer relationships $ 156 $ (143) $ 13 $ 156 $ (139) $ 17 Trade names 26 (20) 6 26 (17) 9 Total other intangible assets $ 182 $ (163) $ 19 $ 182 $ (156) $ 26 (*) All subject to amortization.
Schedule of Other Intangible Assets, Finite-Lived	Other intangible assets were as follows: At September 30, 2023 At December 31, 2022 Gross Carrying Amount Accumulated Amortization Other Gross Carrying Amount Accumulated Amortization Other (in millions) (in millions) Southern Company Subject to amortization: Customer relationships $ 211 $ (169) $ 42 $ 212 $ (162) $ 50 Trade names 63 (50) 13 64 (44) 20 PPA fair value adjustments 390 (143) 247 390 (129) 261 Other 5 (5) — 5 (5) — Total subject to amortization $ 669 $ (367) $ 302 $ 671 $ (340) $ 331 Not subject to amortization: FCC licenses 75 — 75 75 — 75 Total other intangible assets $ 744 $ (367) $ 377 $ 746 $ (340) $ 406 Southern Power (*) PPA fair value adjustments $ 390 $ (143) $ 247 $ 390 $ (129) $ 261 Southern Company Gas (*) Gas marketing services Customer relationships $ 156 $ (143) $ 13 $ 156 $ (139) $ 17 Trade names 26 (20) 6 26 (17) 9 Total other intangible assets $ 182 $ (163) $ 19 $ 182 $ (156) $ 26 (*) All subject to amortization.
Schedule of Amortization of Other Intangible Assets	Amortization associated with other intangible assets was as follows: Three Months Ended Nine Months Ended Three Months Ended Nine Months Ended September 30, 2023 September 30, 2022 (in millions) Southern Company (a) $ 10 $ 27 $ 11 $ 30 Southern Power (b) 5 14 5 15 Southern Company Gas 3 7 4 9 (a) Includes $5 million, $14 million, $5 million, and $15 million for the three and nine months ended September 30, 2023 and 2022, respectively, recorded as a reduction to operating revenues. (b) Recorded as a reduction to operating revenues.
Schedule of Restrictions on Cash and Cash Equivalents	The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the condensed balance sheets that total to the amount shown in the condensed statements of cash flows for the applicable Registrants: Southern Company Alabama Power Georgia Power Southern Power Southern (in millions) At September 30, 2023 Cash and cash equivalents $ 1,676 $ 621 $ 173 $ 236 $ 397 Restricted cash (a) : Other current assets 176 108 48 18 2 Other deferred charges and assets 38 — 35 3 — Total cash, cash equivalents, and restricted cash (b) $ 1,890 $ 729 $ 256 $ 257 $ 399 At December 31, 2022 Cash and cash equivalents $ 1,917 $ 687 $ 364 $ 131 $ 81 Restricted cash (a) : Other current assets 62 — 60 — 2 Other deferred charges and assets 58 — 56 3 — Total cash, cash equivalents, and restricted cash (b) $ 2,037 $ 687 $ 480 $ 133 $ 83 (a) For Alabama Power, balance at September 30, 2023 reflects proceeds from the issuance of solid waste disposal facility revenue bonds in 2023. For Georgia Power, reflects proceeds from the issuance of solid waste disposal facility revenue bonds in 2022. For Southern Power, reflects $18 million at September 30, 2023 resulting from an arbitration interim award held to fund future replacement costs and $3 million at both September 30, 2023 and December 31, 2022 held to fund estimated construction completion costs at the Deuel Harvest wind facility. See Note (C) under "General Litigation Matters – Southern Power" for additional information. For Southern Company Gas, reflects collateral for workers' compensation, life insurance, and long-term disability insurance. (b) Total may not add due to rounding.
Schedule of Cash and Cash Equivalents	The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the condensed balance sheets that total to the amount shown in the condensed statements of cash flows for the applicable Registrants: Southern Company Alabama Power Georgia Power Southern Power Southern (in millions) At September 30, 2023 Cash and cash equivalents $ 1,676 $ 621 $ 173 $ 236 $ 397 Restricted cash (a) : Other current assets 176 108 48 18 2 Other deferred charges and assets 38 — 35 3 — Total cash, cash equivalents, and restricted cash (b) $ 1,890 $ 729 $ 256 $ 257 $ 399 At December 31, 2022 Cash and cash equivalents $ 1,917 $ 687 $ 364 $ 131 $ 81 Restricted cash (a) : Other current assets 62 — 60 — 2 Other deferred charges and assets 58 — 56 3 — Total cash, cash equivalents, and restricted cash (b) $ 2,037 $ 687 $ 480 $ 133 $ 83 (a) For Alabama Power, balance at September 30, 2023 reflects proceeds from the issuance of solid waste disposal facility revenue bonds in 2023. For Georgia Power, reflects proceeds from the issuance of solid waste disposal facility revenue bonds in 2022. For Southern Power, reflects $18 million at September 30, 2023 resulting from an arbitration interim award held to fund future replacement costs and $3 million at both September 30, 2023 and December 31, 2022 held to fund estimated construction completion costs at the Deuel Harvest wind facility. See Note (C) under "General Litigation Matters – Southern Power" for additional information. For Southern Company Gas, reflects collateral for workers' compensation, life insurance, and long-term disability insurance. (b) Total may not add due to rounding.
Schedule of Storm Damage Reserve Activity	Storm damage reserve activity for the traditional electric operating companies during the nine months ended September 30, 2023 was as follows: Southern Company (*) Alabama Power Georgia Power (*) Mississippi (in millions) Balance at December 31, 2022 $ 216 $ 97 $ 83 $ 36 Accrual 42 9 24 9 Weather-related damages (242) (35) (204) (3) Balance at September 30, 2023 $ 16 $ 71 $ (97) $ 42 (*) See Note (B) under "Georgia Power – Storm Damage Recovery" for additional information.
Schedule of Asset Retirement Obligations	The estimated costs of decommissioning Plant Farley based on Alabama Power's June 2023 site study are as follows: Plant Farley Decommissioning periods: Beginning year 2037 Completion year 2087 (in millions) Site study costs: Radiated structures $ 1,402 Spent fuel management 513 Non-radiated structures 133 Total site study costs $ 2,048

Regulatory Matters (Tables)

Regulatory Matters (Tables)	9 Months Ended
	Sep. 30, 2023
Regulated Operations [Abstract]
Schedule of Cost Recovery Clauses	The recovery balances for certain retail regulatory clauses of the traditional electric operating companies and Southern Company Gas at September 30, 2023 and December 31, 2022 were as follows: Regulatory Clause Balance Sheet Line Item September 30, December 31, 2022 (in millions) Alabama Power Rate CNP Compliance Other regulatory liabilities, deferred $ 3 $ — Other regulatory assets, current — 47 Rate CNP PPA Other regulatory assets, current 17 18 Other regulatory assets, deferred 90 102 Retail Energy Cost Recovery Other regulatory assets, current 208 102 Other regulatory assets, deferred 80 520 Georgia Power Fuel Cost Recovery (*) Receivables – under recovered fuel clause revenues $ 730 $ — Deferred under recovered fuel clause revenues 1,279 2,056 Mississippi Power Fuel Cost Recovery Receivables – customer accounts, net $ 25 $ 1 Ad Valorem Tax Other regulatory assets, current 3 12 Other regulatory assets, deferred 11 19 Southern Company Gas Natural Gas Cost Recovery Natural gas cost under recovery $ — $ 108 Natural gas cost over recovery 165 — (*) See "Georgia Power – Fuel Cost Recovery" herein for additional information.
Nuclear Construction Cost and Schedule	Georgia Power's approximate proportionate share of the remaining estimated capital cost to complete Plant Vogtle Units 3 and 4, including contingency, through July 2023 and March 2024, respectively, is as follows: (in millions) Base project capital cost forecast (a)(b) $ 10,736 Construction contingency estimate 17 Total project capital cost forecast (a)(b) 10,753 Net investment at September 30, 2023 (b) (10,495) Remaining estimate to complete $ 258 (a) Includes approximately $610 million of costs that are not shared with the other Vogtle Owners, including $33 million of construction monitoring costs approved for recovery by the Georgia PSC in its nineteenth VCM order, and approximately $567 million of incremental costs under the cost-sharing provisions of the joint ownership agreements described below. Excludes financing costs expected to be capitalized through AFUDC of approximately $420 million, of which $385 million had been accrued through September 30, 2023. (b) Net of $1.7 billion received from Toshiba under the Guarantee Settlement Agreement and approximately $188 million in related customer refunds.
Schedule of Infrastructure Replacement Programs and Capital Projects	Capital expenditures incurred under specific infrastructure replacement programs and capital projects during the first nine months of 2023 were as follows: Utility Program Nine Months Ended September 30, 2023 (in millions) Nicor Gas Investing in Illinois $ 320 Virginia Natural Gas SAVE 56 Atlanta Gas Light System Reinforcement Rider 84 Chattanooga Gas Pipeline Replacement Program 7 Total $ 467

Revenue from Contracts with C_2

Revenue from Contracts with Customers and Lease Income (Tables)	9 Months Ended
	Sep. 30, 2023
Revenue from Contract with Customer [Abstract]
Schedule of Disaggregation of Revenue	The following table disaggregates revenue from contracts with customers for the three and nine months ended September 30, 2023 and 2022: Southern Company Alabama Power Georgia Power Mississippi Power Southern Power Southern Company Gas (in millions) Three Months Ended September 30, 2023 Operating revenues Retail electric revenues Residential $ 2,543 $ 969 $ 1,473 $ 101 $ — $ — Commercial 1,845 599 1,151 95 — — Industrial 1,116 498 528 90 — — Other 30 3 25 2 — — Total retail electric revenues 5,534 2,069 3,177 288 — — Natural gas distribution revenues Residential 217 — — — — 217 Commercial 56 — — — — 56 Transportation 275 — — — — 275 Industrial 4 — — — — 4 Other 60 — — — — 60 Total natural gas distribution revenues 612 — — — — 612 Wholesale electric revenues PPA energy revenues 317 66 31 2 226 — PPA capacity revenues 151 26 13 3 110 — Non-PPA revenues 101 15 21 137 126 — Total wholesale electric revenues 569 107 65 142 462 — Other natural gas revenues Gas marketing services 54 — — — — 54 Other natural gas revenues 8 — — — — 8 Total natural gas revenues 62 — — — — 62 Other revenues 330 54 146 10 18 — Total revenue from contracts with customers 7,107 2,230 3,388 440 480 674 Other revenue sources (*) (127) (147) (151) (4) 173 15 Total operating revenues $ 6,980 $ 2,083 $ 3,237 $ 436 $ 653 $ 689 Southern Company Alabama Power Georgia Power Mississippi Power Southern Power Southern Company Gas (in millions) Nine Months Ended September 30, 2023 Operating revenues Retail electric revenues Residential $ 5,717 $ 2,277 $ 3,202 $ 238 $ — $ — Commercial 4,464 1,493 2,733 238 — — Industrial 2,770 1,324 1,195 251 — — Other 84 10 68 6 — — Total retail electric revenues 13,035 5,104 7,198 733 — — Natural gas distribution revenues Residential 1,443 — — — — 1,443 Commercial 370 — — — — 370 Transportation 878 — — — — 878 Industrial 33 — — — — 33 Other 228 — — — — 228 Total natural gas distribution revenues 2,952 — — — — 2,952 Wholesale electric revenues PPA energy revenues 853 196 66 8 601 — PPA capacity revenues 490 130 38 36 289 — Non-PPA revenues 199 49 30 315 312 — Total wholesale electric revenues 1,542 375 134 359 1,202 — Other natural gas revenues Gas marketing services 358 — — — — 358 Other natural gas revenues 28 — — — — 28 Total natural gas revenues 386 — — — — 386 Other revenues 971 159 422 31 46 — Total revenue from contracts with customers 18,886 5,638 7,754 1,123 1,248 3,338 Other revenue sources (*) 322 (218) 51 14 438 79 Total operating revenues $ 19,208 $ 5,420 $ 7,805 $ 1,137 $ 1,686 $ 3,417 Southern Company Alabama Power Georgia Power Mississippi Power Southern Power Southern Company Gas (in millions) Three Months Ended September 30, 2022 Operating revenues Retail electric revenues Residential $ 2,104 $ 799 $ 1,212 $ 93 $ — $ — Commercial 1,637 499 1,051 87 — — Industrial 1,183 452 642 89 — — Other 27 3 22 2 — — Total retail electric revenues 4,951 1,753 2,927 271 — — Natural gas distribution revenues Residential 331 — — — — 331 Commercial 93 — — — — 93 Transportation 259 — — — — 259 Industrial 12 — — — — 12 Other 49 — — — — 49 Total natural gas distribution revenues 744 — — — — 744 Wholesale electric revenues PPA energy revenues 812 187 40 4 591 — PPA capacity revenues 175 56 12 1 107 — Non-PPA revenues 58 67 4 242 303 — Total wholesale electric revenues 1,045 310 56 247 1,001 — Other natural gas revenues Gas marketing services 84 — — — — 84 Other natural gas revenues 15 — — — — 15 Total natural gas revenues 99 — — — — 99 Other revenues 277 65 110 13 9 — Total revenue from contracts with customers 7,116 2,128 3,093 531 1,010 843 Other revenue sources (*) 1,262 316 796 (21) 170 14 Total operating revenues $ 8,378 $ 2,444 $ 3,889 $ 510 $ 1,180 $ 857 Southern Company Alabama Power Georgia Power Mississippi Power Southern Power Southern Company Gas (in millions) Nine Months Ended September 30, 2022 Operating revenues Retail electric revenues Residential $ 5,282 $ 2,049 $ 2,995 $ 238 $ — $ — Commercial 4,202 1,285 2,688 229 — — Industrial 2,914 1,143 1,529 242 — — Other 79 10 62 7 — — Total retail electric revenues 12,477 4,487 7,274 716 — — Natural gas distribution revenues Residential 1,821 — — — — 1,821 Commercial 493 — — — — 493 Transportation 872 — — — — 872 Industrial 60 — — — — 60 Other 244 — — — — 244 Total natural gas distribution revenues 3,490 — — — — 3,490 Wholesale electric revenues PPA energy revenues 1,739 354 112 11 1,285 — PPA capacity revenues 443 135 35 4 273 — Non-PPA revenues 182 166 19 511 572 — Total wholesale electric revenues 2,364 655 166 526 2,130 — Other natural gas revenues Gas marketing services 417 — — — — 417 Other natural gas revenues 41 — — — — 41 Total natural gas revenues 458 — — — — 458 Other revenues 810 173 327 34 27 — Total revenue from contracts with customers 19,599 5,315 7,767 1,276 2,157 3,948 Other revenue sources (*) 2,633 708 1,451 3 461 50 Total operating revenues $ 22,232 $ 6,023 $ 9,218 $ 1,279 $ 2,618 $ 3,998 (*) Other revenue sources relate to revenues from customers accounted for as derivatives and leases, alternative revenue programs at Southern Company Gas, and cost recovery mechanisms and revenues (including those related to fuel costs) that meet other scope exceptions for revenues from contracts with customers at the traditional electric operating companies.
Schedule of Contract Balances	The following table reflects the closing balances of receivables, contract assets, and contract liabilities related to revenues from contracts with customers at September 30, 2023 and December 31, 2022: Southern Company Alabama Power Georgia Power Mississippi Power Southern Power Southern Company Gas (in millions) Accounts Receivable At September 30, 2023 $ 2,680 $ 858 $ 1,175 $ 106 $ 138 $ 331 At December 31, 2022 3,123 696 922 92 237 1,107 Contract Assets At September 30, 2023 $ 267 $ 6 $ 146 $ — $ — $ 41 At December 31, 2022 156 2 89 — — — Contract Liabilities At September 30, 2023 $ 62 $ — $ 8 $ 2 $ 8 $ — At December 31, 2022 45 4 9 — 1 —
Schedule of Remaining Performance Obligations	Revenues from contracts with customers related to these performance obligations remaining at September 30, 2023 are expected to be recognized as follows: 2023 (remaining) 2024 2025 2026 2027 Thereafter (in millions) Southern Company $ 166 $ 599 $ 359 $ 318 $ 319 $ 2,245 Alabama Power 10 24 8 — — — Georgia Power 23 66 34 14 14 23 Southern Power 84 356 302 303 310 2,233 Southern Company Gas 4 29 — — — —
Schedule of Lease Income	Lease income for the three and nine months ended September 30, 2023 and 2022 is as follows: Southern Alabama Power Georgia Power Mississippi Southern Power Southern Company Gas (in millions) For the Three Months Ended September 30, 2023 Lease income - interest income on sales-type leases $ 6 $ — $ — $ 4 $ 2 $ — Lease income - operating leases 36 3 7 — 21 9 Variable lease income 134 — — — 144 — Total lease income $ 176 $ 3 $ 7 $ 4 $ 167 $ 9 For the Nine Months Ended September 30, 2023 Lease income - interest income on sales-type leases $ 18 $ — $ — $ 11 $ 7 $ — Lease income - operating leases 129 32 22 2 64 27 Variable lease income 327 1 — — 351 — Total lease income $ 474 $ 33 $ 22 $ 13 $ 422 $ 27 For the Three Months Ended September 30, 2022 Lease income - interest income on sales-type leases $ 7 $ — $ — $ 4 $ 3 $ — Lease income - operating leases 50 19 8 1 21 9 Variable lease income 139 — — — 145 — Total lease income $ 196 $ 19 $ 8 $ 5 $ 169 $ 9 For the Nine Months Ended September 30, 2022 Lease income - interest income on sales-type leases $ 19 $ — $ — $ 11 $ 8 $ — Lease income - operating leases 149 58 24 1 64 27 Variable lease income 355 1 — — 372 — Total lease income $ 523 $ 59 $ 24 $ 12 $ 444 $ 27

Consolidated Entities and Equ_2

Consolidated Entities and Equity Method Investments (Tables)	9 Months Ended
	Sep. 30, 2023
Regulated Operations [Abstract]
Schedule of Equity Method Investments	The carrying amounts of Southern Company Gas' equity method investments at September 30, 2023 and December 31, 2022 and related earnings from those investments for the three and nine months ended September 30, 2023 and 2022 were as follows: Investment Balance September 30, 2023 December 31, 2022 (in millions) SNG $ 1,210 $ 1,243 Other 33 33 Total $ 1,243 $ 1,276
Schedule of Earnings (Loss) from Equity Method Investments	Three Months Ended September 30, Nine Months Ended September 30, Earnings from Equity Method Investments 2023 2022 2023 2022 (in millions) SNG $ 32 $ 34 $ 104 $ 104 Other — — — 1 Total $ 32 $ 34 $ 104 $ 105

Financing and Leases (Tables)

Financing and Leases (Tables)	9 Months Ended
	Sep. 30, 2023
Debt Disclosure [Abstract]
Schedule of Credit Arrangements	At September 30, 2023, committed credit arrangements with banks were as follows: Expires Company 2024 2025 2026 2028 Total Unused Expires within (in millions) Southern Company parent (a) $ 150 $ — $ — $ 1,850 $ 2,000 $ 1,998 $ 150 Alabama Power — — 650 700 1,350 1,350 — Georgia Power — — — 1,750 1,750 1,726 — Mississippi Power — 125 150 — 275 275 — Southern Power (a)(b) — — — 600 600 589 — Southern Company Gas (c) 100 — — 1,500 1,600 1,598 100 SEGCO 30 — — — 30 30 30 Southern Company $ 280 $ 125 $ 800 $ 6,400 $ 7,605 $ 7,566 $ 280 (a) Arrangement expiring in 2028 represents a $2.45 billion combined arrangement for Southern Company and Southern Power as borrowers. Pursuant to the combined facility, the allocations between Southern Company and Southern Power may be adjusted. (b) Does not include Southern Power Company's $75 million and $100 million continuing letter of credit facilities for standby letters of credit, expiring in 2025 and 2026, respectively, of which $9 million and $16 million, respectively, was unused at September 30, 2023. In March 2023, Southern Power amended the $100 million letter of credit facility, which, among other things, extended the expiration date from 2025 to 2026 and increased the amount from $75 million. Southern Power's subsidiaries are not parties to its bank credit arrangements or letter of credit facilities. (c) Southern Company Gas, as the parent entity, guarantees the obligations of Southern Company Gas Capital, which is the borrower of $800 million of the credit arrangement expiring in 2028. Southern Company Gas' committed credit arrangement expiring in 2028 also includes $700 million for which Nicor Gas is the borrower and which is restricted for working capital needs of Nicor Gas. Pursuant to the multi-year credit arrangement expiring in 2028, the allocations between Southern Company Gas Capital and Nicor Gas may be adjusted. Nicor Gas is also the borrower under a $100 million credit arrangement expiring in 2024.
Schedule of Shares Used to Compute Diluted Earnings Per Share	Shares used to compute diluted EPS were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 (in millions) As reported shares 1,092 1,082 1,092 1,070 Effect of stock-based compensation 7 6 6 6 Diluted shares 1,099 1,088 1,098 1,076

Retirement Benefits (Tables)

