Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Operating Activities:
Net income	$ 2,592	$ 2,746
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	2,944	2,903
Deferred income taxes	89	(196)
Utilization of federal investment tax credits	256	319
Allowance for equity funds used during construction	(140)	(106)
Pension, postretirement, and other employee benefits	(218)	(190)
Settlement of asset retirement obligations	(341)	(315)
Stock based compensation expense	134	99
Estimated loss on Plant Vogtle Units 3 and 4	772	149
Storm damage accruals	166	171
Impairment charges	91	154
(Gain) loss on dispositions, net	(171)	(36)
Retail fuel cost under recovery – long-term	(209)	0
Other, net	(7)	(14)
Changes in certain current assets and liabilities —
-Receivables	2	125
-Materials and supplies	(91)	(141)
-Natural gas cost under recovery	(432)	0
-Other current assets	(160)	(119)
-Accounts payable	(45)	(428)
-Accrued taxes	288	289
-Accrued compensation	(93)	(183)
-Accrued interest	(110)	(52)
-Retail fuel cost over recovery	(150)	158
-Customer refunds	(58)	(226)
-Other current liabilities	(168)	7
Net cash provided from operating activities	5,081	5,220
Investing Activities:
Business acquisitions, net of cash acquired	(345)	(81)
Property additions	(5,222)	(5,365)
Nuclear decommissioning trust fund purchases	(1,301)	(714)
Nuclear decommissioning trust fund sales	1,297	708
Proceeds from dispositions	160	987
Cost of removal, net of salvage	(282)	(233)
Payments pursuant to LTSAs	(145)	(139)
Other investing activities	(12)	(55)
Net cash used for investing activities	(5,850)	(4,892)
Financing Activities:
Decrease in notes payable	(203)	(1,534)
Proceeds —
Long-term debt	6,793	7,543
Common stock	62	63
Short-term borrowings	325	615
Redemptions and repurchases —
Long-term debt	(3,060)	(2,472)
Short-term borrowings	(25)	(840)
Capital contributions from noncontrolling interests	415	173
Distributions to noncontrolling interests	(204)	(164)
Payment of common stock dividends	(2,077)	(2,008)
Other financing activities	(224)	(299)
Net cash provided from financing activities	1,802	1,077
Net Change in Cash, Cash Equivalents, and Restricted Cash	1,033	1,405
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	1,068	1,978
Cash, Cash Equivalents, and Restricted Cash at End of Period	2,101	3,383
Cash paid during the period for —
Interest, net of amounts capitalized	1,417	1,346
Income taxes, net	92	66
Noncash transactions —
Accrued property additions at end of period	915	917
Contributions from noncontrolling interests	89	9
Contributions of wind turbine equipment	82	17
Right-of-use assets obtained under finance leases	92	166
ALABAMA POWER CO
Operating Activities:
Net income	1,200	1,033
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	748	731
Deferred income taxes	104	71
Allowance for equity funds used during construction	(38)	(34)
Pension, postretirement, and other employee benefits	(74)	(71)
Settlement of asset retirement obligations	(152)	(157)
Other, net	(51)	33
Changes in certain current assets and liabilities —
-Receivables	(128)	(130)
-Fossil fuel stock	91	4
-Prepayments	(24)	(32)
-Materials and supplies	(13)	(55)
-Retail fuel cost under recovery	(79)	0
-Other current assets	(19)	(35)
-Accounts payable	(230)	(248)
-Accrued taxes	178	142
-Accrued compensation	(37)	(55)
-Retail fuel cost over recovery	(18)	74
-Other current liabilities	(77)	(76)
Net cash provided from operating activities	1,419	1,229
Investing Activities:
Property additions	(1,235)	(1,460)
Nuclear decommissioning trust fund purchases	(536)	(213)
Nuclear decommissioning trust fund sales	536	213
Cost of removal, net of salvage	(93)	(68)
Change in construction payables, net	12	(46)
Other investing activities	(19)	(17)
Net cash used for investing activities	(1,335)	(1,591)
Proceeds —
Senior notes	600	600
Pollution control revenue bonds	0	87
Redemptions and repurchases —
Pollution control revenue bonds	0	(87)
Other long-term debt	(206)	0
Senior notes	(200)	0
Capital contributions from parent company	630	649
Payment of common stock dividends	(738)	(718)
