Condensed Consolidated Statements of Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Operating Revenues:
Operating revenues	$ 6,238	$ 5,620	$ 17,346	$ 15,258
Operating Expenses:
Other operations and maintenance	1,446	1,286	4,257	3,785
Depreciation and amortization	896	889	2,658	2,619
Taxes other than income taxes	312	304	969	932
Estimated loss on Plant Vogtle Units 3 and 4	264	0	772	149
(Gain) loss on dispositions, net	(125)	0	(179)	(39)
Total operating expenses	4,515	3,785	13,317	11,102
Operating Income	1,723	1,835	4,029	4,156
Other Income and (Expense):
Allowance for equity funds used during construction	49	38	140	106
Earnings from equity method investments	30	33	35	105
Interest expense, net of amounts capitalized	(451)	(443)	(1,352)	(1,343)
Impairment of leveraged leases	0	0	(7)	(154)
Other income (expense), net	131	113	297	319
Total other income and (expense)	(241)	(259)	(887)	(967)
Earnings Before Income Taxes	1,482	1,576	3,142	3,189
Income taxes (benefit)	372	293	550	443
Consolidated Net Income	1,110	1,283	2,592	2,746
Dividends on preferred stock of subsidiaries	4	4	11	11
Net income (loss) attributable to noncontrolling interests	5	28	(27)	3
Net Income	$ 1,101	$ 1,251	$ 2,608	$ 2,732
Earnings per share -
Basic (in dollars per share)	$ 1.04	$ 1.18	$ 2.46	$ 2.58
Diluted (in dollars per share)	$ 1.03	$ 1.18	$ 2.44	$ 2.57
Average number of shares of common stock outstanding (in millions)
Basic (in shares)	1,061	1,058	1,060	1,058
Diluted (in shares)	1,068	1,064	1,067	1,064
Retail electric revenues
Operating Revenues:
Operating revenues	$ 4,551	$ 4,243	$ 11,492	$ 10,503
Wholesale electric revenues
Operating Revenues:
Operating revenues	731	584	1,822	1,473
Other electric revenues
Operating Revenues:
Operating revenues	179	164	525	484
Natural gas
Operating Revenues:
Operating revenues	623	477	2,994	2,362
Operating Expenses:
Total cost of sales	129	71	943	654
Other
Operating Revenues:
Operating revenues	154	152	513	436
Operating Expenses:
Total cost of sales	71	72	255	201
Fuel
Operating Expenses:
Total cost of sales	1,234	933	2,930	2,190
Purchased power
Operating Expenses:
Total cost of sales	288	230	712	611
Alternative revenue programs
Operating Revenues:
Operating revenues	(1)	(1)	3	6
ALABAMA POWER CO
Operating Revenues:
Operating revenues	1,904	1,729	5,019	4,445
Operating Expenses:
Other operations and maintenance	401	387	1,175	1,078
Depreciation and amortization	214	205	640	606
Taxes other than income taxes	99	103	303	311
Total operating expenses	1,208	1,109	3,332	2,962
Operating Income	696	620	1,687	1,483
Other Income and (Expense):
Allowance for equity funds used during construction	14	12	38	34
Interest expense, net of amounts capitalized	(84)	(84)	(252)	(255)
Other income (expense), net	29	30	93	78
Total other income and (expense)	(41)	(42)	(121)	(143)
Earnings Before Income Taxes	655	578	1,566	1,340
Income taxes (benefit)	152	130	366	307
Consolidated Net Income	503	448	1,200	1,033
Dividends on preferred stock of subsidiaries	4	4	11	11
Net Income	499	444	1,189	1,022
ALABAMA POWER CO | Retail electric revenues
Operating Revenues:
Operating revenues	1,651	1,575	4,357	4,003
ALABAMA POWER CO | Wholesale electric revenues
Operating Revenues:
Operating revenues	107	73	285	184
ALABAMA POWER CO | Wholesale revenues, affiliates
Operating Revenues:
Operating revenues	53	11	109	36
ALABAMA POWER CO | Other
Operating Revenues:
Operating revenues	93	70	268	222
ALABAMA POWER CO | Fuel
Operating Expenses:
Total cost of sales	373	306	927	721
ALABAMA POWER CO | Purchased power
Operating Expenses:
Total cost of sales	76	64	173	153
ALABAMA POWER CO | Purchased power, affiliates
Operating Expenses:
Total cost of sales	45	44	114	93
GEORGIA POWER CO
Operating Revenues:
Operating revenues	2,856	2,617	7,050	6,371
Operating Expenses:
Other operations and maintenance	544	483	1,558	1,411
Depreciation and amortization	345	358	1,025	1,064
Taxes other than income taxes	130	123	365	344
Estimated loss on Plant Vogtle Units 3 and 4	264	0	772	149
Total operating expenses	2,176	1,620	5,842	4,596
Operating Income	680	997	1,208	1,775
Other Income and (Expense):
Allowance for equity funds used during construction	33	22	94	63
Interest expense, net of amounts capitalized	(106)	(106)	(315)	(322)
Other income (expense), net	42	32	124	93