Retirement Benefits (Tables)	9 Months Ended
	Sep. 30, 2023
Retirement Benefits [Abstract]
Schedule of Pension Plans and Postretirement Plans	Components of the net periodic benefit costs for the three and nine months ended September 30, 2023 and 2022 are presented in the following tables. Southern Alabama Georgia Mississippi Southern Power Southern Company Gas (in millions) Three Months Ended September 30, 2023 Pension Plans Service cost $ 69 $ 16 $ 17 $ 2 $ 2 $ 6 Interest cost 156 37 48 7 2 11 Expected return on plan assets (307) (75) (97) (13) (4) (22) Amortization: Prior service costs — — — — — (1) Regulatory asset — — — — — 4 Net (gain) loss 8 2 4 1 — (1) Net periodic pension income $ (74) $ (20) $ (28) $ (3) $ — $ (3) Postretirement Benefits Service cost $ 4 $ 1 $ 1 $ — $ — $ — Interest cost 18 5 6 1 — 2 Expected return on plan assets (21) (9) (7) (1) — (2) Amortization: Prior service costs — — 1 — — — Regulatory asset — — — — — 2 Net gain (4) (1) (1) — — (1) Net periodic postretirement benefit cost (income) $ (3) $ (4) $ — $ — $ — $ 1 Nine Months Ended September 30, 2023 Pension Plans Service cost $ 207 $ 48 $ 51 $ 8 $ 5 $ 18 Interest cost 469 109 143 21 6 32 Expected return on plan assets (922) (223) (289) (41) (12) (65) Amortization: Prior service costs — — 1 — — (2) Regulatory asset — — — — — 11 Net (gain) loss 24 7 10 1 — (3) Net periodic pension income $ (222) $ (59) $ (84) $ (11) $ (1) $ (9) Postretirement Benefits Service cost $ 11 $ 3 $ 3 $ — $ — $ 1 Interest cost 53 13 19 2 — 6 Expected return on plan assets (62) (26) (22) (1) — (5) Amortization: Prior service costs 1 — 1 — — — Regulatory asset — — — — — 5 Net gain (10) (2) (3) — — (3) Net periodic postretirement benefit cost (income) $ (7) $ (12) $ (2) $ 1 $ — $ 4 Southern Alabama Georgia Mississippi Southern Power Southern Company Gas (in millions) Three Months Ended September 30, 2022 Pension Plans Service cost $ 103 $ 25 $ 26 $ 5 $ 2 $ 9 Interest cost 102 24 31 5 2 7 Expected return on plan assets (316) (77) (99) (15) (4) (22) Amortization: Prior service costs — — — — — (1) Regulatory asset — — — — — 3 Net loss 60 16 18 2 1 2 Net periodic pension cost (income) $ (51) $ (12) $ (24) $ (3) $ 1 $ (2) Postretirement Benefits Service cost $ 6 $ 2 $ 2 $ 1 $ 1 $ — Interest cost 10 3 4 — — 1 Expected return on plan assets (20) (9) (8) — — (2) Amortization: Prior service costs (1) — — — — — Regulatory asset — — — — — 2 Net (gain)/loss 1 — — — — (1) Net periodic postretirement benefit cost (income) $ (4) $ (4) $ (2) $ 1 $ 1 $ — Nine Months Ended September 30, 2022 Pension Plans Service cost $ 309 $ 74 $ 78 $ 13 $ 7 $ 26 Interest cost 306 72 92 14 5 21 Expected return on plan assets (949) (229) (298) (44) (12) (68) Amortization: Prior service costs — — 1 — — (2) Regulatory asset — — — — — 11 Net loss 180 47 55 9 2 5 Net periodic pension cost (income) $ (154) $ (36) $ (72) $ (8) $ 2 $ (7) Postretirement Benefits Service cost $ 17 $ 5 $ 5 $ 1 $ 1 $ 1 Interest cost 31 8 11 1 — 4 Expected return on plan assets (60) (25) (21) (1) — (6) Amortization: Prior service costs (1) — — — — — Regulatory asset — — — — — 5 Net (gain) loss 1 — 1 — — (2) Net periodic postretirement benefit cost (income) $ (12) $ (12) $ (4) $ 1 $ 1 $ 2

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Schedule of Assets and Liabilities Measured at Fair Value	At September 30, 2023, assets and liabilities measured at fair value on a recurring basis during the period, together with their associated level of the fair value hierarchy, were as follows: Fair Value Measurements Using: At September 30, 2023 Quoted Prices Significant Significant Net Asset Value as a Practical Expedient (NAV) Total (in millions) Southern Company Assets: Energy-related derivatives (a) $ 7 $ 73 $ — $ — $ 80 Investments in trusts: (b) Domestic equity 692 196 — — 888 Foreign equity 131 154 — — 285 U.S. Treasury and government agency securities — 337 — — 337 Municipal bonds — 42 — — 42 Pooled funds – fixed income — 6 — — 6 Corporate bonds — 368 — — 368 Mortgage and asset backed securities — 85 — — 85 Private equity — — — 169 169 Cash and cash equivalents 3 — — — 3 Other 33 3 — 8 44 Cash equivalents and restricted cash 919 11 — — 930 Other investments 9 34 8 — 51 Total $ 1,794 $ 1,309 $ 8 $ 177 $ 3,288 Liabilities: Energy-related derivatives (a) $ 34 $ 217 $ — $ — $ 251 Interest rate derivatives — 351 — — 351 Foreign currency derivatives — 192 — — 192 Contingent consideration 5 — 19 — 24 Other — 13 — — 13 Total $ 39 $ 773 $ 19 $ — $ 831 Fair Value Measurements Using: At September 30, 2023 Quoted Prices Significant Significant Net Asset Value as a Practical Expedient (NAV) Total (in millions) Alabama Power Assets: Energy-related derivatives $ — $ 26 $ — $ — $ 26 Nuclear decommissioning trusts: (b) Domestic equity 404 188 — — 592 Foreign equity 131 — — — 131 U.S. Treasury and government agency securities — 20 — — 20 Municipal bonds — 1 — — 1 Corporate bonds — 215 — — 215 Mortgage and asset backed securities — 22 — — 22 Private equity — — — 169 169 Other 10 — — 8 18 Cash equivalents and restricted cash 489 11 — — 500 Other investments — 34 — — 34 Total $ 1,034 $ 517 $ — $ 177 $ 1,728 Liabilities: Energy-related derivatives $ — $ 75 $ — $ — $ 75 Georgia Power Assets: Energy-related derivatives $ — $ 14 $ — $ — $ 14 Nuclear decommissioning trusts: (b) Domestic equity 288 1 — — 289 Foreign equity — 153 — — 153 U.S. Treasury and government agency securities — 317 — — 317 Municipal bonds — 41 — — 41 Corporate bonds — 153 — — 153 Mortgage and asset backed securities — 63 — — 63 Other 23 3 — — 26 Total $ 311 $ 745 $ — $ — $ 1,056 Liabilities: Energy-related derivatives $ — $ 83 $ — $ — $ 83 Fair Value Measurements Using: At September 30, 2023 Quoted Prices Significant Significant Net Asset Value as a Practical Expedient (NAV) Total (in millions) Mississippi Power Assets: Energy-related derivatives $ — $ 24 $ — $ — $ 24 Cash equivalents 3 — — — 3 Total $ 3 $ 24 $ — $ — $ 27 Liabilities: Energy-related derivatives $ — $ 44 $ — $ — $ 44 Southern Power Assets: Energy-related derivatives $ — $ 5 $ — $ — $ 5 Cash equivalents 23 — — — 23 Total $ 23 $ 5 $ — $ — $ 28 Liabilities: Energy-related derivatives $ — $ 6 $ — $ — $ 6 Foreign currency derivatives — 42 — — 42 Contingent consideration 5 — 19 — 24 Other — 13 — — 13 Total $ 5 $ 61 $ 19 $ — $ 85 Southern Company Gas Assets: Energy-related derivatives (a) $ 7 $ 4 $ — $ — $ 11 Non-qualified deferred compensation trusts: Domestic equity — 7 — — 7 Foreign equity — 1 — — 1 Pooled funds – fixed income — 6 — — 6 Cash equivalents 3 — — — 3 Cash equivalents 294 — — — 294 Total $ 304 $ 18 $ — $ — $ 322 Liabilities: Energy-related derivatives (a) $ 34 $ 9 $ — $ — $ 43 Interest rate derivatives — 99 — — 99 Total $ 34 $ 108 $ — $ — $ 142 (a) Excludes cash collateral of $49 million. (b) Excludes receivables related to investment income, pending investment sales, payables related to pending investment purchases, and currencies. See Note 6 to the financial statements in Item 8 of the Form 10-K for additional information.
Schedule of Increase (Decrease) In Fair Value Of Funds	The changes were recorded as a change to the regulatory assets and liabilities related to AROs for Georgia Power and Alabama Power, respectively. Three Months Ended Nine Months Ended Fair value increases (decreases) September 30, 2023 September 30, 2022 September 30, 2023 September 30, 2022 (in millions) Southern Company $ (4) $ (106) $ 211 $ (486) Alabama Power (36) (53) 54 (245) Georgia Power 32 (53) 157 (241)
Schedule of Financial Instruments for which Carrying Amount Did Not Equal Fair Value	At September 30, 2023, other financial instruments for which the carrying amount did not equal fair value were as follows: Southern Company (*) Alabama Power Georgia Power Mississippi Power Southern Power Southern Company Gas (*) (in billions) Long-term debt, including securities due within one year: Carrying amount $ 58.8 $ 11.2 $ 15.8 $ 1.6 $ 2.7 $ 8.1 Fair value 50.8 9.4 13.4 1.3 2.4 6.5 (*) The carrying amount of Southern Company Gas' long-term debt includes fair value adjustments from the effective date of the 2016 merger with Southern Company. Southern Company Gas amortizes the fair value adjustments over the remaining lives of the respective bonds, the latest being through 2043.

Derivatives (Tables)

Derivatives (Tables)	9 Months Ended
	Sep. 30, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Energy-Related Derivatives	At September 30, 2023, the net volume of energy-related derivative contracts for natural gas positions, together with the longest hedge date over which the respective entity is hedging its exposure to the variability in future cash flows for forecasted transactions and the longest non-hedge date for derivatives not designated as hedges, were as follows: Net Longest Longest (in millions) Southern Company (*) 422 2030 2028 Alabama Power 109 2026 — Georgia Power 104 2026 — Mississippi Power 80 2027 — Southern Power 8 2030 2024 Southern Company Gas (*) 121 2027 2028 (*) Southern Company Gas' derivative instruments include both long and short natural gas positions. A long position is a contract to purchase natural gas and a short position is a contract to sell natural gas. Southern Company Gas' volume represents the net of 135.5 million mmBtu long natural gas positions and 14.2 million mmBtu short natural gas positions at September 30, 2023, which is also included in Southern Company's total volume.
Schedule of Interest Rate Derivatives	At September 30, 2023, the following interest rate derivatives were outstanding: Notional Weighted Interest Hedge Fair Value Gain (Loss) at September 30, 2023 (in millions) (in millions) Fair Value Hedges of Existing Debt Southern Company parent $ 400 1-month SOFR + 0.80% 1.75% March 2028 $ (56) Southern Company parent 1,000 1-month SOFR + 2.48% 3.70% April (196) Southern Company Gas 500 1-month SOFR + 0.49% 1.75% January 2031 (99) Southern Company $ 1,900 $ (351)
Schedule of Foreign Currency Derivatives	At September 30, 2023, the following foreign currency derivatives were outstanding: Pay Notional Pay Receive Notional Receive Hedge Fair Value Gain (Loss) at September 30, 2023 (in millions) (in millions) (in millions) Cash Flow Hedges of Existing Debt Southern Power $ 564 3.78% € 500 1.85% June 2026 $ (42) Fair Value Hedges of Existing Debt Southern Company parent 1,476 3.39% 1,250 1.88% September 2027 (150) Southern Company $ 2,040 € 1,750 $ (192)
Schedule of Derivative Category and Balance Sheet Location	The fair value of energy-related derivatives, interest rate derivatives, and foreign currency derivatives was reflected in the balance sheets as follows: At September 30, 2023 At December 31, 2022 Derivative Category and Balance Sheet Location Assets Liabilities Assets Liabilities (in millions) (in millions) Southern Company Energy-related derivatives designated as hedging instruments for regulatory purposes Assets from risk management activities/Liabilities from risk management activities $ 34 $ 134 $ 123 $ 121 Other deferred charges and assets/Other deferred credits and liabilities 36 77 52 44 Total derivatives designated as hedging instruments for regulatory purposes 70 211 175 165 Derivatives designated as hedging instruments in cash flow and fair value hedges Energy-related derivatives: Assets from risk management activities/Liabilities from risk management activities — 28 3 27 Other deferred charges and assets/Other deferred credits and liabilities 4 2 6 4 Interest rate derivatives: Assets from risk management activities/Liabilities from risk management activities — 80 12 62 Other deferred charges and assets/Other deferred credits and liabilities — 271 — 240 Foreign currency derivatives: Assets from risk management activities/Liabilities from risk management activities — 35 — 34 Other deferred charges and assets/Other deferred credits and liabilities — 157 — 182 Total derivatives designated as hedging instruments in cash flow and fair value hedges 4 573 21 549 Energy-related derivatives not designated as hedging instruments Assets from risk management activities/Liabilities from risk management activities 5 8 13 13 Other deferred charges and assets/Other deferred credits and liabilities 1 2 2 1 Total derivatives not designated as hedging instruments 6 10 15 14 Gross amounts recognized 80 794 211 728 Gross amounts offset (a) (37) (86) (70) (111) Net amounts recognized in the Balance Sheets (b) $ 43 $ 708 $ 141 $ 617 At September 30, 2023 At December 31, 2022 Derivative Category and Balance Sheet Location Assets Liabilities Assets Liabilities (in millions) (in millions) Alabama Power (c) Energy-related derivatives designated as hedging instruments for regulatory purposes Other current assets/Other current liabilities $ 15 $ 46 $ 42 $ 21 Other deferred charges and assets/Other deferred credits and liabilities 11 29 20 18 Total derivatives designated as hedging instruments for regulatory purposes 26 75 62 39 Gross amounts offset (17) (17) (24) (24) Net amounts recognized in the Balance Sheets $ 9 $ 58 $ 38 $ 15 Georgia Power Energy-related derivatives designated as hedging instruments for regulatory purposes Other current assets/Other current liabilities $ 4 $ 57 $ 36 $ 43 Other deferred charges and assets/Other deferred credits and liabilities 10 26 6 18 Total derivatives designated as hedging instruments for regulatory purposes 14 83 42 61 Energy-related derivatives not designated as hedging instruments Other current assets/Other current liabilities — — — 1 Gross amounts recognized 14 83 42 62 Gross amounts offset (11) (11) (21) (21) Net amounts recognized in the Balance Sheets $ 3 $ 72 $ 21 $ 41 Mississippi Power (c) Energy-related derivatives designated as hedging instruments for regulatory purposes Other current assets/Other current liabilities $ 9 $ 22 $ 33 $ 24 Other deferred charges and assets/Other deferred credits and liabilities 15 22 26 8 Total derivatives designated as hedging instruments for regulatory purposes 24 44 59 32 Gross amounts offset (17) (17) (17) (17) Net amounts recognized in the Balance Sheets $ 7 $ 27 $ 42 $ 15 At September 30, 2023 At December 31, 2022 Derivative Category and Balance Sheet Location Assets Liabilities Assets Liabilities (in millions) (in millions) Southern Power Derivatives designated as hedging instruments in cash flow and fair value hedges Energy-related derivatives: Other current assets/Other current liabilities $ — $ 5 $ — $ 12 Other deferred charges and assets/Other deferred credits and liabilities 4 — 5 — Foreign currency derivatives: Other current assets/Other current liabilities — 11 — 11 Other deferred charges and assets/Other deferred credits and liabilities — 31 — 36 Total derivatives designated as hedging instruments in cash flow and fair value hedges 4 47 5 59 Energy-related derivatives not designated as hedging instruments Other current assets/Other current liabilities 1 1 2 — Other deferred charges and assets/Other deferred credits and liabilities — — 1 — Total derivatives not designated as hedging instruments 1 1 3 — Gross amounts recognized 5 48 8 59 Gross amounts offset (1) (1) — — Net amounts recognized in the Balance Sheets $ 4 $ 47 $ 8 $ 59 Southern Company Gas Energy-related derivatives designated as hedging instruments for regulatory purposes Other current assets/Other current liabilities $ 6 $ 9 $ 12 $ 33 Derivatives designated as hedging instruments in cash flow and fair value hedges Energy-related derivatives: Other current assets/Other current liabilities — 23 3 15 Other deferred charges and assets/Other deferred credits and liabilities — 2 1 4 Interest rate derivatives: Other current assets/Other current liabilities — 21 — 14 Other deferred charges and assets/Other deferred credits and liabilities — 78 — 72 Total derivatives designated as hedging instruments in cash flow and fair value hedges — 124 4 105 Energy-related derivatives not designated as hedging instruments Other current assets/Other current liabilities 4 7 11 12 Other deferred charges and assets/Other deferred credits and liabilities 1 2 1 1 Total derivatives not designated as hedging instruments 5 9 12 13 Gross amounts recognized 11 142 28 151 Gross amounts offset (a) 9 (40) — (41) Net amounts recognized in the Balance Sheets (b) $ 20 $ 102 $ 28 $ 110 (a) Gross amounts offset includes cash collateral held on deposit in broker margin accounts of $49 million and $41 million at September 30, 2023 and December 31, 2022, respectively. (b) Net amounts of derivative instruments outstanding exclude immaterial premium and intrinsic value associated with weather derivatives for both periods presented. (c) Energy-related derivatives not designated as hedging instruments were immaterial for Alabama Power and Mississippi Power at December 31, 2022. There were no such instruments for Alabama Power and Mississippi Power at September 30, 2023.
Schedule of Pre-tax Effects of Unrealized Derivative Gains (Losses)	At September 30, 2023 and December 31, 2022, the pre-tax effects of unrealized derivative gains (losses) arising from energy-related derivative instruments designated as regulatory hedging instruments and deferred were as follows: Regulatory Hedge Unrealized Gain (Loss) Recognized in the Balance Sheet Derivative Category and Balance Sheet Southern Alabama Georgia Mississippi Southern Company Gas (in millions) At September 30, 2023: Energy-related derivatives: Other regulatory assets, current $ (113) $ (39) $ (54) $ (16) $ (4) Other regulatory assets, deferred (48) (19) (18) (11) — Other regulatory liabilities, current 23 8 1 4 10 Other regulatory liabilities, deferred 6 1 2 3 — Total energy-related derivative gains (losses) $ (132) $ (49) $ (69) $ (20) $ 6 At December 31, 2022: Energy-related derivatives: Other regulatory assets, current $ (71) $ (8) $ (26) $ (13) $ (24) Other regulatory assets, deferred (23) (7) (14) (2) — Other regulatory liabilities, current 72 29 19 22 2 Other regulatory liabilities, deferred 31 9 2 20 — Total energy-related derivative gains (losses) $ 9 $ 23 $ (19) $ 27 $ (22)
Schedule of Pre-Tax Effects of Hedging on AOCI	For the three and nine months ended September 30, 2023 and 2022, the pre-tax effects of cash flow and fair value hedge accounting on accumulated OCI for the applicable Registrants were as follows: Gain (Loss) Recognized in OCI on Derivatives For the Three Months Ended September 30, For the Nine Months Ended September 30, 2023 2022 2023 2022 (in millions) (in millions) Southern Company Cash flow hedges: Energy-related derivatives $ (4) $ 11 $ (55) $ 51 Interest rate derivatives (3) 6 (12) 36 Foreign currency derivatives (15) (35) (6) (137) Fair value hedges (*) : Foreign currency derivatives 27 20 28 18 Total $ 5 $ 2 $ (45) $ (32) Georgia Power Cash flow hedges: Interest rate derivatives $ — $ — $ (3) $ 31 Southern Power Cash flow hedges: Energy-related derivatives $ — $ (11) $ (14) $ (4) Foreign currency derivatives (15) (35) (6) (137) Total $ (15) $ (46) $ (20) $ (141) Southern Company Gas Cash flow hedges: Energy-related derivatives $ (4) $ 22 $ (41) $ 55 Interest rate derivatives (4) 5 — — Total $ (8) $ 27 $ (41) $ 55 (*) Represents amounts excluded from the assessment of effectiveness for which the difference between changes in fair value and periodic amortization is recorded in OCI.
Schedule of Pre-Tax Effects of Cash Flow and Fair Value Hedging on Income	For the three and nine months ended September 30, 2023 and 2022, the pre-tax effects of cash flow and fair value hedge accounting on income were as follows: Location and Amount of Gain (Loss) Recognized in Income on Cash Flow and Fair Value Hedging Relationships For the Three Months Ended September 30, For the Nine Months Ended September 30, 2023 2022 2023 2022 (in millions) (in millions) Southern Company Total cost of natural gas $ 102 $ 294 $ 1,199 $ 1,840 Gain (loss) on energy-related cash flow hedges (a) (4) 9 (32) 28 Total other operations and maintenance 1,424 1,527 4,352 4,568 Gain (loss) on energy-related cash flow hedges (a) (1) — (2) — Total depreciation and amortization 1,143 922 3,365 2,728 Gain (loss) on energy-related cash flow hedges (a) (5) (1) (18) 5 Total interest expense, net of amounts capitalized (620) (511) (1,812) (1,461) Gain (loss) on interest rate cash flow hedges (a) (22) (7) (31) (19) Gain (loss) on foreign currency cash flow hedges (a) (3) (3) (8) (16) Gain (loss) on interest rate fair value hedges (b) (47) (102) (50) (300) Total other income (expense), net 141 132 428 414 Gain (loss) on foreign currency cash flow hedges (a)(c) (14) (32) (4) (129) Gain (loss) on foreign currency fair value hedges (7) (59) 19 (180) Amount excluded from effectiveness testing recognized in earnings (27) (21) (28) (17) Southern Power Total depreciation and amortization $ 130 $ 133 $ 380 $ 384 Gain (loss) on energy-related cash flow hedges (a) (5) (1) (18) 5 Total interest expense, net of amounts capitalized (32) (32) (98) (105) Gain (loss) on foreign currency cash flow hedges (a) (3) (3) (8) (16) Total other income (expense), net 4 3 8 5 Gain (loss) on foreign currency cash flow hedges (a)(c) (14) (32) (4) (129) Southern Company Gas Total cost of natural gas $ 102 $ 294 $ 1,199 $ 1,840 Gain (loss) on energy-related cash flow hedges (a) (4) 9 (32) 28 Total other operations and maintenance 264 252 879 824 Gain (loss) on energy-related cash flow hedges (a) (1) — (2) — Total interest expense, net of amounts capitalized (77) (65) (226) (187) Gain (loss) on interest rate cash flow hedges (a) (18) (2) (18) (3) Gain (loss) on interest rate fair value hedges (b) (11) (30) (14) (87) (a) Reclassified from accumulated OCI into earnings. (b) For fair value hedges, changes in the fair value of the derivative contracts are generally equal to changes in the fair value of the underlying debt and have no material impact on income. (c) The reclassification from accumulated OCI into other income (expense), net completely offsets currency gains and losses arising from changes in the U.S. currency exchange rates used to record the euro-denominated notes.
Schedule of Cumulative Basis Adjustments for Fair Value Hedges	At September 30, 2023 and December 31, 2022, the following amounts were recorded on the balance sheets related to cumulative basis adjustments for fair value hedges: Carrying Amount of the Hedged Item Cumulative Amount of Fair Value Hedging Adjustment included in Carrying Amount of the Hedged Item Balance Sheet Location of Hedged Items At September 30, 2023 At December 31, 2022 At September 30, 2023 At December 31, 2022 (in millions) (in millions) Southern Company Long-term debt $ (2,873) $ (2,927) $ 328 $ 282 Southern Company Gas Long-term debt $ (402) $ (415) $ 95 $ 81
Schedule of Pre-tax Effect of Interest Rate and Energy Related Derivatives on Income	For the three and nine months ended September 30, 2023 and 2022, the pre-tax effects of energy-related derivatives not designated as hedging instruments on the statements of income of Southern Company and Southern Company Gas were as follows: Gain (Loss) Three Months Ended September 30, Nine Months Ended September 30, Derivatives in Non-Designated Hedging Relationships Statements of Income Location 2023 2022 2023 2022 (in millions) (in millions) Energy-related derivatives: Natural gas revenues (*) $ — $ 3 $ — $ (10) Cost of natural gas 7 (2) 36 (7) Total derivatives in non-designated hedging relationships $ 7 $ 1 $ 36 $ (17) (*) Excludes $14 million of gains for the nine months ended September 30, 2023, and immaterial amounts for all other periods presented, recorded in natural gas revenues associated with weather derivatives.