Other financing activities	(30)	(26)
Net cash provided from financing activities	56	505
Net Change in Cash, Cash Equivalents, and Restricted Cash	140	143
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	530	894
Cash, Cash Equivalents, and Restricted Cash at End of Period	670	1,037
Cash paid during the period for —
Interest, net of amounts capitalized	246	249
Income taxes, net	183	203
Noncash transactions —
Accrued property additions at end of period	178	154
Right-of-use assets obtained under leases	2	65
GEORGIA POWER CO
Operating Activities:
Net income	1,030	1,411
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	1,164	1,206
Deferred income taxes	(299)	(167)
Allowance for equity funds used during construction	(94)	(63)
Pension, postretirement, and other employee benefits	(112)	(98)
Settlement of asset retirement obligations	(154)	(130)
Estimated loss on Plant Vogtle Units 3 and 4	772	149
Storm damage accruals	160	160
Retail fuel cost under recovery – long-term	(203)	0
Other, net	88	11
Changes in certain current assets and liabilities —
-Receivables	(85)	(168)
-Fossil fuel stock	77	4
-Materials and supplies	(60)	(74)
-Other current assets	(51)	(69)
-Accounts payable	164	25
-Accrued taxes	154	44
-Retail fuel cost over recovery	(113)	84
-Customer refunds	(5)	(162)
-Other current liabilities	(83)	(38)
Net cash provided from operating activities	2,350	2,125
Investing Activities:
Property additions	(2,411)	(2,519)
Nuclear decommissioning trust fund purchases	(766)	(500)
Nuclear decommissioning trust fund sales	761	495
Proceeds from dispositions	4	143
Cost of removal, net of salvage	(99)	(93)
Change in construction payables, net	(68)	(14)
Payments pursuant to LTSAs	(38)	(44)
Contributions in aid of construction	71	18
Other investing activities	(26)	(12)
Net cash used for investing activities	(2,572)	(2,526)
Financing Activities:
Decrease in notes payable	(60)	(115)
Proceeds —
Senior notes	750	1,500
Pollution control revenue bonds	122	53
FFB loan	371	519
Short-term borrowings	0	250
Redemptions and repurchases —
Short-term borrowings	0	(375)
Pollution control revenue bonds	(69)	(148)
Senior notes	(325)	(950)
FFB loan	(75)	(55)
Capital contributions from parent company	1,054	1,379
Payment of common stock dividends	(1,237)	(1,156)
Other financing activities	(26)	(35)
Net cash provided from financing activities	505	867
Net Change in Cash, Cash Equivalents, and Restricted Cash	283	466
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	9	52
Cash, Cash Equivalents, and Restricted Cash at End of Period	292	518
Cash paid during the period for —
Interest, net of amounts capitalized	325	316
Income taxes, net	237	311
Noncash transactions —
Accrued property additions at end of period	477	523
Right-of-use assets obtained under operating leases	3	30
MISSISSIPPI POWER CO
Operating Activities:
Net income	133	138
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	161	142
Settlement of asset retirement obligations	(18)	(16)
Other, net	(20)	(11)
Changes in certain current assets and liabilities —
-Receivables	(19)	(3)
-Other current assets	(9)	(7)
-Accounts payable	(12)	(54)
-Accrued taxes	(20)	15
-Retail fuel cost over recovery	(19)	0
-Other current liabilities	(18)	(18)
Net cash provided from operating activities	159	186
Investing Activities:
Property additions	(135)	(174)
Change in construction payables, net	(11)	7
Payments pursuant to LTSAs	(21)	(20)
Other investing activities	(15)	(13)
Net cash used for investing activities	(182)	(200)
Financing Activities:
Decrease in notes payable	(25)	0
Proceeds —
Senior notes	525	0
Pollution control revenue bonds	0	34
Short-term borrowings	0	40
Other long-term debt	0	100
Redemptions and repurchases —
Short-term borrowings	0	(40)
Pollution control revenue bonds	0	(41)
Other revenue bonds	(270)	0
Other long-term debt	(75)	0
Senior notes	0	(275)
Capital contributions from parent company	103	80
Return of capital to parent company	0	(74)
Payment of common stock dividends	(118)	(37)
Other financing activities	(10)	(1)
Net cash provided from financing activities	130	(214)