Total other income and (expense)	(31)	(52)	(97)	(166)
Earnings Before Income Taxes	649	945	1,111	1,609
Income taxes (benefit)	113	172	81	198
Consolidated Net Income	536	773	1,030	1,411
GEORGIA POWER CO | Retail electric revenues
Operating Revenues:
Operating revenues	2,652	2,435	6,465	5,870
GEORGIA POWER CO | Wholesale electric revenues
Operating Revenues:
Operating revenues	63	34	143	85
GEORGIA POWER CO | Other
Operating Revenues:
Operating revenues	141	148	442	416
GEORGIA POWER CO | Fuel
Operating Expenses:
Total cost of sales	432	368	1,088	826
GEORGIA POWER CO | Purchased power
Operating Expenses:
Total cost of sales	173	146	461	409
GEORGIA POWER CO | Purchased power, affiliates
Operating Expenses:
Total cost of sales	288	142	573	393
MISSISSIPPI POWER CO
Operating Revenues:
Operating revenues	378	336	988	895
Operating Expenses:
Other operations and maintenance	85	62	230	202
Depreciation and amortization	46	47	138	135
Taxes other than income taxes	33	31	96	90
Total operating expenses	309	249	815	711
Operating Income	69	87	173	184
Other Income and (Expense):
Interest expense, net of amounts capitalized	(16)	(14)	(45)	(45)
Other income (expense), net	7	6	27	19
Total other income and (expense)	(9)	(8)	(18)	(26)
Earnings Before Income Taxes	60	79	155	158
Income taxes (benefit)	10	12	22	20
Consolidated Net Income	50	67	133	138
MISSISSIPPI POWER CO | Retail electric revenues
Operating Revenues:
Operating revenues	248	232	670	630
MISSISSIPPI POWER CO | Wholesale electric revenues
Operating Revenues:
Operating revenues	60	61	178	164
MISSISSIPPI POWER CO | Wholesale revenues, affiliates
Operating Revenues:
Operating revenues	62	36	120	82
MISSISSIPPI POWER CO | Other
Operating Revenues:
Operating revenues	8	7	20	19
MISSISSIPPI POWER CO | Fuel
Operating Expenses:
Total cost of sales	139	103	330	266
MISSISSIPPI POWER CO | Purchased power
Operating Expenses:
Total cost of sales	6	6	21	18
SOUTHERN POWER CO
Operating Revenues:
Operating revenues	679	523	1,610	1,337
Operating Expenses:
Other operations and maintenance	94	89	308	245
Depreciation and amortization	132	129	383	367
Taxes other than income taxes	12	10	35	29
Loss on sales-type lease	15	0	15	0
(Gain) loss on dispositions, net	0	0	(39)	(39)
Total operating expenses	553	384	1,328	1,000
Operating Income	126	139	282	337
Other Income and (Expense):
Interest expense, net of amounts capitalized	(36)	(36)	(111)	(114)
Other income (expense), net	2	13	10	19
Total other income and (expense)	(34)	(23)	(101)	(95)
Earnings Before Income Taxes	92	116	181	242
Income taxes (benefit)	9	14	(3)	27
Consolidated Net Income	83	102	184	215
Net income (loss) attributable to noncontrolling interests	5	28	(27)	3
Net Income	78	74	211	212
SOUTHERN POWER CO | Wholesale electric revenues
Operating Revenues:
Operating revenues	503	418	1,231	1,047
SOUTHERN POWER CO | Wholesale revenues, affiliates
Operating Revenues:
Operating revenues	167	101	361	279
SOUTHERN POWER CO | Other
Operating Revenues:
Operating revenues	9	4	18	11
SOUTHERN POWER CO | Fuel
Operating Expenses:
Total cost of sales	259	137	540	346
SOUTHERN POWER CO | Purchased power
Operating Expenses:
Total cost of sales	41	19	86	52
SOUTHERN Co GAS
Operating Revenues:
Operating revenues	$ 623	$ 477	$ 2,994	$ 2,362
Operating Expenses:
Cost, Product and Service [Extensible Enumeration]	Natural gas	Natural gas	Natural gas	Natural gas
Other operations and maintenance	$ 238	$ 217	$ 776	$ 694
Depreciation and amortization	133	125	396	368
Taxes other than income taxes	36	35	166	154
(Gain) loss on dispositions, net	(121)	0	(127)	2
Total operating expenses	415	448	2,154	1,872
Operating Income	208	29	840	490
Other Income and (Expense):
Earnings from equity method investments	25	33	14	106
Interest expense, net of amounts capitalized	(57)	(57)	(175)	(171)
Other income (expense), net	13	12	(66)	33
Total other income and (expense)	(19)	(12)	(227)	(32)
Earnings Before Income Taxes	189	17	613	458
Income taxes (benefit)	133	3	224	98
Consolidated Net Income	56	14	389	360
SOUTHERN Co GAS | Natural gas
Operating Revenues:
Operating revenues	624	478	2,991	2,356
Operating Expenses:
Total cost of sales	129	71	943	654
SOUTHERN Co GAS | Alternative revenue programs
Operating Revenues:
Operating revenues	$ (1)	$ (1)	$ 3	$ 6