Acquisitions and Dispositions (

Acquisitions and Dispositions (Tables)	9 Months Ended
	Sep. 30, 2023
Business Combination and Asset Acquisition [Abstract]
Schedule of Asset Acquisitions	Southern Power's asset acquisitions during the nine months ended September 30, 2023 are detailed in the following table: Project Facility Resource Seller Approximate Nameplate Capacity ( MW ) Location Southern Power Ownership Percentage Expected COD PPA Contract Period Millers Branch (*) Solar EDF Renewables, Inc. 200 Haskell County, TX 100% Fourth quarter 2025 20 years South Cheyenne Solar Hanwha Q Cells USA Corp. 150 Laramie County, WY 100% First quarter 2024 20 years (*) The project includes an option to expand capacity up to an additional 300 MWs.

Segment and Related Informati_2

Segment and Related Information (Tables)	9 Months Ended
	Sep. 30, 2023
Segment Reporting [Abstract]
Schedule of Financial Data for Business Segments	Financial data for business segments and products and services for the three and nine months ended September 30, 2023 and 2022 was as follows: Electric Utilities Traditional Southern Eliminations Total Southern Company Gas All Eliminations Consolidated (in millions) Three Months Ended September 30, 2023 Operating revenues $ 5,674 $ 653 $ (160) $ 6,167 $ 689 $ 154 $ (30) $ 6,980 Segment net income (loss) (a)(b)(c) 1,419 100 — 1,519 82 (179) — 1,422 Nine Months Ended September 30, 2023 Operating revenues $ 14,145 $ 1,686 $ (417) $ 15,414 $ 3,417 $ 499 $ (122) $ 19,208 Segment net income (loss) (a)(b)(c)(d) 2,852 288 — 3,140 475 (490) (4) 3,121 At September 30, 2023 Goodwill $ — $ 2 $ — $ 2 $ 5,015 $ 144 $ — $ 5,161 Total assets 99,464 13,090 (568) 111,986 24,823 2,370 (858) 138,321 Three Months Ended September 30, 2022 Operating revenues $ 6,938 $ 1,180 $ (691) $ 7,427 $ 857 $ 135 $ (41) $ 8,378 Segment net income (loss) (a)(b) 1,445 95 — 1,540 83 (152) 1 1,472 Nine Months Ended September 30, 2022 Operating revenues $ 16,716 $ 2,618 $ (1,391) $ 17,943 $ 3,998 $ 418 $ (127) $ 22,232 Segment net income (loss) (a)(b) 3,256 265 — 3,521 516 (415) (11) 3,611 At December 31, 2022 Goodwill $ — $ 2 $ — $ 2 $ 5,015 $ 144 $ — $ 5,161 Total assets 95,861 13,081 (659) 108,283 24,621 2,665 (678) 134,891 (a) Attributable to Southern Company. (b) For the traditional electric operating companies, includes pre-tax charges (credits) to income at Georgia Power for the estimated probable loss associated with the construction of Plant Vogtle Units 3 and 4 of $160 million ($120 million after tax) for the three and nine months ended September 30, 2023 and $(70) million ($(52) million after tax) and $(18) million ($(13) million after tax) for the three and nine months ended September 30, 2022, respectively. See Note (B) and Note 2 to the financial statements in Item 8 of the Form 10-K under "Georgia Power – Nuclear Construction" for additional information. (c) For Southern Power, includes an $18 million pre-tax loss recovery ($9 million after tax and partnership allocations) for the three and nine months ended September 30, 2023 related to an arbitration interim award and a $16 million pre-tax gain ($12 million after tax) on the sale of spare parts for the nine months ended September 30, 2023. See Note (C) under "General Litigation Matters – Southern Power" for additional information. (d) For Southern Company Gas, includes a pre-tax charge of approximately $38 million ($28 million after tax) associated with the disallowance of certain capital expenditures at Nicor Gas. See Note (B) under "Southern Company Gas" for additional information. Products and Services Electric Utilities' Revenues Retail Wholesale Other Total (in millions) Three Months Ended September 30, 2023 $ 5,139 $ 727 $ 301 $ 6,167 Three Months Ended September 30, 2022 5,961 1,197 269 7,427 Nine Months Ended September 30, 2023 $ 12,597 $ 1,930 $ 887 $ 15,414 Nine Months Ended September 30, 2022 14,363 2,798 782 17,943 Southern Company Gas' Revenues Gas Gas Other Total (in millions) Three Months Ended September 30, 2023 $ 617 $ 56 $ 16 $ 689 Three Months Ended September 30, 2022 748 85 24 857 Nine Months Ended September 30, 2023 $ 2,989 $ 376 $ 52 $ 3,417 Nine Months Ended September 30, 2022 3,513 420 65 3,998 Business segment financial data for the three months ended September 30, 2023 and 2022 was as follows: Gas Distribution Operations Gas Gas Marketing Services Total All Other Eliminations Consolidated (in millions) Three Months Ended September 30, 2023 Operating revenues $ 619 $ 8 $ 56 $ 683 $ 8 $ (2) $ 689 Segment net income (loss) 70 24 2 96 (14) — 82 Nine Months Ended September 30, 2023 Operating revenues $ 3,002 $ 24 $ 376 $ 3,402 $ 30 $ (15) $ 3,417 Segment net income (*) 352 73 59 484 (9) — 475 Total assets at September 30, 2023 22,625 1,542 1,519 25,686 9,795 (10,658) 24,823 Three Months Ended September 30, 2022 Operating revenues $ 751 $ 8 $ 85 $ 844 $ 16 $ (3) $ 857 Segment net income (loss) 59 24 (2) 81 2 — 83 Nine Months Ended September 30, 2022 Operating revenues $ 3,533 $ 24 $ 420 $ 3,977 $ 43 $ (22) $ 3,998 Segment net income 365 76 65 506 10 — 516 Total assets at December 31, 2022 22,040 1,577 1,616 25,233 8,943 (9,555) 24,621 (*) For gas distribution operations, includes a pre-tax charge of approximately $38 million ($28 million after tax) associated with the disallowance of certain capital expenditures at Nicor Gas. See Note (B) under "Southern Company Gas" for additional information.
Schedule of Financial Data for Products and Services	Electric Utilities' Revenues Retail Wholesale Other Total (in millions) Three Months Ended September 30, 2023 $ 5,139 $ 727 $ 301 $ 6,167 Three Months Ended September 30, 2022 5,961 1,197 269 7,427 Nine Months Ended September 30, 2023 $ 12,597 $ 1,930 $ 887 $ 15,414 Nine Months Ended September 30, 2022 14,363 2,798 782 17,943 Southern Company Gas' Revenues Gas Gas Other Total (in millions) Three Months Ended September 30, 2023 $ 617 $ 56 $ 16 $ 689 Three Months Ended September 30, 2022 748 85 24 857 Nine Months Ended September 30, 2023 $ 2,989 $ 376 $ 52 $ 3,417 Nine Months Ended September 30, 2022 3,513 420 65 3,998

Introduction - Schedule of Good

Introduction - Schedule of Goodwill (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Goodwill [Line Items]
Goodwill	$ 5,161	$ 5,161
SOUTHERN Co GAS
Goodwill [Line Items]
Goodwill	5,015	5,015
SOUTHERN Co GAS | Gas distribution operations
Goodwill [Line Items]
Goodwill	4,034	4,034
SOUTHERN Co GAS | Gas marketing services
Goodwill [Line Items]
Goodwill	$ 981	$ 981

Introduction - Schedule of Othe

Introduction - Schedule of Other Intangible Assets (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Subject to amortization:
Gross Carrying Amount	$ 669	$ 671
Accumulated Amortization	(367)	(340)
Other Intangible Assets, Net	302	331
Not subject to amortization:
FCC licenses	75	75
Total other intangible assets
Gross Carrying Amount	744	746
Accumulated Amortization	(367)	(340)
Other Intangible Assets, Net	377	406
Customer relationships
Subject to amortization:
Gross Carrying Amount	211	212
Accumulated Amortization	(169)	(162)
Other Intangible Assets, Net	42	50
Total other intangible assets
Accumulated Amortization	(169)	(162)
Trade names
Subject to amortization:
Gross Carrying Amount	63	64
Accumulated Amortization	(50)	(44)
Other Intangible Assets, Net	13	20
Total other intangible assets
Accumulated Amortization	(50)	(44)
PPA fair value adjustments
Subject to amortization:
Gross Carrying Amount	390	390
Accumulated Amortization	(143)	(129)
Other Intangible Assets, Net	247	261
Total other intangible assets
Accumulated Amortization	(143)	(129)
Other
Subject to amortization:
Gross Carrying Amount	5	5
Accumulated Amortization	(5)	(5)
Other Intangible Assets, Net	0	0
Total other intangible assets
Accumulated Amortization	(5)	(5)
SOUTHERN POWER CO
Subject to amortization:
Accumulated Amortization	(143)	(129)
Total other intangible assets
Accumulated Amortization	(143)	(129)
SOUTHERN POWER CO | PPA fair value adjustments
Subject to amortization:
Gross Carrying Amount	390	390
Accumulated Amortization	(143)	(129)
Other Intangible Assets, Net	247	261
Total other intangible assets
Accumulated Amortization	(143)	(129)
SOUTHERN Co GAS
Subject to amortization:
Gross Carrying Amount	182	182
Accumulated Amortization	(163)	(156)
Other Intangible Assets, Net	19	26
Total other intangible assets
Accumulated Amortization	(163)	(156)
Other Intangible Assets, Net	19	26
SOUTHERN Co GAS | Customer relationships
Subject to amortization:
Gross Carrying Amount	156	156
Accumulated Amortization	(143)	(139)
Other Intangible Assets, Net	13	17
Total other intangible assets
Accumulated Amortization	(143)	(139)
SOUTHERN Co GAS | Trade names
Subject to amortization:
Gross Carrying Amount	26	26
Accumulated Amortization	(20)	(17)
Other Intangible Assets, Net	6	9
Total other intangible assets
Accumulated Amortization	$ (20)	$ (17)

Introduction - Schedule of Amor

Introduction - Schedule of Amortization of Other Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 10	$ 11	$ 27	$ 30
Decrease in operating revenues	5	14	5	15
SOUTHERN POWER CO
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	5	5	14	15
SOUTHERN Co GAS
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 3	$ 4	$ 7	$ 9

Introduction - Schedule of Cash

Introduction - Schedule of Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	$ 1,676	$ 1,917
Restricted cash:
Total cash, cash equivalents, and restricted cash	1,890	2,037	$ 2,013	$ 1,829
Other current assets
Restricted cash:
Restricted cash	176	62
Other deferred charges and assets
Restricted cash:
Restricted cash	38	58
ALABAMA POWER CO
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	621	687
Restricted cash:
Total cash, cash equivalents, and restricted cash	729	687	1,458	1,060
ALABAMA POWER CO | Other current assets
Restricted cash:
Restricted cash	108	0
ALABAMA POWER CO | Other deferred charges and assets
Restricted cash:
Restricted cash	0	0
GEORGIA POWER CO
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	173	364
Restricted cash:
Total cash, cash equivalents, and restricted cash	256	480	33	33
GEORGIA POWER CO | Other current assets
Restricted cash:
Restricted cash	48	60
GEORGIA POWER CO | Other deferred charges and assets
Restricted cash:
Restricted cash	35	56
SOUTHERN POWER CO
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	236	131
Restricted cash:
Total cash, cash equivalents, and restricted cash	257	133	231	135
SOUTHERN POWER CO | Other current assets
Restricted cash:
Restricted cash	18	0
SOUTHERN POWER CO | Other deferred charges and assets
Restricted cash:
Restricted cash	3	3
SOUTHERN POWER CO | Proceeds From Issuance Of Solid Waste Disposal Facility Revenue Bonds
Restricted cash:
Restricted cash	18
SOUTHERN POWER CO | Estimated Construction Completion Costs | Deuel Harvest
Restricted cash:
Restricted cash	3	3
SOUTHERN Co GAS
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	397	81
Restricted cash:
Total cash, cash equivalents, and restricted cash	399	83	$ 28	$ 48
SOUTHERN Co GAS | Other current assets
Restricted cash:
Restricted cash	2	2
SOUTHERN Co GAS | Other deferred charges and assets
Restricted cash:
Restricted cash	$ 0	$ 0

Introduction - Storm Damage Res

Introduction - Storm Damage Reserves (Details) - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Aug. 31, 2023	Sep. 30, 2023
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance at December 31, 2022		$ 216
Balance at September 30, 2023		16
Accrued Storm Reserve
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Accrual		42
Storm Reserve
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Weather-related damages		(242)
ALABAMA POWER CO
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance at December 31, 2022		97
Balance at September 30, 2023		71
ALABAMA POWER CO | Accrued Storm Reserve
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Accrual		9
ALABAMA POWER CO | Storm Reserve
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Weather-related damages		(35)
GEORGIA POWER CO
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance at December 31, 2022		83
Balance at September 30, 2023		97
GEORGIA POWER CO | Accrued Storm Reserve
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Accrual	$ 110	24
GEORGIA POWER CO | Storm Reserve
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Weather-related damages		(204)
MISSISSIPPI POWER CO
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance at December 31, 2022		36
Balance at September 30, 2023		42
MISSISSIPPI POWER CO | Accrued Storm Reserve
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Accrual		9
MISSISSIPPI POWER CO | Storm Reserve
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Weather-related damages		$ (3)

Introduction - Asset Retirement

Introduction - Asset Retirement Obligations (Details) - USD ($) $ in Millions	1 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 06, 2023
GEORGIA POWER CO
Schedule of Asset Retirement Obligation [Line Items]
Asset retirement obligation, period increase (decrease)	$ 175
ALABAMA POWER CO
Schedule of Asset Retirement Obligation [Line Items]
Asset retirement obligation, period increase (decrease)		$ 15
Plant Vogtle Unit 3
Schedule of Asset Retirement Obligation [Line Items]
Asset retirement obligations			$ 90

Introduction - Decommissioning

Introduction - Decommissioning Expenses (Details) $ in Millions	1 Months Ended	9 Months Ended
	Jun. 30, 2023	Sep. 30, 2023 USD ($)
Estimated Inflation Rate
Liability for Claims and Claims Adjustment Expense [Line Items]
ARO measurement input	0.045
Estimated Trust Earnings
Liability for Claims and Claims Adjustment Expense [Line Items]
ARO measurement input	0.070
ALABAMA POWER CO
Liability for Claims and Claims Adjustment Expense [Line Items]
Total site study costs		$ 2,048
ALABAMA POWER CO | Plant Farley
Liability for Claims and Claims Adjustment Expense [Line Items]
Decommissioning costs (term)		5 years
Radiated structures | ALABAMA POWER CO
Liability for Claims and Claims Adjustment Expense [Line Items]
Total site study costs		$ 1,402
Spent fuel management | ALABAMA POWER CO
Liability for Claims and Claims Adjustment Expense [Line Items]
Total site study costs		513
Non-radiated structures | ALABAMA POWER CO
Liability for Claims and Claims Adjustment Expense [Line Items]
Total site study costs		$ 133

Regulatory Matters - Schedule o

Regulatory Matters - Schedule of Cost Recovery Clauses (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
ALABAMA POWER CO | Other regulatory assets, current
Loss Contingencies [Line Items]
Rate CNP Compliance	$ 0	$ 47
Rate CNP PPA	17	18
Retail Energy Cost Recovery	208	102
ALABAMA POWER CO | Other regulatory assets, deferred
Loss Contingencies [Line Items]
Rate CNP PPA	90	102
Retail Energy Cost Recovery	80	520
ALABAMA POWER CO | Other Regulatory Liabilities, Deferred
Loss Contingencies [Line Items]
Rate CNP Compliance	3	0
GEORGIA POWER CO | Receivables – under recovered fuel clause revenues
Loss Contingencies [Line Items]
Fuel Cost Recovery(*)	730	0
GEORGIA POWER CO | Deferred under recovered fuel clause revenues
Loss Contingencies [Line Items]
Fuel Cost Recovery(*)	1,279	2,056
MISSISSIPPI POWER CO | Other regulatory assets, current
Loss Contingencies [Line Items]
Ad Valorem Tax	3	12
MISSISSIPPI POWER CO | Other regulatory assets, deferred
Loss Contingencies [Line Items]
Ad Valorem Tax	11	19
MISSISSIPPI POWER CO | Receivables – customer accounts, net
Loss Contingencies [Line Items]
Fuel Cost Recovery(*)	25	1
SOUTHERN Co GAS
Loss Contingencies [Line Items]
Natural gas cost under recovery	0	108
SOUTHERN Co GAS | Other regulatory assets, current
Loss Contingencies [Line Items]
Natural gas cost under recovery	0	108
SOUTHERN Co GAS | Natural gas cost over recovery
Loss Contingencies [Line Items]
Natural gas cost under recovery	$ 165	$ 0

Regulatory Matters - APC Certif

Regulatory Matters - APC Certificate of Convenience and Necessity (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2020
Public Utilities, General Disclosures [Line Items]
Construction work in progress	$ 8,496	$ 10,896
Plant in service, net of depreciation	88,374	82,232
ALABAMA POWER CO
Public Utilities, General Disclosures [Line Items]
Construction work in progress	1,759	1,526
Plant in service, net of depreciation	23,271	$ 23,002
ALABAMA POWER CO | Plant Barry Unit 8
Public Utilities, General Disclosures [Line Items]
Estimated in-service cost			$ 652
Construction work in progress	583
Construction in progress, work in progress amount	578
Plant in service, net of depreciation	$ 5

Regulatory Matters - APC Excess

Regulatory Matters - APC Excess Accumulated Deferred Income Tax Accounting Order (Details) $ in Millions	Oct. 03, 2023 USD ($)
ALABAMA POWER CO | Subsequent Event
Public Utilities, General Disclosures [Line Items]
Deferred income taxes	$ 24

Regulatory Matters - APC Rate C

Regulatory Matters - APC Rate CNP New Plant (Details) $ in Millions	Mar. 24, 2023 USD ($)
ALABAMA POWER CO
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease) amount	$ 78

Regulatory Matters - APC Renewa

Regulatory Matters - APC Renewable Generation Certificate (Details)	Jun. 14, 2023 MW	Jun. 13, 2023 MW	Apr. 04, 2023 claim MW
Public Utilities, General Disclosures [Line Items]
Renewable generation certificate, number of new solar power purchase agreements (in claims) | claim			2
ALABAMA POWER CO
Public Utilities, General Disclosures [Line Items]
Renewable generation certificate, additional generating capacity procured (in MWs)			160
Renewable generation certificate, generating capacity (in MWs)			490
Renewable generation certificate, authorized generating capacity (in MWs)			500
Renewable generation certificate, additional renewable capacity (in MWs)	2,400
Renewable generation certificate, size of allowable projects (in MWs)	200	80
Renewable generation certificate, annual approval limit (in MWs)	400	160