Net Change in Cash, Cash Equivalents, and Restricted Cash	107	(228)
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	39	286
Cash, Cash Equivalents, and Restricted Cash at End of Period	146	58
Cash paid during the period for —
Interest, net of amounts capitalized	53	49
Income taxes, net	11	9
Noncash transactions —
Accrued property additions at end of period	23	42
SOUTHERN POWER CO
Operating Activities:
Net income	184	215
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	402	386
Deferred income taxes	(16)	(59)
Utilization of federal investment tax credits	237	318
Amortization of investment tax credits	(44)	(44)
(Gain) loss on dispositions, net	(39)	(39)
Other, net	14	(16)
Changes in certain current assets and liabilities —
-Receivables	(117)	(28)
-Prepaid income taxes	63	74
-Other current assets	(5)	(17)
-Accounts payable	55	(12)
-Accrued taxes	15	21
-Other current liabilities	1	(25)
Net cash provided from operating activities	750	774
Investing Activities:
Business acquisitions, net of cash acquired	(345)	(81)
Property additions	(355)	(135)
Proceeds from dispositions	22	663
Change in construction payables, net	(22)	(12)
Payments pursuant to LTSAs	(61)	(61)
Other investing activities	8	50
Net cash used for investing activities	(753)	424
Financing Activities:
Decrease in notes payable	(148)	(449)
Proceeds —
Senior notes	400	0
Redemptions and repurchases —
Short-term borrowings	0	(100)
Senior notes	0	(300)
Return of capital to parent company	(271)	0
Capital contributions from noncontrolling interests	415	173
Distributions to noncontrolling interests	(204)	(164)
Purchase of membership interests from noncontrolling interests	0	(60)
Payment of common stock dividends	(153)	(151)
Other financing activities	(6)	(9)
Net cash provided from financing activities	33	(1,060)
Net Change in Cash, Cash Equivalents, and Restricted Cash	30	138
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	183	279
Cash, Cash Equivalents, and Restricted Cash at End of Period	213	417
Cash paid during the period for —
Interest, net of amounts capitalized	118	123
Income taxes, net	(235)	(278)
Noncash transactions —
Accrued property additions at end of period	53	44
Contributions from noncontrolling interests	89	9
Contributions of wind turbine equipment	82	17
Right-of-use assets obtained under operating leases	66	30
SOUTHERN Co GAS
Operating Activities:
Net income	389	360
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	396	368
Deferred income taxes	289	(1)
Mark-to-market adjustments	147	104
Impairment of PennEast Pipeline investment	84	0
(Gain) loss on dispositions, net	(127)	2
Natural gas cost under recovery – long-term	(79)	0
Other, net	32	(21)
Changes in certain current assets and liabilities —
-Receivables	311	403
-Prepaid income taxes	(148)	(19)
-Natural gas cost under recovery	(432)	0
-Other current assets	(78)	(1)
-Accounts payable	30	(75)
-Other current liabilities	(57)	2
Net cash provided from operating activities	757	1,122
Investing Activities:
Property additions	(1,045)	(1,045)
Proceeds from dispositions	126	178
Cost of removal, net of salvage	(74)	(60)
Investment in unconsolidated subsidiaries	(3)	(79)
Other investing activities	30	33
Net cash used for investing activities	(966)	(973)
Financing Activities:
Increase in notes payable	38
Decrease in notes payable		(500)
Proceeds —
Senior notes	450	500
Short-term borrowings	300	0
First mortgage bonds	100	150
Redemptions and repurchases —
Senior notes	(300)	0
Medium-term notes	(30)	0
Capital contributions from parent company	63	215
Payment of common stock dividends	(397)	(399)
Other financing activities	(2)	(3)
Net cash provided from financing activities	222	(37)
Net Change in Cash, Cash Equivalents, and Restricted Cash	13	112
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	19	49
Cash, Cash Equivalents, and Restricted Cash at End of Period	32	161
Cash paid during the period for —
Interest, net of amounts capitalized	173	162
Income taxes, net	85	45
Noncash transactions —
Accrued property additions at end of period	$ 146	$ 146