Regulatory Matters - APC Reliab

Regulatory Matters - APC Reliability Reserve Accounting Matter (Details) - USD ($) $ in Millions	Sep. 30, 2023	Aug. 18, 2023	Dec. 31, 2022
Public Utilities, General Disclosures [Line Items]
Reliability reserve balance	$ 16		$ 216
ALABAMA POWER CO
Public Utilities, General Disclosures [Line Items]
Reliability reserve balance	$ 71		$ 97
Reliability Reserve | ALABAMA POWER CO
Public Utilities, General Disclosures [Line Items]
Reliability reserve balance		$ 166

Regulatory Matters - GPC Rate M

Regulatory Matters - GPC Rate Matters (Details) - GEORGIA POWER CO - Subsequent Event $ in Millions	Oct. 02, 2023 USD ($)
Traditional Base
Public Utilities, General Disclosures [Line Items]
Increase (decrease) in tariff	$ 275
Environmental Compliance Cost Recovery, Traditional
Public Utilities, General Disclosures [Line Items]
Increase (decrease) in tariff	(99)
Demand Side-Management
Public Utilities, General Disclosures [Line Items]
Increase (decrease) in tariff	10
Municipal Franchise Fee
Public Utilities, General Disclosures [Line Items]
Increase (decrease) in tariff	$ 5

Regulatory Matters - GPC Plant

Regulatory Matters - GPC Plant Vogtle Unit 3 and Common Facilities Rate Proceeding (Details) - GEORGIA POWER CO - USD ($) $ in Millions				1 Months Ended	9 Months Ended	12 Months Ended
	Aug. 30, 2023	Aug. 01, 2023	May 16, 2023	Nov. 30, 2021	Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2009	Aug. 31, 2018
Loss Contingencies [Line Items]
Requested rate increase (decrease) amount			$ 1,100
Requested revenues increase (decrease) percentage			54%
Plant Vogtle Units 3 And 4
Loss Contingencies [Line Items]
Recovery of construction and capital costs	$ 7,562
Requested recovery of associated retail base items	1,020
Estimated in-service capital cost							$ 4,418
Approved rate increase (decrease)	5,462			$ 2,100
Approved recovery of retail rate items				$ 362
Associated retail rate base items	656
Return on equity reduction, negative impact on earnings					$ 12	$ 300
Requested rate increase (decrease) amount	$ 729
Requested revenues increase (decrease) percentage	5%
Percentage of ownership interest required for voting for continuing construction								90%
Percentage of costs, disallowed for recovery					6%
Plant Vogtle Unit 3
Loss Contingencies [Line Items]
Requested rate increase, annual amount		$ 318
Seventeenth Vogtle Construction Monitoring Report | Plant Vogtle Units 3 And 4
Loss Contingencies [Line Items]
Recovery of construction and capital costs	$ 8,826
Requested recovery of associated retail base items	$ 1,070
Twenty Fourth Vogtle Construction Monitoring Report | Plant Vogtle Units 3 And 4
Loss Contingencies [Line Items]
Cost settlement agreement revised forecast, net of payments					$ 7,300

Regulatory Matters - GPC Fuel C

Regulatory Matters - GPC Fuel Cost Recovery (Details) $ in Millions	May 16, 2023 USD ($)
Public Utilities, General Disclosures [Line Items]
Under recovered fuel balance to be recovered	$ 2,200
GEORGIA POWER CO
Public Utilities, General Disclosures [Line Items]
Requested revenues increase (decrease) percentage	54%
Requested rate increase (decrease) amount	$ 1,100
Under recovered fuel balance to be recovered, period of recovery	3 years
GEORGIA POWER CO | Maximum
Public Utilities, General Disclosures [Line Items]
Approved rate increase, percentage	40%
Approved rate increase (decrease)	$ 200

Regulatory Matters - GPC Integr

Regulatory Matters - GPC Integrated Resource Plan (Details) - GEORGIA POWER CO $ in Millions		1 Months Ended	60 Months Ended	61 Months Ended
	Oct. 27, 2023 turbine MW	Aug. 31, 2022 USD ($)	Dec. 31, 2028 MW	Dec. 31, 2028 MW
Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Requested additional generating capacity (in MWs)			750
Subsequent Event
Public Utilities, General Disclosures [Line Items]
Number of turbines | turbine	3
Subsequent Event | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Requested additional generating capacity (in MWs)				230
Subsequent Event | Maximum
Public Utilities, General Disclosures [Line Items]
Requested additional generating capacity (in MWs)	1,000
Plant Tugalo
Public Utilities, General Disclosures [Line Items]
Planned expenses to modernize plant | $		$ 115
Plant Yates | Subsequent Event | Maximum
Public Utilities, General Disclosures [Line Items]
Requested additional generating capacity (in MWs)	1,400

Regulatory Matters - GPC Storm

Regulatory Matters - GPC Storm Damage Recovery (Details) - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Aug. 31, 2023	Sep. 30, 2023
Accrued Storm Reserve
Public Utilities, General Disclosures [Line Items]
Accrual		$ 42
GEORGIA POWER CO
Public Utilities, General Disclosures [Line Items]
Weather-related damages		31
Regulatory balance		97
GEORGIA POWER CO | Accrued Storm Reserve
Public Utilities, General Disclosures [Line Items]
Accrual	$ 110	24
ALABAMA POWER CO | Accrued Storm Reserve
Public Utilities, General Disclosures [Line Items]
Accrual		$ 9

Regulatory Matters - GPC Nuclea

Regulatory Matters - GPC Nuclear Construction (Details) - GEORGIA POWER CO $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2023 USD ($)	Dec. 31, 2012 utility MW	Oct. 06, 2023 pump	Sep. 20, 2023 USD ($)	Aug. 31, 2018
Plant Vogtle Units 3 And 4
Loss Contingencies [Line Items]
Proportionate ownership share	45.70%
Number of construction units approved | utility		2
Electric generating capacity in mega watts under consortium agreement | MW		1,100
Estimated cost to complete, construction contingency estimate, financing costs	$ 3,500
Estimated cost to complete, construction contingency estimate, financing costs, incurred to date	3,400
Construction contingency estimate				$ 43
Monthly AFUDC	$ 25
Percentage of ownership interest required for voting for continuing construction					90%
Plant Vogtle Units 3 And 4 | Vogtle Owners
Loss Contingencies [Line Items]
Period of notice required in the event letters of credit are not renewed	30 days
Plant Vogtle Unit 4 | Subsequent Event
Loss Contingencies [Line Items]
Number of RPCs | pump			1
Minimum | Plant Vogtle Units 3 And 4 | COVID-19
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss, loss of productivity, term	3 months
Maximum | Plant Vogtle Units 3 And 4 | Subsequent Event
Loss Contingencies [Line Items]
Number of RPCs | pump			7
Maximum | Plant Vogtle Units 3 And 4 | COVID-19
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss, loss of productivity, term	4 months
Estimate of possible loss	$ 200
Maximum | Plant Vogtle Unit 4 | Subsequent Event
Loss Contingencies [Line Items]
Number of RPCs | pump			4

Regulatory Matters - GPC Nucl_2

Regulatory Matters - GPC Nuclear Construction Cost and Schedule (Details) - GEORGIA POWER CO - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12003 Months Ended
	Sep. 30, 2023	Sep. 30, 2023	Dec. 31, 2022
Loss Contingencies [Line Items]
Pre-tax charge to income	$ 160		$ 407
Plant Vogtle Units 3 And 4
Loss Contingencies [Line Items]
Base project capital cost forecast	10,736	$ 10,736
Construction contingency estimate	17	17
Total project capital cost forecast	10,753	10,753
Net investment as of end of the period	(10,495)	(10,495)
Remaining estimate to complete	258	258
Estimated cost to complete, costs not shared with other owners	610	610
Estimated cost to complete, construction monitoring costs approved for recovery	33	33
Pre-tax charge to income			$ 567
Expected capitalized costs		420
Capitalized interest accrued	385	385
Plant Vogtle Units 3 And 4 | Twenty Fifth Vogtle Construction Monitoring Report
Loss Contingencies [Line Items]
Guarantor obligations	$ 1,700	1,700
Customer refund		$ 188

Regulatory Matters - GPC Amendm

Regulatory Matters - GPC Amendments to the Vogtle Joint Ownership Agreements (Details) - USD ($) $ in Millions				1 Months Ended	3 Months Ended	9 Months Ended	12003 Months Ended
	Oct. 17, 2023	Oct. 05, 2023	Jan. 11, 2018	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2023	Dec. 31, 2022	Jul. 31, 2022	Jun. 30, 2022	Aug. 31, 2018
Public Utilities, General Disclosures [Line Items]
Agreement with third party, amount of costs over projected forecast to be paid by company				20%
GEORGIA POWER CO
Public Utilities, General Disclosures [Line Items]
Pre-tax charge to income					$ 160		$ 407
After tax charge to income					120		304
Plant Vogtle Units 3 And 4 | GEORGIA POWER CO
Public Utilities, General Disclosures [Line Items]
Production tax credits, aggregate purchase price, maximum						$ 300
Preliminary estimated cost to complete					$ 10,753	$ 10,753
Additional construction capital costs			$ 3,300
Remaining share of construction costs, agreement to pay, percentage						100%
Percentage of ownership interest required for voting for continuing construction										90%
Percentage of costs, disallowed for recovery						6%
Costs disallowed for recovery, period						6 months
Public utilities, extension project schedule, term						1 year
Estimated cost to complete, starting dollar amount								$ 18,380
Pre-tax charge to income							$ 567
Proportionate ownership share					45.70%	45.70%
Plant Vogtle Units 3 And 4 | GEORGIA POWER CO | Subsequent Event
Public Utilities, General Disclosures [Line Items]
Additional construction capital costs	$ 17	$ 308
Remaining share of construction costs, agreement to pay, percentage		66%
Plant Vogtle Units 3 And 4 | GEORGIA POWER CO | Vogtle Owners | Tender Provision Dispute
Public Utilities, General Disclosures [Line Items]
Estimated cost to complete, starting dollar amount									$ 17,100
Plant Vogtle Units 3 And 4 | GEORGIA POWER CO | MEAG Power
Public Utilities, General Disclosures [Line Items]
Payment of power costs				$ 92
Plant Vogtle Units 3 And 4 | GEORGIA POWER CO | Oglethorpe Power Corporation | Subsequent Event
Public Utilities, General Disclosures [Line Items]
Payment of power costs		$ 105
Plant Vogtle Units 3 And 4 | GEORGIA POWER CO | Dalton Utilities | Subsequent Event
Public Utilities, General Disclosures [Line Items]
Payment of power costs	$ 6
Plant Vogtle Units 3 And 4 | GEORGIA POWER CO | Category I
Public Utilities, General Disclosures [Line Items]
Preliminary estimated cost to complete					$ 8,400	$ 8,400
Additional construction capital costs, threshold						$ 800
Plant Vogtle Units 3 And 4 | GEORGIA POWER CO | Category II
Public Utilities, General Disclosures [Line Items]
Percentage of construction costs, responsibility to pay						55.70%
Additional construction capital costs						$ 80
Plant Vogtle Units 3 And 4 | GEORGIA POWER CO | Category II | Vogtle Owners
Public Utilities, General Disclosures [Line Items]
Percentage of construction costs, responsibility to pay						44.30%
Plant Vogtle Units 3 And 4 | GEORGIA POWER CO | Category II | Minimum
Public Utilities, General Disclosures [Line Items]
Additional construction capital costs, threshold						$ 800
Plant Vogtle Units 3 And 4 | GEORGIA POWER CO | Category II | Maximum
Public Utilities, General Disclosures [Line Items]
Additional construction capital costs, threshold						$ 1,600
Plant Vogtle Units 3 And 4 | GEORGIA POWER CO | Category III
Public Utilities, General Disclosures [Line Items]
Percentage of construction costs, responsibility to pay						65.70%
Additional construction capital costs						$ 100
Plant Vogtle Units 3 And 4 | GEORGIA POWER CO | Category III | Vogtle Owners
Public Utilities, General Disclosures [Line Items]
Percentage of construction costs, responsibility to pay						34.30%
Plant Vogtle Units 3 And 4 | GEORGIA POWER CO | Category III | Minimum
Public Utilities, General Disclosures [Line Items]
Additional construction capital costs, threshold						$ 1,600
Plant Vogtle Units 3 And 4 | GEORGIA POWER CO | Category III | Maximum
Public Utilities, General Disclosures [Line Items]
Additional construction capital costs, threshold						$ 2,100

Regulatory Matters - GPC Nucl_3

Regulatory Matters - GPC Nuclear Construction Regulatory Matters (Details) - Plant Vogtle Units 3 And 4 - GEORGIA POWER CO $ in Millions

6 Months Ended

9 Months Ended

12 Months Ended

Jan. 01, 2023 USD ($)

Jan. 01, 2021

Jan. 01, 2020

Jan. 11, 2018 USD ($)

Jan. 01, 2018

Jan. 01, 2016

Jun. 30, 2023 USD ($)

Jun. 30, 2022 USD ($) claim

Sep. 30, 2023 USD ($)

Dec. 31, 2024 USD ($)

Dec. 31, 2023 USD ($)

Dec. 31, 2022 USD ($)

Dec. 31, 2009 USD ($)

Jun. 30, 2021 report

Jun. 30, 2018 USD ($)

Dec. 31, 2013

Public Utilities, General Disclosures [Line Items]

Estimated in-service capital cost

$ 4,418

Financing costs collected, net of tax

$ 3,000

Increase (decrease) in tariff

$ 36

Additional construction capital costs

$ 3,300

Payments for contractor settlement agreement

300

Amendment to estimated in-service capital cost

$ 5,680

Retail rate of return on common equity

10.95%

Public utilities, approved return on equity percentage

5.30%

8.30%

10%

10%

Public utilities, approved return on equity, monthly percentage increase (decrease)

(0.10%)

Return on equity reduction, negative impact on earnings

$ 12

$ 300

Increase to base capital cost forecast not seeking recovery

$ 700

Twenty Fourth Vogtle Construction Monitoring Report

Public Utilities, General Disclosures [Line Items]

Cost settlement agreement revised forecast, net of payments

7,300

Twenty Fifth Vogtle Construction Monitoring Report

Public Utilities, General Disclosures [Line Items]

Number of approved construction management reports | report

25

Requested capital construction costs

7,900

Guarantor obligations

1,700

Customer refund

$ 188

Twenty Sixth Vogtle Construction Monitoring Report

Public Utilities, General Disclosures [Line Items]

Requested capital construction costs

$ 1,600

Number of additional reports reviewed | claim

3

Twenty Ninth Vogtle Construction Monitoring Report

Public Utilities, General Disclosures [Line Items]

Cost settlement agreement revised forecast, net of payments

$ 10,600

Requested capital construction costs

$ 390

Scenario, Forecast

Public Utilities, General Disclosures [Line Items]

Return on equity reduction, negative impact on earnings

$ 60

$ 290

Regulatory Matters - MPC (Detai

Regulatory Matters - MPC (Details) $ in Millions					1 Months Ended
	Jul. 31, 2023 USD ($)	May 02, 2023 USD ($)	Apr. 04, 2023 USD ($)	Apr. 03, 2023 USD ($)	Oct. 31, 2023 MW	Jul. 31, 2022 USD ($)
Loss Contingencies [Line Items]
Minimum annual accrual, amount				$ 8
MISSISSIPPI POWER CO
Loss Contingencies [Line Items]
Approved rate increase (decrease)			$ 12
MISSISSIPPI POWER CO | Subsequent Event
Loss Contingencies [Line Items]
Approved capacity increase (in MWs) | MW					750
MISSISSIPPI POWER CO | Ad Valorem Tax Adjustment
Loss Contingencies [Line Items]
Requested rate increase (decrease) amount		$ (7)
MISSISSIPPI POWER CO | ECO Plan
Loss Contingencies [Line Items]
Approved rate increase (decrease)			$ 3
MISSISSIPPI POWER CO | Municipal And Rural Associations Tariff
Loss Contingencies [Line Items]
Requested rate increase (decrease) amount	$ 16					$ 23
Customer refund payments	$ 6

Regulatory Matters - GAS Schedu

Regulatory Matters - GAS Schedule of Infrastructure Replacement Programs and Capital Projects (Details) - SOUTHERN Co GAS $ in Millions	9 Months Ended
	Sep. 30, 2023 USD ($)
Public Utilities, General Disclosures [Line Items]
Capital expenditures	$ 467
Investing in Illinois
Public Utilities, General Disclosures [Line Items]
Capital expenditures	320
SAVE
Public Utilities, General Disclosures [Line Items]
Capital expenditures	56
System Reinforcement Rider
Public Utilities, General Disclosures [Line Items]
Capital expenditures	84
Pipeline Replacement Program
Public Utilities, General Disclosures [Line Items]
Capital expenditures	$ 7

Regulatory Matters - GAS Nicor

Regulatory Matters - GAS Nicor Gas (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2019
Public Utilities, General Disclosures [Line Items]
Total operating revenues	$ (6,980)		$ (8,378)	$ (19,208)	$ (22,232)
Total operating expenses	4,870		$ 6,185	$ 14,589	$ 17,000
Nicor Gas
Public Utilities, General Disclosures [Line Items]
Pre-tax charge to income	38
After-tax charge to income	$ 28
Nicor Gas | Investing in Illinois
Public Utilities, General Disclosures [Line Items]
Capital expenditures disallowed						$ 32
Capital expenditures						$ 415
Total operating revenues		$ 8
Total operating expenses		$ 30

Regulatory Matters - GAS Atlant

Regulatory Matters - GAS Atlanta Gas Light (Details) $ in Millions	Jul. 14, 2023 USD ($)
SOUTHERN Co GAS
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease) amount	$ 53

Regulatory Matters - GAS Virgin

Regulatory Matters - GAS Virginia Natural Gas (Details) - Virginia Natural Gas - USD ($) $ in Millions	Jun. 07, 2023	Jan. 01, 2023
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease)	$ 48
Public utilities, approved return on equity percentage	9.70%
Public utilities, approved equity capital structure percentage	49.06%
Requested rate increase (decrease) amount		$ 69

Contingencies - General Litigat

Contingencies - General Litigation Matters (Details) $ in Millions	1 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended	16 Months Ended
	Jul. 31, 2023 USD ($)	Mar. 31, 2019 plaintiff	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Dec. 31, 2018 USD ($) defendant plaintiff	Jan. 31, 2023 claim	Jul. 31, 2021 project
Loss Contingencies [Line Items]
Amount awarded					$ 18
Increase in other revenues			$ 6,980	$ 8,378	19,208	$ 22,232
Allocation to NCI			10	12	(68)	(55)
Other revenues
Loss Contingencies [Line Items]
Increase in other revenues			222	178	662	519
GEORGIA POWER CO
Loss Contingencies [Line Items]
Increase in other revenues			3,237	3,889	7,805	9,218
GEORGIA POWER CO | Other revenues
Loss Contingencies [Line Items]
Increase in other revenues			172	130	516	403
GEORGIA POWER CO | Pending Litigation | Class Action Lawsuit
Loss Contingencies [Line Items]
Complaints filed | claim								8
MISSISSIPPI POWER CO
Loss Contingencies [Line Items]
Increase in other revenues			436	510	1,137	1,279
MISSISSIPPI POWER CO | Other revenues
Loss Contingencies [Line Items]
Increase in other revenues			10	13	31	34
MISSISSIPPI POWER CO | Pending Litigation | Purported Violations of Mississippi Consumer Protection Act
Loss Contingencies [Line Items]
Number of plaintiffs | plaintiff							10
Number of defendants | defendant							3
Number of additional plaintiffs | plaintiff		4
Underpayment of refunds							$ 23.5
SOUTHERN POWER CO
Loss Contingencies [Line Items]
Amount awarded			18
Increase in other revenues			653	1,180	1,686	2,618
Allocation to NCI			10	12	(68)	(55)
SOUTHERN POWER CO | Other revenues
Loss Contingencies [Line Items]
Increase in other revenues			18	$ 9	$ 46	$ 27
SOUTHERN POWER CO | Settled Litigation | Southern Power vs First Solar
Loss Contingencies [Line Items]
Number of solar projects | project									5
Proceeds from legal settlements	$ 36
Amount awarded	$ 18		18
Reduction to other operations and maintenance expense			11
Allocation to NCI			6
SOUTHERN POWER CO | Settled Litigation | Southern Power vs First Solar | Other revenues
Loss Contingencies [Line Items]
Increase in other revenues			$ 7

Contingencies - Environmental R

Contingencies - Environmental Remediation (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
GEORGIA POWER CO
Loss Contingencies [Line Items]
Environmental remediation liability, current and former sites	$ 14	$ 15
SOUTHERN Co GAS
Loss Contingencies [Line Items]
Environmental remediation liability, current and former sites	$ 234	$ 256

Contingencies - Other Matters (

Contingencies - Other Matters (Details) - USD ($) $ in Millions			1 Months Ended		9 Months Ended
	Oct. 05, 2023	Oct. 03, 2023	Aug. 31, 2022	Apr. 30, 2019	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2019	Dec. 31, 2022	Dec. 31, 2017	Dec. 31, 2011
Loss Contingencies [Line Items]
Associated penalties and interest previously paid					$ (67)	$ (119)
Penalties and interest final payment					(1,031)	805
Regulatory asset					16			$ 216
ALABAMA POWER CO
Loss Contingencies [Line Items]
Associated penalties and interest previously paid					(21)	(98)
Penalties and interest final payment					(358)	(22)
Regulatory asset					71			97
ALABAMA POWER CO | AT&T
Loss Contingencies [Line Items]
Potential refund amount owed				$ 87
Refund payment period				6 years
MISSISSIPPI POWER CO
Loss Contingencies [Line Items]
Total amount due including penalties and interest			$ 28
Associated penalties and interest previously paid			$ 7		12	36
Penalties and interest final payment					(83)	$ 41
Regulatory asset					$ 42			36
MISSISSIPPI POWER CO | Kemper IGCC
Loss Contingencies [Line Items]
DOE awards									$ 137	$ 270
Government grants received							$ 387
MISSISSIPPI POWER CO | Taxes and Interest
Loss Contingencies [Line Items]
Regulatory asset								$ 3
MISSISSIPPI POWER CO | Subsequent Event
Loss Contingencies [Line Items]
Assessment including penalties and interest		$ 11
Penalties and interest final payment	$ 4

Revenue from Contracts with C_3

Revenue from Contracts with Customers and Lease Income - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 7,107	$ 7,116	$ 18,886	$ 19,599
Total operating revenues	6,980	8,378	19,208	22,232
Retail electric revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	5,139	5,961	12,597	14,363
Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	5,534	4,951	13,035	12,477
Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,543	2,104	5,717	5,282
Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,845	1,637	4,464	4,202
Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,116	1,183	2,770	2,914
Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	30	27	84	79
Natural Gas
Disaggregation of Revenue [Line Items]
Total operating revenues	689	857	3,417	3,998
Natural gas distribution revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	612	744	2,952	3,490
Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	217	331	1,443	1,821
Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	56	93	370	493
Transportation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	275	259	878	872
Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	4	12	33	60
Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	60	49	228	244
Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	727	1,197	1,930	2,798
Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	569	1,045	1,542	2,364
PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	317	812	853	1,739
PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	151	175	490	443
Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	101	58	199	182
Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	62	99	386	458
Gas marketing services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	54	84	358	417
Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	8	15	28	41
Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	(127)	1,262	322	2,633
Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	330	277	971	810
ALABAMA POWER CO
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,230	2,128	5,638	5,315
Total operating revenues	2,083	2,444	5,420	6,023
ALABAMA POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	1,860	2,008	4,708	5,015
ALABAMA POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,069	1,753	5,104	4,487
ALABAMA POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	969	799	2,277	2,049
ALABAMA POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	599	499	1,493	1,285
ALABAMA POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	498	452	1,324	1,143
ALABAMA POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3	3	10	10
ALABAMA POWER CO | Natural gas distribution revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
ALABAMA POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
ALABAMA POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
ALABAMA POWER CO | Transportation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
ALABAMA POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
ALABAMA POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
ALABAMA POWER CO | Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	107	310	375	655
ALABAMA POWER CO | PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	66	187	196	354
ALABAMA POWER CO | PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	26	56	130	135
ALABAMA POWER CO | Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	15	67	49	166
ALABAMA POWER CO | Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
ALABAMA POWER CO | Gas marketing services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
ALABAMA POWER CO | Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
ALABAMA POWER CO | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	(147)	316	(218)	708
ALABAMA POWER CO | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	54	65	159	173
GEORGIA POWER CO
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,388	3,093	7,754	7,767
Total operating revenues	3,237	3,889	7,805	9,218
GEORGIA POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	2,996	3,703	7,142	8,629
GEORGIA POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,177	2,927	7,198	7,274
GEORGIA POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,473	1,212	3,202	2,995
GEORGIA POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,151	1,051	2,733	2,688
GEORGIA POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	528	642	1,195	1,529
GEORGIA POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	25	22	68	62
GEORGIA POWER CO | Natural gas distribution revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
GEORGIA POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
GEORGIA POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
GEORGIA POWER CO | Transportation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
GEORGIA POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
GEORGIA POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
GEORGIA POWER CO | Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	69	56	147	186
GEORGIA POWER CO | Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	65	56	134	166
GEORGIA POWER CO | PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	31	40	66	112
GEORGIA POWER CO | PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	13	12	38	35
GEORGIA POWER CO | Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	21	4	30	19
GEORGIA POWER CO | Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
GEORGIA POWER CO | Gas marketing services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
GEORGIA POWER CO | Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
GEORGIA POWER CO | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	(151)	796	51	1,451
GEORGIA POWER CO | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	146	110	422	327
MISSISSIPPI POWER CO
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	440	531	1,123	1,276
Total operating revenues	436	510	1,137	1,279
MISSISSIPPI POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	284	250	747	718
MISSISSIPPI POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	288	271	733	716
MISSISSIPPI POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	101	93	238	238
MISSISSIPPI POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	95	87	238	229
MISSISSIPPI POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	90	89	251	242
MISSISSIPPI POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2	2	6	7
MISSISSIPPI POWER CO | Natural gas distribution revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
MISSISSIPPI POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
MISSISSIPPI POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
MISSISSIPPI POWER CO | Transportation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
MISSISSIPPI POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
MISSISSIPPI POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
MISSISSIPPI POWER CO | Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	142	247	359	526
MISSISSIPPI POWER CO | PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2	4	8	11
MISSISSIPPI POWER CO | PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3	1	36	4
MISSISSIPPI POWER CO | Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	137	242	315	511
MISSISSIPPI POWER CO | Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
MISSISSIPPI POWER CO | Gas marketing services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
MISSISSIPPI POWER CO | Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
MISSISSIPPI POWER CO | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	(4)	(21)	14	3
MISSISSIPPI POWER CO | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	10	13	31	34
SOUTHERN POWER CO
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	480	1,010	1,248	2,157
Total operating revenues	653	1,180	1,686	2,618
SOUTHERN POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN POWER CO | Natural gas distribution revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN POWER CO | Transportation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN POWER CO | Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	462	1,001	1,202	2,130
SOUTHERN POWER CO | PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	226	591	601	1,285
SOUTHERN POWER CO | PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	110	107	289	273
SOUTHERN POWER CO | Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	126	303	312	572
SOUTHERN POWER CO | Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN POWER CO | Gas marketing services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN POWER CO | Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN POWER CO | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	173	170	438	461
SOUTHERN POWER CO | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	18	9	46	27
SOUTHERN Co GAS
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	674	843	3,338	3,948
Total operating revenues	689	857	3,417	3,998
SOUTHERN Co GAS | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN Co GAS | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN Co GAS | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN Co GAS | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN Co GAS | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN Co GAS | Natural gas distribution revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	612	744	2,952	3,490
SOUTHERN Co GAS | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	217	331	1,443	1,821
SOUTHERN Co GAS | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	56	93	370	493
SOUTHERN Co GAS | Transportation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	275	259	878	872
SOUTHERN Co GAS | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	4	12	33	60
SOUTHERN Co GAS | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	60	49	228	244
SOUTHERN Co GAS | Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN Co GAS | PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN Co GAS | PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN Co GAS | Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN Co GAS | Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	62	99	386	458
SOUTHERN Co GAS | Gas marketing services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	54	84	358	417
SOUTHERN Co GAS | Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	8	15	28	41
SOUTHERN Co GAS | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	15	14	79	50
SOUTHERN Co GAS | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 0	$ 0	$ 0	$ 0

Revenue from Contracts with C_4

Revenue from Contracts with Customers and Lease Income - Schedule of Contract Balances (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Accounts Receivable	$ 2,680	$ 3,123
Contract Assets	267	156
Contract Liabilities	62	45
ALABAMA POWER CO
Disaggregation of Revenue [Line Items]
Accounts Receivable	858	696
Contract Assets	6	2
Contract Liabilities	0	4
GEORGIA POWER CO
Disaggregation of Revenue [Line Items]
Accounts Receivable	1,175	922
Contract Assets	146	89
Contract Liabilities	8	9
MISSISSIPPI POWER CO
Disaggregation of Revenue [Line Items]
Accounts Receivable	106	92
Contract Assets	0	0
Contract Liabilities	2	0
SOUTHERN POWER CO
Disaggregation of Revenue [Line Items]
Accounts Receivable	138	237
Contract Assets	0	0
Contract Liabilities	8	1
SOUTHERN Co GAS
Disaggregation of Revenue [Line Items]
Accounts Receivable	331	1,107
Contract Assets	41	0
Contract Liabilities	$ 0	$ 0

Revenue from Contracts with C_5

Revenue from Contracts with Customers and Lease Income - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Contract liabilities	$ 62	$ 62	$ 45
Contract assets	267	267	156
GEORGIA POWER CO
Disaggregation of Revenue [Line Items]
Contract liabilities	8	8	9
Contract assets	146	146	89
Revenue from contracts with customers recognized	0	0
SOUTHERN Co GAS
Disaggregation of Revenue [Line Items]
Contract liabilities	0	0	0
Contract assets	41	41	0
Revenue from contracts with customers recognized	0	0
ALABAMA POWER CO
Disaggregation of Revenue [Line Items]
Contract liabilities	0	0	4
Contract assets	6	6	2
Revenue from contracts with customers recognized	0	0
MISSISSIPPI POWER CO
Disaggregation of Revenue [Line Items]
Contract liabilities	2	2	0
Contract assets	0	0	0
Revenue from contracts with customers recognized	0	0
SOUTHERN POWER CO
Disaggregation of Revenue [Line Items]
Contract liabilities	8	8	1
Contract assets	0	0	0
Revenue from contracts with customers recognized	0	$ 0
Retail Customer Fixed Bill Programs | GEORGIA POWER CO
Disaggregation of Revenue [Line Items]
Contract term		1 year
Energy Efficiency Enhancement And Upgrade | SOUTHERN Co GAS
Disaggregation of Revenue [Line Items]
Contract liabilities	51	$ 51
Unregulated Distributed Generation
Disaggregation of Revenue [Line Items]
Contract liabilities	47	47	32
Contract assets	$ 75	$ 75	$ 65

Revenue from Contracts with C_6

Revenue from Contracts with Customers and Lease Income - Schedule of Remaining Performance Obligations (Details) $ in Millions	Sep. 30, 2023 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 166
Performance obligation, expected timing of satisfaction	3 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 599
Performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 359
Performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 318
Performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 319
Performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2028-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 2,245
Performance obligation, expected timing of satisfaction
ALABAMA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 10
Performance obligation, expected timing of satisfaction	3 months
ALABAMA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 24
Performance obligation, expected timing of satisfaction	1 year
ALABAMA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 8
Performance obligation, expected timing of satisfaction	1 year
ALABAMA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 0
Performance obligation, expected timing of satisfaction	1 year
ALABAMA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 0
Performance obligation, expected timing of satisfaction	1 year
ALABAMA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2028-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 0
Performance obligation, expected timing of satisfaction
GEORGIA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 23
Performance obligation, expected timing of satisfaction	3 months
GEORGIA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 66
Performance obligation, expected timing of satisfaction	1 year
GEORGIA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 34
Performance obligation, expected timing of satisfaction	1 year
GEORGIA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 14
Performance obligation, expected timing of satisfaction	1 year
GEORGIA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 14
Performance obligation, expected timing of satisfaction	1 year
GEORGIA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2028-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 23
Performance obligation, expected timing of satisfaction
SOUTHERN POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 84
Performance obligation, expected timing of satisfaction	3 months
SOUTHERN POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 356
Performance obligation, expected timing of satisfaction	1 year
SOUTHERN POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 302
Performance obligation, expected timing of satisfaction	1 year
SOUTHERN POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 303
Performance obligation, expected timing of satisfaction	1 year
SOUTHERN POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 310
Performance obligation, expected timing of satisfaction	1 year
SOUTHERN POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2028-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 2,233
Performance obligation, expected timing of satisfaction
SOUTHERN Co GAS | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 4
Performance obligation, expected timing of satisfaction	3 months
SOUTHERN Co GAS | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 29
Performance obligation, expected timing of satisfaction	1 year
SOUTHERN Co GAS | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 0
Performance obligation, expected timing of satisfaction	1 year
SOUTHERN Co GAS | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 0
Performance obligation, expected timing of satisfaction	1 year
SOUTHERN Co GAS | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 0
Performance obligation, expected timing of satisfaction	1 year
SOUTHERN Co GAS | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2028-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 0
Performance obligation, expected timing of satisfaction

Revenue from Contracts with C_7

Revenue from Contracts with Customers and Lease Income - Schedule of Lease Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Lessor, Lease, Description [Line Items]
Lease income - interest income on sales-type leases	$ 6	$ 7	$ 18	$ 19
Lease income - operating leases	36	50	129	149
Variable lease income	134	139	327	355
Total lease income	176	196	474	523
ALABAMA POWER CO
Lessor, Lease, Description [Line Items]
Lease income - interest income on sales-type leases	0	0	0	0
Lease income - operating leases	3	19	32	58
Variable lease income	0	0	1	1
Total lease income	3	19	33	59
GEORGIA POWER CO
Lessor, Lease, Description [Line Items]
Lease income - interest income on sales-type leases	0	0	0	0
Lease income - operating leases	7	8	22	24
Variable lease income	0	0	0	0
Total lease income	7	8	22	24
MISSISSIPPI POWER CO
Lessor, Lease, Description [Line Items]
Lease income - interest income on sales-type leases	4	4	11	11
Lease income - operating leases	0	1	2	1
Variable lease income	0	0	0	0
Total lease income	4	5	13	12
SOUTHERN POWER CO
Lessor, Lease, Description [Line Items]
Lease income - interest income on sales-type leases	2	3	7	8
Lease income - operating leases	21	21	64	64
Variable lease income	144	145	351	372
Total lease income	167	169	422	444
SOUTHERN Co GAS
Lessor, Lease, Description [Line Items]
Lease income - interest income on sales-type leases	0	0	0	0
Lease income - operating leases	9	9	27	27
Variable lease income	0	0	0	0
Total lease income	$ 9	$ 9	$ 27	$ 27

Consolidated Entities and Equ_3

Consolidated Entities and Equity Method Investments - Narrative (Details) $ in Millions	3 Months Ended	9 Months Ended
	Mar. 31, 2023 USD ($)	Sep. 30, 2023 USD ($) investor	Dec. 31, 2022 USD ($)
Schedule of Equity Method Investments [Line Items]
Equity investments in unconsolidated subsidiaries		$ 1,376	$ 1,443
Assets		138,321	134,891
Liabilities		103,017	100,359
Southern Holdings Company
Schedule of Equity Method Investments [Line Items]
Equity investments in unconsolidated subsidiaries		126	112
SOUTHERN POWER CO
Schedule of Equity Method Investments [Line Items]
Equity investments in unconsolidated subsidiaries		0	49
Assets		13,090	13,081
Liabilities		$ 6,247	6,165
Proceeds from sale of equity method investments	$ 50
SP Solar Holdings I, LP | SOUTHERN POWER CO
Schedule of Equity Method Investments [Line Items]
Distribution made to limited partner, cash distributions paid, percentage		67%
SP Solar Holdings I, LP | Global Atlantic
Schedule of Equity Method Investments [Line Items]
Distribution made to limited partner, cash distributions paid, percentage		33%
Variable Interest Entity, Primary Beneficiary | SP Solar Holdings I, LP | SOUTHERN POWER CO
Schedule of Equity Method Investments [Line Items]
Assets		$ 5,800	5,900
Liabilities		400	400
Noncontrolling interests related to other partners' interests		1,100
Variable Interest Entity, Primary Beneficiary | SP Wind | SOUTHERN POWER CO
Schedule of Equity Method Investments [Line Items]
Assets		2,200	2,200
Liabilities		184	169
Noncontrolling interests related to other partners' interests		$ 38	39
Distribution made to limited partner, cash distributions paid, percentage		60%
Number of financial investors | investor		3
Variable Interest Entity, Primary Beneficiary | SP Wind | Financial Investors
Schedule of Equity Method Investments [Line Items]
Distribution made to limited partner, cash distributions paid, percentage		40%
Variable Interest Entity, Primary Beneficiary | Other Variable Interest Entities | SOUTHERN POWER CO
Schedule of Equity Method Investments [Line Items]
Assets		$ 1,700	1,800
Liabilities		200	200
Noncontrolling interests related to other partners' interests		$ 800	$ 800

Consolidated Entities and Equ_4

Consolidated Entities and Equity Method Investments - Schedule of Equity Method Investments (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Schedule of Equity Method Investments [Line Items]
Investment Balance	$ 1,376	$ 1,443
SOUTHERN Co GAS
Schedule of Equity Method Investments [Line Items]
Investment Balance	1,243	1,276
SOUTHERN Co GAS | SNG
Schedule of Equity Method Investments [Line Items]
Investment Balance	1,210	1,243
SOUTHERN Co GAS | Other
Schedule of Equity Method Investments [Line Items]
Investment Balance	$ 33	$ 33

Consolidated Entities and Equ_5

Consolidated Entities and Equity Method Investments - Schedule of Earnings (Loss) from Equity Method Investments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Schedule of Equity Method Investments [Line Items]
Earnings from Equity Method Investments	$ 32	$ 28	$ 110	$ 109
SOUTHERN Co GAS
Schedule of Equity Method Investments [Line Items]
Earnings from Equity Method Investments	32	34	104	105
SOUTHERN Co GAS | SNG
Schedule of Equity Method Investments [Line Items]
Earnings from Equity Method Investments	32	34	104	104
SOUTHERN Co GAS | Other
Schedule of Equity Method Investments [Line Items]
Earnings from Equity Method Investments	$ 0	$ 0	$ 0	$ 1

Financing and Leases - Schedule

Financing and Leases - Schedule of Credit Arrangements (Details) - USD ($) $ in Millions	Sep. 30, 2023	Aug. 01, 2023	Jul. 31, 2023	Jun. 30, 2023	May 31, 2023	Apr. 30, 2023
Line of Credit Facility [Line Items]
Expires, 2024	$ 280
Expires, 2025	125
Expires, 2026	800
Expires, 2028	6,400
Total	7,605
Unused	7,566
Expires within One Year	280
Southern Company parent
Line of Credit Facility [Line Items]
Expires, 2024	150
Expires, 2025	0
Expires, 2026	0
Expires, 2028	1,850				$ 1,850
Total	2,000			$ 150
Unused	1,998
Expires within One Year	150
ALABAMA POWER CO
Line of Credit Facility [Line Items]
Expires, 2024	0
Expires, 2025	0
Expires, 2026	650
Expires, 2028	700
Total	1,350	$ 650	$ 550
Unused	1,350
Expires within One Year	0
GEORGIA POWER CO
Line of Credit Facility [Line Items]
Expires, 2024	0
Expires, 2025	0
Expires, 2026	0
Expires, 2028	1,750
Total	1,750
Unused	1,726
Expires within One Year	0
MISSISSIPPI POWER CO
Line of Credit Facility [Line Items]
Expires, 2024	0
Expires, 2025	125
Expires, 2026	150
Expires, 2028	0
Total	275				150
Unused	275
Expires within One Year	0
SOUTHERN POWER CO
Line of Credit Facility [Line Items]
Expires, 2024	0
Expires, 2025	0
Expires, 2026	0
Expires, 2028	600				600
Total	600
Unused	589
Expires within One Year	0
SOUTHERN POWER CO | Continuing Letter of Credit Facility A
Line of Credit Facility [Line Items]
Expires, 2025	75
Expires, 2026	100
Unused	9
SOUTHERN POWER CO | Continuing Letter of Credit Facility B
Line of Credit Facility [Line Items]
Unused	16
SOUTHERN Co GAS
Line of Credit Facility [Line Items]
Expires, 2024	100
Expires, 2025	0
Expires, 2026	0
Expires, 2028	1,500
Total	1,600
Unused	1,598
Expires within One Year	100
SEGCO
Line of Credit Facility [Line Items]
Expires, 2024	30
Expires, 2025	0
Expires, 2026	0
Expires, 2028	0
Total	30
Unused	30
Expires within One Year	30
Southern Company and Southern Power
Line of Credit Facility [Line Items]
Expires, 2028	2,450				2,450
Southern Company Gas Capital
Line of Credit Facility [Line Items]
Expires, 2028	800
Nicor Gas
Line of Credit Facility [Line Items]
Expires, 2024	100
Expires, 2028	$ 700
Total					$ 100	$ 250

Financing and Leases - Narrativ

Financing and Leases - Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2023	Aug. 01, 2023	Jul. 31, 2023	Jun. 30, 2023	May 31, 2023	Apr. 30, 2023
Debt Instrument [Line Items]
Expires, 2028	$ 6,400
Line of credit facility, maximum borrowing capacity	7,605
Variable rate pollution control revenue bonds outstanding	1,700
Southern Company and Southern Power
Debt Instrument [Line Items]
Expires, 2028	2,450				$ 2,450
Southern Company parent
Debt Instrument [Line Items]
Expires, 2028	1,850				1,850
Line of credit facility, maximum borrowing capacity	2,000			$ 150
SOUTHERN POWER CO
Debt Instrument [Line Items]
Expires, 2028	600				600
Line of credit facility, maximum borrowing capacity	600
MISSISSIPPI POWER CO
Debt Instrument [Line Items]
Expires, 2028	0
Line of credit facility, maximum borrowing capacity	275				150
Variable rate pollution control revenue bonds outstanding	69
Nicor Gas
Debt Instrument [Line Items]
Expires, 2028	700
Line of credit facility, maximum borrowing capacity					$ 100	$ 250
ALABAMA POWER CO
Debt Instrument [Line Items]
Expires, 2028	700
Line of credit facility, maximum borrowing capacity	1,350	$ 650	$ 550
Variable rate pollution control revenue bonds outstanding	818
Fixed rate pollution control revenue bonds outstanding	120
GEORGIA POWER CO
Debt Instrument [Line Items]
Expires, 2028	1,750
Line of credit facility, maximum borrowing capacity	1,750
Variable rate pollution control revenue bonds outstanding	819
Fixed rate pollution control revenue bonds outstanding	$ 325

Financing and Leases - Converti

Financing and Leases - Convertible Senior Notes (Details) - Series 2023A Convertible Senior Notes Due 2025 - Convertible Debt $ / shares in Units, $ in Millions		1 Months Ended
	Feb. 28, 2023 USD ($) $ / shares	Feb. 28, 2023 USD ($) d $ / shares	Mar. 31, 2023 USD ($)
Debt Instrument [Line Items]
Aggregate principal amount | $	$ 1,500	$ 1,500	$ 225
Interest rate	3.875%	3.875%
Conversion ratio		0.0118818
Conversion price (in dollars per share) | $ / shares	$ 84.16	$ 84.16
Redemption price	100%
Debt Conversion Terms One
Debt Instrument [Line Items]
Trading day threshold		20
Consecutive trading day threshold		30
Stock price trigger threshold, percentage		130%
Debt Conversion Terms Two
Debt Instrument [Line Items]
Trading day threshold		5
Consecutive trading day threshold		10
Stock price trigger threshold, percentage		98%

Financing and Leases - Schedu_2

Financing and Leases - Schedule of Shares Used to Compute Diluted Earnings Per Share (Details) - shares shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Debt Disclosure [Abstract]
As reported shares (in shares)	1,092	1,082	1,092	1,070
Effect of stock-based compensation (in shares)	7	6	6	6
Diluted (in shares)	1,099	1,088	1,098	1,076
Antidilutive securities excluded from computation of earnings per share (in shares)	0	0	0	0

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Income Tax Contingency [Line Items]
Effective tax (benefit) rate		13.90%	20%
ALABAMA POWER CO
Income Tax Contingency [Line Items]
Effective tax (benefit) rate		8.30%	23.70%
GEORGIA POWER CO
Income Tax Contingency [Line Items]
Effective tax (benefit) rate		18.20%	18.50%
Unrecognized tax positions		$ 86
MISSISSIPPI POWER CO
Income Tax Contingency [Line Items]
Effective tax (benefit) rate		16.90%	20.10%
SOUTHERN POWER CO
Income Tax Contingency [Line Items]
Effective tax (benefit) rate		14.80%	18.80%
SOUTHERN POWER CO | ITC and PTC carryforwards
Income Tax Contingency [Line Items]
Deferred tax assets		$ 1,000		$ 1,100
Southern Company parent
Income Tax Contingency [Line Items]
Unrecognized tax positions		$ 167		$ 80
Southern Company parent | Scenario, Forecast
Income Tax Contingency [Line Items]
Tax position as a result of expiration of statue of limitations	$ 44

Retirement Benefits (Details)

Retirement Benefits (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, expected future employer contributions, remainder of fiscal year	$ 0		$ 0
Pension Plans and Postretirement Plans
Service cost	69,000,000	$ 103,000,000	207,000,000	$ 309,000,000
Interest cost	156,000,000	102,000,000	469,000,000	306,000,000
Expected return on plan assets	(307,000,000)	(316,000,000)	(922,000,000)	(949,000,000)
Amortization:
Prior service costs	0	0	0	0
Regulatory asset	0	0	0	0
Net (gain) loss	8,000,000	60,000,000	24,000,000	180,000,000
Net periodic pension income	(74,000,000)	(51,000,000)	(222,000,000)	(154,000,000)
Pension Plans | ALABAMA POWER CO
Pension Plans and Postretirement Plans
Service cost	16,000,000	25,000,000	48,000,000	74,000,000
Interest cost	37,000,000	24,000,000	109,000,000	72,000,000
Expected return on plan assets	(75,000,000)	(77,000,000)	(223,000,000)	(229,000,000)
Amortization:
Prior service costs	0	0	0	0
Regulatory asset	0	0	0	0
Net (gain) loss	2,000,000	16,000,000	7,000,000	47,000,000
Net periodic pension income	(20,000,000)	(12,000,000)	(59,000,000)	(36,000,000)
Pension Plans | GEORGIA POWER CO
Pension Plans and Postretirement Plans
Service cost	17,000,000	26,000,000	51,000,000	78,000,000
Interest cost	48,000,000	31,000,000	143,000,000	92,000,000
Expected return on plan assets	(97,000,000)	(99,000,000)	(289,000,000)	(298,000,000)
Amortization:
Prior service costs	0	0	1,000,000	1,000,000
Regulatory asset	0	0	0	0
Net (gain) loss	4,000,000	18,000,000	10,000,000	55,000,000
Net periodic pension income	(28,000,000)	(24,000,000)	(84,000,000)	(72,000,000)
Pension Plans | MISSISSIPPI POWER CO
Pension Plans and Postretirement Plans
Service cost	2,000,000	5,000,000	8,000,000	13,000,000
Interest cost	7,000,000	5,000,000	21,000,000	14,000,000
Expected return on plan assets	(13,000,000)	(15,000,000)	(41,000,000)	(44,000,000)
Amortization:
Prior service costs	0	0	0	0
Regulatory asset	0	0	0	0
Net (gain) loss	1,000,000	2,000,000	1,000,000	9,000,000
Net periodic pension income	(3,000,000)	(3,000,000)	(11,000,000)	(8,000,000)
Pension Plans | SOUTHERN POWER CO
Pension Plans and Postretirement Plans
Service cost	2,000,000	2,000,000	5,000,000	7,000,000
Interest cost	2,000,000	2,000,000	6,000,000	5,000,000
Expected return on plan assets	(4,000,000)	(4,000,000)	(12,000,000)	(12,000,000)
Amortization:
Prior service costs	0	0	0	0
Regulatory asset	0	0	0	0
Net (gain) loss	0	1,000,000	0	2,000,000
Net periodic pension income	0	1,000,000	(1,000,000)	2,000,000
Pension Plans | SOUTHERN Co GAS
Pension Plans and Postretirement Plans
Service cost	6,000,000	9,000,000	18,000,000	26,000,000
Interest cost	11,000,000	7,000,000	32,000,000	21,000,000
Expected return on plan assets	(22,000,000)	(22,000,000)	(65,000,000)	(68,000,000)
Amortization:
Prior service costs	(1,000,000)	(1,000,000)	(2,000,000)	(2,000,000)
Regulatory asset	4,000,000	3,000,000	11,000,000	11,000,000
Net (gain) loss	(1,000,000)	2,000,000	(3,000,000)	5,000,000
Net periodic pension income	(3,000,000)	(2,000,000)	(9,000,000)	(7,000,000)
Postretirement Benefits
Pension Plans and Postretirement Plans
Service cost	4,000,000	6,000,000	11,000,000	17,000,000
Interest cost	18,000,000	10,000,000	53,000,000	31,000,000
Expected return on plan assets	(21,000,000)	(20,000,000)	(62,000,000)	(60,000,000)
Amortization:
Prior service costs	0	(1,000,000)	1,000,000	(1,000,000)
Regulatory asset	0	0	0	0
Net (gain) loss	(4,000,000)	1,000,000	(10,000,000)	1,000,000
Net periodic pension income	(3,000,000)	(4,000,000)	(7,000,000)	(12,000,000)
Postretirement Benefits | ALABAMA POWER CO
Pension Plans and Postretirement Plans
Service cost	1,000,000	2,000,000	3,000,000	5,000,000
Interest cost	5,000,000	3,000,000	13,000,000	8,000,000
Expected return on plan assets	(9,000,000)	(9,000,000)	(26,000,000)	(25,000,000)
Amortization:
Prior service costs	0	0	0	0
Regulatory asset	0	0	0	0
Net (gain) loss	(1,000,000)	0	(2,000,000)	0
Net periodic pension income	(4,000,000)	(4,000,000)	(12,000,000)	(12,000,000)
Postretirement Benefits | GEORGIA POWER CO
Pension Plans and Postretirement Plans
Service cost	1,000,000	2,000,000	3,000,000	5,000,000
Interest cost	6,000,000	4,000,000	19,000,000	11,000,000
Expected return on plan assets	(7,000,000)	(8,000,000)	(22,000,000)	(21,000,000)
Amortization:
Prior service costs	1,000,000	0	1,000,000	0
Regulatory asset	0	0	0	0
Net (gain) loss	(1,000,000)	0	(3,000,000)	1,000,000
Net periodic pension income	0	(2,000,000)	(2,000,000)	(4,000,000)
Postretirement Benefits | MISSISSIPPI POWER CO
Pension Plans and Postretirement Plans
Service cost	0	1,000,000	0	1,000,000
Interest cost	1,000,000	0	2,000,000	1,000,000
Expected return on plan assets	(1,000,000)	0	(1,000,000)	(1,000,000)
Amortization:
Prior service costs	0	0	0	0
Regulatory asset	0	0	0	0
Net (gain) loss	0	0	0	0
Net periodic pension income	0	1,000,000	1,000,000	1,000,000
Postretirement Benefits | SOUTHERN POWER CO
Pension Plans and Postretirement Plans
Service cost	0	1,000,000	0	1,000,000
Interest cost	0	0	0	0
Expected return on plan assets	0	0	0	0
Amortization:
Prior service costs	0	0	0	0
Regulatory asset	0	0	0	0
Net (gain) loss	0	0	0	0
Net periodic pension income	0	1,000,000	0	1,000,000
Postretirement Benefits | SOUTHERN Co GAS
Pension Plans and Postretirement Plans
Service cost	0	0	1,000,000	1,000,000
Interest cost	2,000,000	1,000,000	6,000,000	4,000,000
Expected return on plan assets	(2,000,000)	(2,000,000)	(5,000,000)	(6,000,000)
Amortization:
Prior service costs	0	0	0	0
Regulatory asset	2,000,000	2,000,000	5,000,000	5,000,000
Net (gain) loss	(1,000,000)	(1,000,000)	(3,000,000)	(2,000,000)
Net periodic pension income	$ 1,000,000	$ 0	$ 4,000,000	$ 2,000,000

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Assets:
Derivatives	$ 43	$ 141
Liabilities:
Derivatives	708	617
Other	13
Collateral already posted, assets, aggregate fair value	49
Quoted Prices in Active Markets for Identical Assets (Level 1)
Liabilities:
Other	0
Significant Other Observable Inputs (Level 2)
Liabilities:
Other	13
Significant Unobservable Inputs (Level 3)
Liabilities:
Other	0
ALABAMA POWER CO
Assets:
Derivatives	9	38
Liabilities:
Derivatives	58	15
Collateral already posted, assets, aggregate fair value	0
GEORGIA POWER CO
Assets:
Derivatives	3	21
Liabilities:
Derivatives	72	41
MISSISSIPPI POWER CO
Assets:
Derivatives	7	42
Liabilities:
Derivatives	27	15
SOUTHERN POWER CO
Assets:
Derivatives	4	8
Liabilities:
Derivatives	47	59
Other	13
Collateral already posted, assets, aggregate fair value	18
SOUTHERN POWER CO | Quoted Prices in Active Markets for Identical Assets (Level 1)
Liabilities:
Other	0
SOUTHERN POWER CO | Significant Other Observable Inputs (Level 2)
Liabilities:
Other	13
SOUTHERN POWER CO | Significant Unobservable Inputs (Level 3)
Liabilities:
Other	0
SOUTHERN Co GAS
Assets:
Derivatives	20	28
Liabilities:
Derivatives	102	110
Total
Collateral already posted, assets, aggregate fair value	49	$ 41
Fair Value, Measurements, Recurring
Assets:
Cash equivalents and restricted cash	930
Other investments	51
Total	3,288
Liabilities:
Contingent consideration	24
Total	831
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash equivalents and restricted cash	919
Other investments	9
Total	1,794
Liabilities:
Contingent consideration	5
Total	39
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Assets:
Cash equivalents and restricted cash	11
Other investments	34
Total	1,309
Liabilities:
Contingent consideration	0
Total	773
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents and restricted cash	0
Other investments	8
Total	8
Liabilities:
Contingent consideration	19
Total	19
Fair Value, Measurements, Recurring | Net Asset Value as a Practical Expedient (NAV)
Assets:
Total	177
Fair Value, Measurements, Recurring | Energy-related derivatives
Assets:
Derivatives	80
Liabilities:
Derivatives	251
Fair Value, Measurements, Recurring | Energy-related derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Derivatives	7
Liabilities:
Derivatives	34
Fair Value, Measurements, Recurring | Energy-related derivatives | Significant Other Observable Inputs (Level 2)
Assets:
Derivatives	73
Liabilities:
Derivatives	217
Fair Value, Measurements, Recurring | Energy-related derivatives | Significant Unobservable Inputs (Level 3)
Assets:
Derivatives	0
Liabilities:
Derivatives	0
Fair Value, Measurements, Recurring | Interest rate derivatives
Liabilities:
Derivatives	351
Fair Value, Measurements, Recurring | Interest rate derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)
Liabilities:
Derivatives	0
Fair Value, Measurements, Recurring | Interest rate derivatives | Significant Other Observable Inputs (Level 2)
Liabilities:
Derivatives	351
Fair Value, Measurements, Recurring | Interest rate derivatives | Significant Unobservable Inputs (Level 3)
Liabilities:
Derivatives	0
Fair Value, Measurements, Recurring | Domestic equity
Assets:
Investments in trusts	888
Fair Value, Measurements, Recurring | Domestic equity | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	692
Fair Value, Measurements, Recurring | Domestic equity | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	196
Fair Value, Measurements, Recurring | Domestic equity | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | Foreign equity
Assets:
Investments in trusts	285
Fair Value, Measurements, Recurring | Foreign equity | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	131
Fair Value, Measurements, Recurring | Foreign equity | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	154
Fair Value, Measurements, Recurring | Foreign equity | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | U.S. Treasury and government agency securities
Assets:
Investments in trusts	337
Fair Value, Measurements, Recurring | U.S. Treasury and government agency securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | U.S. Treasury and government agency securities | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	337
Fair Value, Measurements, Recurring | U.S. Treasury and government agency securities | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | Municipal bonds
Assets:
Investments in trusts	42
Fair Value, Measurements, Recurring | Municipal bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | Municipal bonds | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	42
Fair Value, Measurements, Recurring | Municipal bonds | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | Pooled funds – fixed income
Assets:
Investments in trusts	6
Fair Value, Measurements, Recurring | Pooled funds – fixed income | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | Pooled funds – fixed income | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	6
Fair Value, Measurements, Recurring | Pooled funds – fixed income | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | Corporate bonds
Assets:
Investments in trusts	368
Fair Value, Measurements, Recurring | Corporate bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | Corporate bonds | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	368
Fair Value, Measurements, Recurring | Corporate bonds | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | Mortgage and asset backed securities
Assets:
Investments in trusts	85
Fair Value, Measurements, Recurring | Mortgage and asset backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | Mortgage and asset backed securities | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	85
Fair Value, Measurements, Recurring | Mortgage and asset backed securities | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | Private equity
Assets:
Investments in trusts	169
Fair Value, Measurements, Recurring | Private equity | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | Private equity | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | Private equity | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | Private equity | Net Asset Value as a Practical Expedient (NAV)
Assets:
Investments in trusts	169
Fair Value, Measurements, Recurring | Cash and cash equivalents
Assets:
Investments in trusts	3
Fair Value, Measurements, Recurring | Cash and cash equivalents | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	3
Fair Value, Measurements, Recurring | Cash and cash equivalents | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | Cash and cash equivalents | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | Other
Assets:
Investments in trusts	44
Fair Value, Measurements, Recurring | Other | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	33
Fair Value, Measurements, Recurring | Other | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	3
Fair Value, Measurements, Recurring | Other | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | Other | Net Asset Value as a Practical Expedient (NAV)
Assets:
Investments in trusts	8
Fair Value, Measurements, Recurring | Foreign currency derivatives
Liabilities:
Derivatives	192
Fair Value, Measurements, Recurring | Foreign currency derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)
Liabilities:
Derivatives	0
Fair Value, Measurements, Recurring | Foreign currency derivatives | Significant Other Observable Inputs (Level 2)
Liabilities:
Derivatives	192
Fair Value, Measurements, Recurring | Foreign currency derivatives | Significant Unobservable Inputs (Level 3)
Liabilities:
Derivatives	0
Fair Value, Measurements, Recurring | ALABAMA POWER CO
Assets:
Cash equivalents and restricted cash	500
Other investments	34
Total	1,728
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash equivalents and restricted cash	489
Other investments	0
Total	1,034
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Significant Other Observable Inputs (Level 2)
Assets:
Cash equivalents and restricted cash	11
Other investments	34
Total	517
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents and restricted cash	0
Other investments	0
Total	0
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Net Asset Value as a Practical Expedient (NAV)
Assets:
Total	177
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Energy-related derivatives
Assets:
Derivatives	26
Liabilities:
Derivatives	75
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Energy-related derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Derivatives	0
Liabilities:
Derivatives	0
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Energy-related derivatives | Significant Other Observable Inputs (Level 2)
Assets:
Derivatives	26
Liabilities:
Derivatives	75
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Energy-related derivatives | Significant Unobservable Inputs (Level 3)
Assets:
Derivatives	0
Liabilities:
Derivatives	0
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Domestic equity
Assets:
Investments in trusts	592
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Domestic equity | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	404
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Domestic equity | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	188
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Domestic equity | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Foreign equity
Assets:
Investments in trusts	131
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Foreign equity | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	131
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Foreign equity | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Foreign equity | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | ALABAMA POWER CO | U.S. Treasury and government agency securities
Assets:
Investments in trusts	20
Fair Value, Measurements, Recurring | ALABAMA POWER CO | U.S. Treasury and government agency securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | ALABAMA POWER CO | U.S. Treasury and government agency securities | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	20
Fair Value, Measurements, Recurring | ALABAMA POWER CO | U.S. Treasury and government agency securities | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Municipal bonds
Assets:
Investments in trusts	1
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Municipal bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Municipal bonds | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	1
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Municipal bonds | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Corporate bonds
Assets:
Investments in trusts	215
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Corporate bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Corporate bonds | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	215
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Corporate bonds | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Mortgage and asset backed securities
Assets:
Investments in trusts	22
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Mortgage and asset backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Mortgage and asset backed securities | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	22
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Mortgage and asset backed securities | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Private equity
Assets:
Investments in trusts	169
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Private equity | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Private equity | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Private equity | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Private equity | Net Asset Value as a Practical Expedient (NAV)
Assets:
Investments in trusts	169
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Other
Assets:
Investments in trusts	18
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Other | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	10
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Other | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Other | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | ALABAMA POWER CO | Other | Net Asset Value as a Practical Expedient (NAV)
Assets:
Investments in trusts	8
Fair Value, Measurements, Recurring | GEORGIA POWER CO
Assets:
Total	1,056
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Total	311
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Significant Other Observable Inputs (Level 2)
Assets:
Total	745
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Significant Unobservable Inputs (Level 3)
Assets:
Total	0
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Energy-related derivatives
Assets:
Derivatives	14
Liabilities:
Derivatives	83
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Energy-related derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Derivatives	0
Liabilities:
Derivatives	0
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Energy-related derivatives | Significant Other Observable Inputs (Level 2)
Assets:
Derivatives	14
Liabilities:
Derivatives	83
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Energy-related derivatives | Significant Unobservable Inputs (Level 3)
Assets:
Derivatives	0
Liabilities:
Derivatives	0
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Domestic equity
Assets:
Investments in trusts	289
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Domestic equity | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	288
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Domestic equity | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	1
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Domestic equity | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Foreign equity
Assets:
Investments in trusts	153
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Foreign equity | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Foreign equity | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	153
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Foreign equity | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | GEORGIA POWER CO | U.S. Treasury and government agency securities
Assets:
Investments in trusts	317
Fair Value, Measurements, Recurring | GEORGIA POWER CO | U.S. Treasury and government agency securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | GEORGIA POWER CO | U.S. Treasury and government agency securities | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	317
Fair Value, Measurements, Recurring | GEORGIA POWER CO | U.S. Treasury and government agency securities | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Municipal bonds
Assets:
Investments in trusts	41
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Municipal bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Municipal bonds | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	41
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Municipal bonds | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Corporate bonds
Assets:
Investments in trusts	153
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Corporate bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Corporate bonds | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	153
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Corporate bonds | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Mortgage and asset backed securities
Assets:
Investments in trusts	63
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Mortgage and asset backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Mortgage and asset backed securities | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	63
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Mortgage and asset backed securities | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Other
Assets:
Investments in trusts	26
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Other | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments in trusts	23
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Other | Significant Other Observable Inputs (Level 2)
Assets:
Investments in trusts	3
Fair Value, Measurements, Recurring | GEORGIA POWER CO | Other | Significant Unobservable Inputs (Level 3)
Assets:
Investments in trusts	0
Fair Value, Measurements, Recurring | MISSISSIPPI POWER CO
Assets:
Cash equivalents and restricted cash	3
Total	27
Fair Value, Measurements, Recurring | MISSISSIPPI POWER CO | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash equivalents and restricted cash	3
Total	3
Fair Value, Measurements, Recurring | MISSISSIPPI POWER CO | Significant Other Observable Inputs (Level 2)
Assets:
Cash equivalents and restricted cash	0
Total	24
Fair Value, Measurements, Recurring | MISSISSIPPI POWER CO | Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents and restricted cash	0
Total	0
Fair Value, Measurements, Recurring | MISSISSIPPI POWER CO | Energy-related derivatives
Assets:
Derivatives	24
Liabilities:
Derivatives	44
Fair Value, Measurements, Recurring | MISSISSIPPI POWER CO | Energy-related derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Derivatives	0
Liabilities:
Derivatives	0
Fair Value, Measurements, Recurring | MISSISSIPPI POWER CO | Energy-related derivatives | Significant Other Observable Inputs (Level 2)
Assets:
Derivatives	24
Liabilities:
Derivatives	44
Fair Value, Measurements, Recurring | MISSISSIPPI POWER CO | Energy-related derivatives | Significant Unobservable Inputs (Level 3)
Assets:
Derivatives	0
Liabilities:
Derivatives	0
Fair Value, Measurements, Recurring | SOUTHERN POWER CO
Assets:
Cash equivalents and restricted cash	23
Total	28
Liabilities:
Contingent consideration	24
Total	85
Fair Value, Measurements, Recurring | SOUTHERN POWER CO | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash equivalents and restricted cash	23
Total	23
Liabilities:
Contingent consideration	5
Total	5
Fair Value, Measurements, Recurring | SOUTHERN POWER CO | Significant Other Observable Inputs (Level 2)
Assets:
Cash equivalents and restricted cash	0
Total	5
Liabilities:
Contingent consideration	0
Total	61
Fair Value, Measurements, Recurring | SOUTHERN POWER CO | Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents and restricted cash	0
Total	0
Liabilities:
Contingent consideration	19
Total	19
Fair Value, Measurements, Recurring | SOUTHERN POWER CO | Energy-related derivatives
Assets:
Derivatives	5
Liabilities:
Derivatives	6
Fair Value, Measurements, Recurring | SOUTHERN POWER CO | Energy-related derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Derivatives	0
Liabilities:
Derivatives	0
Fair Value, Measurements, Recurring | SOUTHERN POWER CO | Energy-related derivatives | Significant Other Observable Inputs (Level 2)
Assets:
Derivatives	5
Liabilities:
Derivatives	6
Fair Value, Measurements, Recurring | SOUTHERN POWER CO | Energy-related derivatives | Significant Unobservable Inputs (Level 3)
Assets:
Derivatives	0
Liabilities:
Derivatives	0
Fair Value, Measurements, Recurring | SOUTHERN POWER CO | Foreign currency derivatives
Liabilities:
Derivatives	42
Fair Value, Measurements, Recurring | SOUTHERN POWER CO | Foreign currency derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)
Liabilities:
Derivatives	0
Fair Value, Measurements, Recurring | SOUTHERN POWER CO | Foreign currency derivatives | Significant Other Observable Inputs (Level 2)
Liabilities:
Derivatives	42
Fair Value, Measurements, Recurring | SOUTHERN POWER CO | Foreign currency derivatives | Significant Unobservable Inputs (Level 3)
Liabilities:
Derivatives	0
Fair Value, Measurements, Recurring | SOUTHERN Co GAS
Assets:
Cash equivalents and restricted cash	294
Total	322
Liabilities:
Total	142
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash equivalents and restricted cash	294
Total	304
Liabilities:
Total	34
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Significant Other Observable Inputs (Level 2)
Assets:
Cash equivalents and restricted cash	0
Total	18
Liabilities:
Total	108
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents and restricted cash	0
Total	0
Liabilities:
Total	0
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Energy-related derivatives
Assets:
Derivatives	11
Liabilities:
Derivatives	43
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Energy-related derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Derivatives	7
Liabilities:
Derivatives	34
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Energy-related derivatives | Significant Other Observable Inputs (Level 2)
Assets:
Derivatives	4
Liabilities:
Derivatives	9
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Energy-related derivatives | Significant Unobservable Inputs (Level 3)
Assets:
Derivatives	0
Liabilities:
Derivatives	0
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Interest rate derivatives
Liabilities:
Derivatives	99
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Interest rate derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)
Liabilities:
Derivatives	0
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Interest rate derivatives | Significant Other Observable Inputs (Level 2)
Liabilities:
Derivatives	99
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Interest rate derivatives | Significant Unobservable Inputs (Level 3)
Liabilities:
Derivatives	0
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Domestic equity
Assets:
Non-qualified deferred compensation trusts	7
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Domestic equity | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Non-qualified deferred compensation trusts	0
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Domestic equity | Significant Other Observable Inputs (Level 2)
Assets:
Non-qualified deferred compensation trusts	7
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Domestic equity | Significant Unobservable Inputs (Level 3)
Assets:
Non-qualified deferred compensation trusts	0
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Foreign equity
Assets:
Non-qualified deferred compensation trusts	1
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Foreign equity | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Non-qualified deferred compensation trusts	0
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Foreign equity | Significant Other Observable Inputs (Level 2)
Assets:
Non-qualified deferred compensation trusts	1
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Foreign equity | Significant Unobservable Inputs (Level 3)
Assets:
Non-qualified deferred compensation trusts	0
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Pooled funds – fixed income
Assets:
Non-qualified deferred compensation trusts	6
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Pooled funds – fixed income | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Non-qualified deferred compensation trusts	0
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Pooled funds – fixed income | Significant Other Observable Inputs (Level 2)
Assets:
Non-qualified deferred compensation trusts	6
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Pooled funds – fixed income | Significant Unobservable Inputs (Level 3)
Assets:
Non-qualified deferred compensation trusts	0
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Cash equivalents
Assets:
Non-qualified deferred compensation trusts	3
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Cash equivalents | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Non-qualified deferred compensation trusts	3
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Cash equivalents | Significant Other Observable Inputs (Level 2)
Assets:
Non-qualified deferred compensation trusts	0
Fair Value, Measurements, Recurring | SOUTHERN Co GAS | Cash equivalents | Significant Unobservable Inputs (Level 3)
Assets:
Non-qualified deferred compensation trusts	$ 0

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Increase (Decrease) In Fair Value Of Funds (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Fair Value, Option, Quantitative Disclosures [Line Items]
Increase (decrease) in fair value of funds	$ (4)	$ (106)	$ 211	$ (486)
ALABAMA POWER CO
Fair Value, Option, Quantitative Disclosures [Line Items]
Increase (decrease) in fair value of funds	(36)	(53)	54	(245)
GEORGIA POWER CO
Fair Value, Option, Quantitative Disclosures [Line Items]
Increase (decrease) in fair value of funds	$ 32	$ (53)	$ 157	$ (241)

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - ALABAMA POWER CO - Private equity $ in Millions	Sep. 30, 2023 USD ($)
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair value	$ 177
Unfunded commitments	$ 72

Fair Value Measurements - Sch_3

Fair Value Measurements - Schedule of Financial Instruments for which Carrying Amount did not Equal Fair Value (Details) $ in Billions	Sep. 30, 2023 USD ($)
Long-term debt, including securities due within one year:
Carrying amount	$ 58.8
Fair value	50.8
ALABAMA POWER CO
Long-term debt, including securities due within one year:
Carrying amount	11.2
Fair value	9.4
GEORGIA POWER CO
Long-term debt, including securities due within one year:
Carrying amount	15.8
Fair value	13.4
MISSISSIPPI POWER CO
Long-term debt, including securities due within one year:
Carrying amount	1.6
Fair value	1.3
SOUTHERN POWER CO
Long-term debt, including securities due within one year:
Carrying amount	2.7
Fair value	2.4
SOUTHERN Co GAS
Long-term debt, including securities due within one year:
Carrying amount	8.1
Fair value	$ 6.5

Derivatives - Schedule of Energ

Derivatives - Schedule of Energy-Related Derivatives (Details) - Energy-related, Natural Gas MMBTU in Millions	Sep. 30, 2023 MMBTU
Energy-related derivative contracts
Net Purchased mmBtu	422
ALABAMA POWER CO
Energy-related derivative contracts
Net Purchased mmBtu	109
GEORGIA POWER CO
Energy-related derivative contracts
Net Purchased mmBtu	104
MISSISSIPPI POWER CO
Energy-related derivative contracts
Net Purchased mmBtu	80
SOUTHERN POWER CO
Energy-related derivative contracts
Net Purchased mmBtu	8
SOUTHERN Co GAS
Energy-related derivative contracts
Net Purchased mmBtu	121
SOUTHERN Co GAS | Energy-related derivatives not designated as hedging instruments | Long
Energy-related derivative contracts
Derivative nonmonetary notional amount net long short position volume	135.5
SOUTHERN Co GAS | Energy-related derivatives not designated as hedging instruments | Short
Energy-related derivative contracts
Derivative nonmonetary notional amount net long short position volume	14.2

Derivatives - Narrative (Detail

Derivatives - Narrative (Details) MMBTU in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) MMBTU	Sep. 30, 2022 USD ($)	Sep. 30, 2024 USD ($)	Dec. 31, 2022 USD ($)
Derivative [Line Items]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints | MMBTU			14
Gain (Loss) Recognized in OCI on Derivatives	$ 5,000,000	$ 2,000,000	$ (45,000,000)	$ (32,000,000)
Collateral already posted, assets, aggregate fair value	49,000,000		49,000,000
Derivatives	708,000,000		708,000,000			$ 617,000,000
Scenario, Forecast
Derivative [Line Items]
Energy-related derivative hedge gain (loss) to be reclassified within twelve months					$ 30,000,000
Interest rate derivatives
Derivative [Line Items]
Derivatives	78,000,000		78,000,000
Interest rate derivatives | Scenario, Forecast
Derivative [Line Items]
Cash flow hedge gain (loss) to be reclassified within twelve months					19,000,000
Interest rate derivatives | Cash Flow Hedging
Derivative [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	(3,000,000)	6,000,000	(12,000,000)	36,000,000
Interest rate derivatives | Cash Flow Hedging | Interest Expense
Derivative [Line Items]
Gain (loss) on hedges	(22,000,000)	(7,000,000)	(31,000,000)	(19,000,000)
Interest rate derivatives | Fair Value Hedging | Interest Expense
Derivative [Line Items]
Gain (loss) on hedges	(47,000,000)	(102,000,000)	(50,000,000)	(300,000,000)
Energy-related derivatives | Energy-related derivatives not designated as hedging instruments
Derivative [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	7,000,000	1,000,000	36,000,000	(17,000,000)
Energy-related derivatives | Cash Flow Hedging
Derivative [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	(4,000,000)	11,000,000	$ (55,000,000)	51,000,000
SOUTHERN POWER CO
Derivative [Line Items]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints | MMBTU			3
Gain (Loss) Recognized in OCI on Derivatives	(15,000,000)	(46,000,000)	$ (20,000,000)	(141,000,000)
Collateral already posted, assets, aggregate fair value	18,000,000		18,000,000
Derivatives	47,000,000		47,000,000			59,000,000
SOUTHERN POWER CO | Scenario, Forecast
Derivative [Line Items]
Foreign currency cash flow hedge gain (loss to be reclassified					10,000,000
SOUTHERN POWER CO | Interest rate derivatives
Derivative [Line Items]
Derivatives	20,000,000		20,000,000
SOUTHERN POWER CO | Interest rate derivatives | Scenario, Forecast
Derivative [Line Items]
Cash flow hedge gain (loss) to be reclassified within twelve months					0
SOUTHERN POWER CO | Energy-related derivatives | Energy-related derivatives not designated as hedging instruments
Derivative [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	0	0	0	0
SOUTHERN POWER CO | Energy-related derivatives | Cash Flow Hedging
Derivative [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	0	(11,000,000)	(14,000,000)	(4,000,000)
SOUTHERN Co GAS
Derivative [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	(8,000,000)	27,000,000	(41,000,000)	55,000,000
Collateral already posted, assets, aggregate fair value	49,000,000		49,000,000			41,000,000
Derivatives	102,000,000		102,000,000			110,000,000
SOUTHERN Co GAS | Scenario, Forecast
Derivative [Line Items]
Energy-related derivative hedge gain (loss) to be reclassified within twelve months					25,000,000
SOUTHERN Co GAS | Interest rate derivatives | Scenario, Forecast
Derivative [Line Items]
Cash flow hedge gain (loss) to be reclassified within twelve months					0
SOUTHERN Co GAS | Interest rate derivatives | Cash Flow Hedging
Derivative [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	(4,000,000)	5,000,000	0	0
SOUTHERN Co GAS | Interest rate derivatives | Cash Flow Hedging | Interest Expense
Derivative [Line Items]
Gain (loss) on hedges	(18,000,000)	(2,000,000)	(18,000,000)	(3,000,000)
SOUTHERN Co GAS | Interest rate derivatives | Fair Value Hedging | Interest Expense
Derivative [Line Items]
Gain (loss) on hedges	(11,000,000)	(30,000,000)	(14,000,000)	(87,000,000)
SOUTHERN Co GAS | Energy-related derivatives | Cash Flow Hedging
Derivative [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	(4,000,000)	22,000,000	$ (41,000,000)	55,000,000
ALABAMA POWER CO
Derivative [Line Items]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints | MMBTU			4
Collateral already posted, assets, aggregate fair value	0		$ 0
Derivatives	58,000,000		58,000,000			15,000,000
ALABAMA POWER CO | Interest rate derivatives | Scenario, Forecast
Derivative [Line Items]
Cash flow hedge gain (loss) to be reclassified within twelve months					0
ALABAMA POWER CO | Energy-related derivatives | Energy-related derivatives not designated as hedging instruments
Derivative [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	0	0	0	0
ALABAMA POWER CO | Energy-related derivatives | Cash Flow Hedging
Derivative [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	0	0	$ 0	0
GEORGIA POWER CO
Derivative [Line Items]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints | MMBTU			5
Derivatives	72,000,000		$ 72,000,000			41,000,000
GEORGIA POWER CO | Interest rate derivatives | Scenario, Forecast
Derivative [Line Items]
Cash flow hedge gain (loss) to be reclassified within twelve months					0
GEORGIA POWER CO | Interest rate derivatives | Cash Flow Hedging
Derivative [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	0	0	(3,000,000)	31,000,000
GEORGIA POWER CO | Energy-related derivatives | Energy-related derivatives not designated as hedging instruments
Derivative [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	0	0	$ 0	0
MISSISSIPPI POWER CO
Derivative [Line Items]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints | MMBTU			2
Derivatives	27,000,000		$ 27,000,000			$ 15,000,000
MISSISSIPPI POWER CO | Interest rate derivatives | Scenario, Forecast
Derivative [Line Items]
Cash flow hedge gain (loss) to be reclassified within twelve months					$ 0
MISSISSIPPI POWER CO | Energy-related derivatives | Energy-related derivatives not designated as hedging instruments
Derivative [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	0	0	0	0
MISSISSIPPI POWER CO | Energy-related derivatives | Cash Flow Hedging
Derivative [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	0	0	0	0
Registrants | Derivative Counterparties
Derivative [Line Items]
Collateral already posted, assets, aggregate fair value	0		0
Traditional Electric Operating Companies | Interest rate derivatives | Cash Flow Hedging | Interest Expense
Derivative [Line Items]
Gain (loss) on hedges	0	0	0	0
Traditional Electric Operating Companies | Interest rate derivatives | Fair Value Hedging | Interest Expense
Derivative [Line Items]
Gain (loss) on hedges	$ 0	$ 0	$ 0	$ 0

Derivatives - Schedule of Inter

Derivatives - Schedule of Interest Rate Derivatives (Details) - Interest rate derivatives $ in Millions	9 Months Ended
	Sep. 30, 2023 USD ($)
Derivative [Line Items]
Notional Amount	$ 1,900
Fair Value Gain (Loss)	(351)
Southern Company parent | Fair Value Hedges of Existing Debt | March 2028
Derivative [Line Items]
Notional Amount	$ 400
Interest Rate Received	1.75%
Fair Value Gain (Loss)	$ (56)
Southern Company parent | Fair Value Hedges of Existing Debt | April 2030
Derivative [Line Items]
Notional Amount	$ 1,000
Interest Rate Received	3.70%
Fair Value Gain (Loss)	$ (196)
SOUTHERN Co GAS | Fair Value Hedges of Existing Debt
Derivative [Line Items]
Fair Value Gain (Loss)	(99)
SOUTHERN Co GAS | Fair Value Hedges of Existing Debt | January 2031
Derivative [Line Items]
Notional Amount	$ 500
Interest Rate Received	1.75%
Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate | Southern Company parent | Fair Value Hedges of Existing Debt | March 2028
Derivative [Line Items]
Weighted Average Interest Rate Paid	0.80%
Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate | Southern Company parent | Fair Value Hedges of Existing Debt | April 2030
Derivative [Line Items]
Weighted Average Interest Rate Paid	2.48%
Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate | SOUTHERN Co GAS | Fair Value Hedges of Existing Debt | January 2031
Derivative [Line Items]
Weighted Average Interest Rate Paid	0.49%

Derivatives - Schedule of Forei

Derivatives - Schedule of Foreign Currency Derivatives (Details) - 9 months ended Sep. 30, 2023 - Foreign currency derivatives € in Millions, $ in Millions	USD ($)	EUR (€)
Derivative [Line Items]
Pay Notional	$ 2,040
Receive Notional | €		€ 1,750
Fair Value Gain (Loss)	(192)
Cash Flow Hedges of Forecasted Debt | SOUTHERN POWER CO
Derivative [Line Items]
Pay Notional	$ 564
Pay Rate	3.78%
Receive Notional | €		500
Receive Rate	1.85%
Fair Value Gain (Loss)	$ (42)
Fair Value Hedges of Existing Debt | Southern Company parent
Derivative [Line Items]
Pay Notional	$ 1,476
Pay Rate	3.39%
Receive Notional | €		€ 1,250
Receive Rate	1.88%
Fair Value Gain (Loss)	$ (150)

Derivatives - Schedule of Deriv

Derivatives - Schedule of Derivative Category and Balance Sheet Location (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	$ 80	$ 211
Derivative asset, Gross amounts offset	(37)	(70)
Derivative asset, net amounts recognized in the balance sheets	43	141
Derivative liability, gross amount recognized	794	728
Derivative liability, Gross amounts offset	(86)	(111)
Derivative liability, net amounts recognized in the balance sheets	708	617
Collateral already posted, assets, aggregate fair value	49
Interest rate derivatives
Derivatives, Fair Value [Line Items]
Derivative liability, net amounts recognized in the balance sheets	78
Energy-related derivatives not designated as hedging instruments
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	6	15
Derivative liability, gross amount recognized	10	14
Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Assets from risk management activities
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	5	13
Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Liabilities from risk management activities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	8	13
Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Other deferred charges and assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	1	2
Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Other deferred credits and liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	2	1
Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	70	175
Derivative liability, gross amount recognized	211	165
Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Assets from risk management activities
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	34	123
Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Liabilities from risk management activities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	134	121
Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred charges and assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	36	52
Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred credits and liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	77	44
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	4	21
Derivative liability, gross amount recognized	573	549
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Assets from risk management activities
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	0	3
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Liabilities from risk management activities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	28	27
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred charges and assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	4	6
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred credits and liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	2	4
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Interest rate derivatives | Assets from risk management activities
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	0	12
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Interest rate derivatives | Liabilities from risk management activities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	80	62
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Interest rate derivatives | Other deferred charges and assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	0	0
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Interest rate derivatives | Other deferred credits and liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	271	240
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Foreign currency derivatives | Assets from risk management activities
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	0	0
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Foreign currency derivatives | Liabilities from risk management activities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	35	34
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Foreign currency derivatives | Other deferred charges and assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	0	0
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Foreign currency derivatives | Other deferred credits and liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	157	182
ALABAMA POWER CO
Derivatives, Fair Value [Line Items]
Derivative asset, Gross amounts offset	(17)	(24)
Derivative asset, net amounts recognized in the balance sheets	9	38
Derivative liability, Gross amounts offset	(17)	(24)
Derivative liability, net amounts recognized in the balance sheets	58	15
Collateral already posted, assets, aggregate fair value	0
ALABAMA POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	26	62
Derivative liability, gross amount recognized	75	39
ALABAMA POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other current assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	15	42
ALABAMA POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	46	21
ALABAMA POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred charges and assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	11	20
ALABAMA POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred credits and liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	29	18
GEORGIA POWER CO
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	14	42
Derivative asset, Gross amounts offset	(11)	(21)
Derivative asset, net amounts recognized in the balance sheets	3	21
Derivative liability, gross amount recognized	83	62
Derivative liability, Gross amounts offset	(11)	(21)
Derivative liability, net amounts recognized in the balance sheets	72	41
GEORGIA POWER CO | Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Other current assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	0	0
GEORGIA POWER CO | Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	0	1
GEORGIA POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	14	42
Derivative liability, gross amount recognized	83	61
GEORGIA POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Assets from risk management activities
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	4	36
GEORGIA POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	57	43
GEORGIA POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred charges and assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	10	6
GEORGIA POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred credits and liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	26	18
MISSISSIPPI POWER CO
Derivatives, Fair Value [Line Items]
Derivative asset, Gross amounts offset	(17)	(17)
Derivative asset, net amounts recognized in the balance sheets	7	42
Derivative liability, Gross amounts offset	(17)	(17)
Derivative liability, net amounts recognized in the balance sheets	27	15
MISSISSIPPI POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	24	59
Derivative liability, gross amount recognized	44	32
MISSISSIPPI POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Assets from risk management activities
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	9	33
MISSISSIPPI POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	22	24
MISSISSIPPI POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred charges and assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	15	26
MISSISSIPPI POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred credits and liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	22	8
SOUTHERN POWER CO
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	5	8
Derivative asset, Gross amounts offset	(1)	0
Derivative asset, net amounts recognized in the balance sheets	4	8
Derivative liability, gross amount recognized	48	59
Derivative liability, Gross amounts offset	(1)	0
Derivative liability, net amounts recognized in the balance sheets	47	59
Collateral already posted, assets, aggregate fair value	18
SOUTHERN POWER CO | Interest rate derivatives
Derivatives, Fair Value [Line Items]
Derivative liability, net amounts recognized in the balance sheets	20
SOUTHERN POWER CO | Energy-related derivatives not designated as hedging instruments
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	1	3
Derivative liability, gross amount recognized	1	0
SOUTHERN POWER CO | Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Other current assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	1	2
SOUTHERN POWER CO | Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	1	0
SOUTHERN POWER CO | Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Other deferred charges and assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	0	1
SOUTHERN POWER CO | Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Other deferred credits and liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	0	0
SOUTHERN POWER CO | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	4	5
Derivative liability, gross amount recognized	47	59
SOUTHERN POWER CO | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other current assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	0	0
SOUTHERN POWER CO | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	5	12
SOUTHERN POWER CO | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred charges and assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	4	5
SOUTHERN POWER CO | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred credits and liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	0	0
SOUTHERN POWER CO | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Foreign currency derivatives | Other current assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	0	0
SOUTHERN POWER CO | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Foreign currency derivatives | Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	11	11
SOUTHERN POWER CO | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Foreign currency derivatives | Other deferred charges and assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	0	0
SOUTHERN POWER CO | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Foreign currency derivatives | Other deferred credits and liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	31	36
SOUTHERN Co GAS
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	11	28
Derivative asset, Gross amounts offset	9	0
Derivative asset, net amounts recognized in the balance sheets	20	28
Derivative liability, gross amount recognized	142	151
Derivative liability, Gross amounts offset	(40)	(41)
Derivative liability, net amounts recognized in the balance sheets	102	110
Collateral already posted, assets, aggregate fair value	49	41
SOUTHERN Co GAS | Energy-related derivatives not designated as hedging instruments
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	5	12
Derivative liability, gross amount recognized	9	13
SOUTHERN Co GAS | Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Other current assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	4	11
SOUTHERN Co GAS | Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	7	12
SOUTHERN Co GAS | Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Other deferred charges and assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	1	1
SOUTHERN Co GAS | Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Other deferred credits and liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	2	1
SOUTHERN Co GAS | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other current assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	6	12
SOUTHERN Co GAS | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	9	33
SOUTHERN Co GAS | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	0	4
Derivative liability, gross amount recognized	124	105
SOUTHERN Co GAS | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other current assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	0	3
SOUTHERN Co GAS | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	23	15
SOUTHERN Co GAS | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred charges and assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	0	1
SOUTHERN Co GAS | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred credits and liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	2	4
SOUTHERN Co GAS | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Interest rate derivatives | Other current assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	0	0
SOUTHERN Co GAS | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Interest rate derivatives | Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	21	14
SOUTHERN Co GAS | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Interest rate derivatives | Other deferred charges and assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross amount recognized	0	0
SOUTHERN Co GAS | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Interest rate derivatives | Other deferred credits and liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross amount recognized	$ 78	$ 72

Derivatives - Schedule of Pre-t

Derivatives - Schedule of Pre-tax Effects of Unrealized Derivative Gains (Losses) (Details) - Energy-related derivatives - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	$ (132)	$ 9
Other regulatory assets, current
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	(113)	(71)
Other regulatory assets, deferred
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	(48)	(23)
Other regulatory liabilities, current
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	23	72
Other regulatory liabilities, deferred
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	6	31
ALABAMA POWER CO
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	(49)	23
ALABAMA POWER CO | Other regulatory assets, current
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	(39)	(8)
ALABAMA POWER CO | Other regulatory assets, deferred
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	(19)	(7)
ALABAMA POWER CO | Other regulatory liabilities, current
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	8	29
ALABAMA POWER CO | Other regulatory liabilities, deferred
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	1	9
GEORGIA POWER CO
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	(69)	(19)
GEORGIA POWER CO | Other regulatory assets, current
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	(54)	(26)
GEORGIA POWER CO | Other regulatory assets, deferred
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	(18)	(14)
GEORGIA POWER CO | Other regulatory liabilities, current
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	1	19
GEORGIA POWER CO | Other regulatory liabilities, deferred
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	2	2
MISSISSIPPI POWER CO
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	(20)	27
MISSISSIPPI POWER CO | Other regulatory assets, current
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	(16)	(13)
MISSISSIPPI POWER CO | Other regulatory assets, deferred
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	(11)	(2)
MISSISSIPPI POWER CO | Other regulatory liabilities, current
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	4	22
MISSISSIPPI POWER CO | Other regulatory liabilities, deferred
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	3	20
SOUTHERN Co GAS
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	6	(22)
SOUTHERN Co GAS | Other regulatory assets, current
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	(4)	(24)
SOUTHERN Co GAS | Other regulatory assets, deferred
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	0	0
SOUTHERN Co GAS | Other regulatory liabilities, current
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	10	2
SOUTHERN Co GAS | Other regulatory liabilities, deferred
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)	$ 0	$ 0

Derivatives - Schedule of Pre_2

Derivatives - Schedule of Pre-Tax Effects of Hedging on AOCI (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	$ 5	$ 2	$ (45)	$ (32)
Cash Flow Hedging | Energy-related derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	(4)	11	(55)	51
Cash Flow Hedging | Interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	(3)	6	(12)	36
Cash Flow Hedging | Foreign currency derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	(15)	(35)	(6)	(137)
Fair Value Hedging | Foreign currency derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	27	20	28	18
GEORGIA POWER CO | Cash Flow Hedging | Interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	0	0	(3)	31
SOUTHERN POWER CO
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	(15)	(46)	(20)	(141)
SOUTHERN POWER CO | Cash Flow Hedging | Energy-related derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	0	(11)	(14)	(4)
SOUTHERN POWER CO | Cash Flow Hedging | Foreign currency derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	(15)	(35)	(6)	(137)
SOUTHERN Co GAS
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	(8)	27	(41)	55
SOUTHERN Co GAS | Cash Flow Hedging | Energy-related derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	(4)	22	(41)	55
SOUTHERN Co GAS | Cash Flow Hedging | Interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	$ (4)	$ 5	$ 0	$ 0

Derivatives - Schedule of Pre_3

Derivatives - Schedule of Pre-Tax Effects of Cash Flow and Fair Value Hedging on Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Derivative [Line Items]
Depreciation and amortization	$ 1,143	$ 922	$ 3,365	$ 2,728
Total interest expense, net of amounts capitalized	(620)	(511)	(1,812)	(1,461)
Total other income (expense), net	141	132	428	414
Utilities Operating Expense, Maintenance and Operations	1,424	1,527	4,352	4,568
Natural gas
Derivative [Line Items]
Total cost of sales	102	294	1,199	1,840
Other Income (Expense)
Derivative [Line Items]
Amount excluded from effectiveness testing recognized in earnings	(27)	(21)	(28)	(17)
Cash Flow Hedging | Energy-related derivatives | Cost of Sales
Derivative [Line Items]
Gain (loss) on hedges	(4)	9	(32)	28
Cash Flow Hedging | Energy-related derivatives | Depreciation and Amortization
Derivative [Line Items]
Gain (loss) on hedges	(5)	(1)	(18)	5
Cash Flow Hedging | Energy-related derivatives | Operating Expense
Derivative [Line Items]
Gain (loss) on hedges	(1)	0	(2)	0
Cash Flow Hedging | Interest rate derivatives | Interest Expense
Derivative [Line Items]
Gain (loss) on hedges	(22)	(7)	(31)	(19)
Cash Flow Hedging | Foreign currency derivatives | Interest Expense
Derivative [Line Items]
Gain (loss) on hedges	(3)	(3)	(8)	(16)
Cash Flow Hedging | Foreign currency derivatives | Other Income (Expense)
Derivative [Line Items]
Gain (loss) on hedges	(14)	(32)	(4)	(129)
Fair Value Hedging | Interest rate derivatives | Interest Expense
Derivative [Line Items]
Gain (loss) on hedges	(47)	(102)	(50)	(300)
Fair Value Hedging | Foreign currency derivatives | Other Income (Expense)
Derivative [Line Items]
Gain (loss) on hedges	(7)	(59)	19	(180)
SOUTHERN POWER CO
Derivative [Line Items]
Depreciation and amortization	130	133	380	384
Total interest expense, net of amounts capitalized	(32)	(32)	(98)	(105)
Total other income (expense), net	4	3	8	5
Utilities Operating Expense, Maintenance and Operations	104	113	327	332
SOUTHERN POWER CO | Cash Flow Hedging | Energy-related derivatives | Depreciation and Amortization
Derivative [Line Items]
Gain (loss) on hedges	(5)	(1)	(18)	5
SOUTHERN POWER CO | Cash Flow Hedging | Foreign currency derivatives | Interest Expense
Derivative [Line Items]
Gain (loss) on hedges	(3)	(3)	(8)	(16)
SOUTHERN POWER CO | Cash Flow Hedging | Foreign currency derivatives | Other Income (Expense)
Derivative [Line Items]
Gain (loss) on hedges	(14)	(32)	(4)	(129)
SOUTHERN Co GAS
Derivative [Line Items]
Depreciation and amortization	145	140	429	414
Total interest expense, net of amounts capitalized	(77)	(65)	(226)	(187)
Total other income (expense), net	19	15	50	47
Utilities Operating Expense, Maintenance and Operations	264	252	879	824
SOUTHERN Co GAS | Natural gas
Derivative [Line Items]
Total cost of sales	102	294	1,199	1,840
SOUTHERN Co GAS | Cash Flow Hedging | Energy-related derivatives | Cost of Sales
Derivative [Line Items]
Gain (loss) on hedges	(4)	9	(32)	28
SOUTHERN Co GAS | Cash Flow Hedging | Energy-related derivatives | Operating Expense
Derivative [Line Items]
Gain (loss) on hedges	(1)	0	(2)	0
SOUTHERN Co GAS | Cash Flow Hedging | Interest rate derivatives | Interest Expense
Derivative [Line Items]
Gain (loss) on hedges	(18)	(2)	(18)	(3)
SOUTHERN Co GAS | Fair Value Hedging | Interest rate derivatives | Interest Expense
Derivative [Line Items]
Gain (loss) on hedges	(11)	(30)	(14)	(87)
Traditional Electric Operating Companies | Cash Flow Hedging | Interest rate derivatives | Interest Expense
Derivative [Line Items]
Gain (loss) on hedges	0	0	0	0
Traditional Electric Operating Companies | Fair Value Hedging | Interest rate derivatives | Interest Expense
Derivative [Line Items]
Gain (loss) on hedges	$ 0	$ 0	$ 0	$ 0

Derivatives - Schedule of Cumul

Derivatives - Schedule of Cumulative Basis Adjustments for Fair Value Hedges (Details) - Fair Value Hedging - Long-term debt - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Derivative [Line Items]
Carrying Amount of the Hedged Item	$ (2,873)	$ (2,927)
Cumulative Amount of Fair Value Hedging Adjustment included in Carrying Amount of the Hedged Item	328	282
SOUTHERN Co GAS
Derivative [Line Items]
Carrying Amount of the Hedged Item	(402)	(415)
Cumulative Amount of Fair Value Hedging Adjustment included in Carrying Amount of the Hedged Item	$ 95	$ 81

Derivatives - Schedule of Pre_4

Derivatives - Schedule of Pre-tax Effect of Interest Rate and Energy Related Derivatives on Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Weather Derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	$ 0	$ 0	$ 14	$ 0
Energy-related derivatives not designated as hedging instruments | Energy-related derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	7	1	36	(17)
Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Natural gas revenues
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	0	3	0	(10)
Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Cost of natural gas
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	$ 7	$ (2)	$ 36	$ (7)

Acquisitions and Dispositions -

Acquisitions and Dispositions - Southern Power (Details) - SOUTHERN POWER CO $ in Millions	9 Months Ended
	Sep. 30, 2023 USD ($) MW
Millers Branch Solar Development
Business Acquisition [Line Items]
Approximate nameplate capacity	200
Ownership percentage by parent	100%
Life output of plant (in years)	20 years
South Cheyenne Solar Facility
Business Acquisition [Line Items]
Approximate nameplate capacity	150
Ownership percentage by parent	10,000%
Life output of plant (in years)	20 years
South Cheyenne Solar Facility and Millers Branch Solar Development
Business Acquisition [Line Items]
Payments to Acquire Businesses and Interest in Affiliates | $	$ 193
Maximum | Millers Branch Solar Development
Business Acquisition [Line Items]
Approximate nameplate capacity	300

Acquisitions and Dispositions_2

Acquisitions and Dispositions - Southern Company Gas (Details) $ in Millions	Sep. 22, 2023 USD ($)
Disposal Group, Disposed of by Sale | California Natural Gas | Natural Gas Storage Facility | SOUTHERN Co GAS
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Immaterial loss on sale	$ 0

Segment and Related Informati_3

Segment and Related Information - Narrative (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($) state	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) state segment	Sep. 30, 2022 USD ($)
Segment Reporting Information [Line Items]
Number of states in which entity operates | state	3		3
Operating revenues	$ 7,107	$ 7,116	$ 18,886	$ 19,599
SOUTHERN POWER CO
Segment Reporting Information [Line Items]
Operating revenues	$ 480	1,010	$ 1,248	2,157
SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Number of states in which entity operates | state	4		4
Operating revenues	$ 674	843	$ 3,338	3,948
Number of reportable segments | segment			3
SOUTHERN Co GAS | Southern Natural Gas Company, LLC
Segment Reporting Information [Line Items]
Ownership percentage, equity method investment	50%		50%
SOUTHERN Co GAS | Dalton Pipeline
Segment Reporting Information [Line Items]
Ownership percentage, equity method investment	50%		50%
Traditional Electric Operating Companies | Wholesale revenues, affiliates | SOUTHERN POWER CO
Segment Reporting Information [Line Items]
Operating revenues	$ 156	336	$ 406	673
Traditional Electric Operating Companies | Natural Gas | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	$ 0	$ 0	$ 0	$ 0

Segment and Related Informati_4

Segment and Related Information - Schedule of Financial Data for Business Segments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Segment Reporting Information [Line Items]
Operating revenues	$ 6,980	$ 8,378	$ 19,208	$ 22,232
Net income	1,422	1,472	3,121	3,611
Goodwill	5,161		5,161		$ 5,161
Total assets	138,321		138,321		134,891
Amount awarded			18
SOUTHERN POWER CO
Segment Reporting Information [Line Items]
Operating revenues	653	1,180	1,686	2,618
Net income	100	95	288	265
Total assets	13,090		13,090		13,081
Amount awarded	18
After tax amount awarded	9		9
SOUTHERN POWER CO | Disposal Group, Disposed of by Sale | Spare Parts
Segment Reporting Information [Line Items]
Gain (loss) on sale			16
Gain (loss) on sale, after tax			12
SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	689	857	3,417	3,998
Net income	82	83	475	516
Goodwill	5,015		5,015		5,015
Total assets	24,823		24,823		24,621
GEORGIA POWER CO
Segment Reporting Information [Line Items]
Operating revenues	3,237	3,889	7,805	9,218
Total assets	56,149		56,149		53,163
GEORGIA POWER CO | Disposal Group, Disposed of by Sale | Spare Parts
Segment Reporting Information [Line Items]
Gain (loss) on sale		(70)		(18)
Gain (loss) on sale, after tax		(52)		(13)
Electric Utilities
Segment Reporting Information [Line Items]
Operating revenues	6,167	7,427	15,414	17,943
SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	689	857	3,417	3,998
Operating Segments | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	683	844	3,402	3,977
Net income	96	81	484	506
Total assets	25,686		25,686		25,233
Operating Segments | Electric Utilities
Segment Reporting Information [Line Items]
Operating revenues	6,167	7,427	15,414	17,943
Net income	1,519	1,540	3,140	3,521
Goodwill	2		2		2
Total assets	111,986		111,986		108,283
Operating Segments | Traditional Electric Operating Companies
Segment Reporting Information [Line Items]
Operating revenues	5,674	6,938	14,145	16,716
Net income	1,419	1,445	2,852	3,256
Goodwill	0		0		0
Total assets	99,464		99,464		95,861
Operating Segments | SOUTHERN POWER CO
Segment Reporting Information [Line Items]
Operating revenues	653	1,180	1,686	2,618
Net income	100	95	288	265
Goodwill	2		2		2
Total assets	13,090		13,090		13,081
Operating Segments | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	689	857	3,417	3,998
Net income	82	83	475	516
Goodwill	5,015		5,015		5,015
Total assets	24,823		24,823		24,621
Operating Segments | All Other
Segment Reporting Information [Line Items]
Operating revenues	154	135	499	418
Net income	(179)	(152)	(490)	(415)
Goodwill	144		144		144
Total assets	2,370		2,370		2,665
Operating Segments | All Other | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	8	16	30	43
Net income	(14)	2	(9)	10
Total assets	9,795		9,795		8,943
Eliminations
Segment Reporting Information [Line Items]
Operating revenues	(30)	(41)	(122)	(127)
Net income	0	1	(4)	(11)
Goodwill	0		0		0
Total assets	(858)		(858)		(678)
Eliminations | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	(2)	(3)	(15)	(22)
Net income	0	0	0	0
Total assets	(10,658)		(10,658)		(9,555)
Eliminations | Electric Utilities
Segment Reporting Information [Line Items]
Operating revenues	(160)	(691)	(417)	(1,391)
Net income	0	$ 0	0	$ 0
Goodwill	0		0		0
Total assets	$ (568)		$ (568)		$ (659)

Segment and Related Informati_5

Segment and Related Information - Schedule of Financial Data for Products and Services (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Concentration Risk [Line Items]
Operating revenues	$ 6,980	$ 8,378	$ 19,208	$ 22,232
Electric Utilities
Concentration Risk [Line Items]
Operating revenues	6,167	7,427	15,414	17,943
Southern Company Gas' Revenues
Concentration Risk [Line Items]
Operating revenues	689	857	3,417	3,998
Retail electric revenues
Concentration Risk [Line Items]
Operating revenues	5,139	5,961	12,597	14,363
Retail electric revenues | Electric Utilities
Concentration Risk [Line Items]
Operating revenues	5,139	5,961	12,597	14,363
Wholesale electric revenues
Concentration Risk [Line Items]
Operating revenues	727	1,197	1,930	2,798
Wholesale electric revenues | Electric Utilities
Concentration Risk [Line Items]
Operating revenues	727	1,197	1,930	2,798
Other Revenue | Electric Utilities
Concentration Risk [Line Items]
Operating revenues	301	269	887	782
Other electric revenues
Concentration Risk [Line Items]
Operating revenues	203	185	602	554
Natural Gas
Concentration Risk [Line Items]
Operating revenues	689	857	3,417	3,998
Gas Distribution Operations | Southern Company Gas' Revenues
Concentration Risk [Line Items]
Operating revenues	617	748	2,989	3,513
Gas marketing services | Southern Company Gas' Revenues
Concentration Risk [Line Items]
Operating revenues	56	85	376	420
Other | Southern Company Gas' Revenues
Concentration Risk [Line Items]
Operating revenues	16	24	52	65
Other revenues
Concentration Risk [Line Items]
Operating revenues	$ 222	$ 178	$ 662	$ 519

Segment and Related Informati_6

Segment and Related Information - Schedule of Business Segment Financial Data (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Segment Reporting Information [Line Items]
Total operating revenues	$ 6,980	$ 8,378	$ 19,208	$ 22,232
Net income after dividends on preferred stock	1,422	1,472	3,121	3,611
Total assets	138,321		138,321		$ 134,891
SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Total operating revenues	689	857	3,417	3,998
Net income after dividends on preferred stock	82	83	475	516
Total assets	24,823		24,823		24,621
SOUTHERN POWER CO
Segment Reporting Information [Line Items]
Total operating revenues	653	1,180	1,686	2,618
Net income after dividends on preferred stock	100	95	288	265
Total assets	13,090		13,090		13,081
Operating Segments | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Total operating revenues	683	844	3,402	3,977
Net income after dividends on preferred stock	96	81	484	506
Total assets	25,686		25,686		25,233
Operating Segments | Gas distribution operations | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Total operating revenues	619	751	3,002	3,533
Net income after dividends on preferred stock	70	59	352	365
Total assets	22,625		22,625		22,040
Operating Segments | Gas Pipeline Investments | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Total operating revenues	8	8	24	24
Net income after dividends on preferred stock	24	24	73	76
Total assets	1,542		1,542		1,577
Operating Segments | Gas marketing services | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Total operating revenues	56	85	376	420
Net income after dividends on preferred stock	2	(2)	59	65
Total assets	1,519		1,519		1,616
Operating Segments | All Other
Segment Reporting Information [Line Items]
Total operating revenues	154	135	499	418
Net income after dividends on preferred stock	(179)	(152)	(490)	(415)
Total assets	2,370		2,370		2,665
Operating Segments | All Other | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Total operating revenues	8	16	30	43
Net income after dividends on preferred stock	(14)	2	(9)	10
Total assets	9,795		9,795		8,943
Eliminations
Segment Reporting Information [Line Items]
Total operating revenues	(30)	(41)	(122)	(127)
Net income after dividends on preferred stock	0	1	(4)	(11)
Total assets	(858)		(858)		(678)
Eliminations | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Total operating revenues	(2)	(3)	(15)	(22)
Net income after dividends on preferred stock	0	$ 0	0	$ 0
Total assets	$ (10,658)		$ (10,658)		$ (9,555)