Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating Activities:
Net income	$ 1,107	$ 841
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	964	949
Deferred income taxes	140	(58)
Allowance for equity funds used during construction	(46)	(34)
Pension, postretirement, and other employee benefits	(78)	(67)
Settlement of asset retirement obligations	(109)	(86)
Stock based compensation expense	83	72
Estimated loss on Plant Vogtle Units 3 and 4	48	0
Storm damage accruals	54	56
(Gain) loss on dispositions, net	(41)	(38)
Natural gas cost under recovery – long-term	(185)	0
Other, net	114	55
Changes in certain current assets and liabilities —
-Receivables	308	317
-Prepayments	(98)	(110)
-Natural gas for sale, net of temporary LIFO liquidation	456	246
-Natural gas cost under recovery	(487)	0
-Other current assets	63	(67)
-Accounts payable	(216)	(504)
-Accrued taxes	(212)	(102)
-Accrued compensation	(417)	(473)
-Accrued interest	(90)	(60)
-Customer refunds	0	(103)
-Other current liabilities	(116)	60
Net cash provided from operating activities	1,242	894
Investing Activities:
Business acquisitions, net of cash acquired	(345)	0
Property additions	(1,678)	(1,560)
Nuclear decommissioning trust fund purchases	(550)	(254)
Nuclear decommissioning trust fund sales	546	249
Proceeds from dispositions	20	982
Cost of removal, net of salvage	(85)	(69)
Change in construction payables, net	(116)	(141)
Payments pursuant to LTSAs	(60)	(26)
Other investing activities	25	(70)
Net cash used for investing activities	(2,243)	(889)
Financing Activities:
Increase in notes payable, net	182
Decrease in notes payable, net		(685)
Proceeds —
Long-term debt	2,150	2,653
Common stock	14	52
Short-term borrowings	325	565
Redemptions and repurchases —
Long-term debt	(384)	(1,481)
Short-term borrowings	(25)	(100)
Capital contributions from noncontrolling interests	313	16
Distributions to noncontrolling interests	(46)	(48)
Payment of common stock dividends	(678)	(655)
Other financing activities	(117)	(132)
Net cash provided from financing activities	1,734	185
Net Change in Cash, Cash Equivalents, and Restricted Cash	733	190
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	1,068	1,978
Cash, Cash Equivalents, and Restricted Cash at End of Period	1,801	2,168
Cash paid (received) during the period for —
Interest, net of amounts capitalized	519	490
Income taxes, net	(51)	(16)
Noncash transactions —
Accrued property additions at end of period	872	733
Contributions from noncontrolling interests	89	0
Contributions of wind turbine equipment	82	17
Right-of-use assets obtained under finance leases	76	28
Interest capitalized	21	20
ALABAMA POWER CO
Operating Activities:
Net income	363	284
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	248	241
Deferred income taxes	33	10
Allowance for equity funds used during construction	(12)	(10)
Pension, postretirement, and other employee benefits	(29)	(25)
Settlement of asset retirement obligations	(49)	(46)
Other, net	(15)	10
Changes in certain current assets and liabilities —
-Receivables	40	93
-Fossil fuel stock	38	(15)
-Prepayments	(73)	(80)
-Materials and supplies	(4)	(22)
-Other current assets	(11)	(14)
-Accounts payable	(299)	(305)
-Accrued taxes	104	100
-Accrued compensation	(105)	(111)
-Retail fuel cost over recovery	(18)	47
-Other current liabilities	(9)	(12)
Net cash provided from operating activities	214	155
Investing Activities:
Property additions	(466)	(340)
Nuclear decommissioning trust fund purchases	(310)	(81)
Nuclear decommissioning trust fund sales	310	81
Cost of removal, net of salvage	(23)	(15)
Change in construction payables, net	32	(65)
Other investing activities	(9)	(4)
Net cash used for investing activities	(466)	(424)
Redemptions and repurchases —
Pollution control revenue bonds	0	(87)
Capital contributions from parent company	600	610
Payment of common stock dividends	(246)	(239)
Other financing activities	(13)	(11)
Net cash provided from financing activities	341	273
Net Change in Cash, Cash Equivalents, and Restricted Cash	89	4
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	530	894
Cash, Cash Equivalents, and Restricted Cash at End of Period	619	898
Cash paid (received) during the period for —
Interest, net of amounts capitalized	93	92
Noncash transactions —
Accrued property additions at end of period	198	135
Right-of-use assets obtained under leases	1	3
Interest capitalized	3	3
GEORGIA POWER CO
Operating Activities:
Net income	351	331
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	384	396
Deferred income taxes	(86)	(73)
Pension, postretirement, and other employee benefits	(43)	(40)
Settlement of asset retirement obligations	(49)	(33)
Estimated loss on Plant Vogtle Units 3 and 4	48	0
Storm damage accruals	53	53
Retail fuel cost over recovery – long-term	0	90
Other, net	(19)	(52)
Changes in certain current assets and liabilities —
-Receivables	176	22
-Fossil fuel stock	10	(42)
-Other current assets	(7)	(15)
-Accounts payable	(74)	(69)
-Accrued taxes	(110)	(156)
-Accrued compensation	(68)	(87)
-Customer refunds	0	(107)
-Other current liabilities	(77)	(5)
Net cash provided from operating activities	489	213
Investing Activities:
Property additions	(775)	(849)
Nuclear decommissioning trust fund purchases	(241)	(173)
Nuclear decommissioning trust fund sales	236	167
Proceeds from dispositions	1	142
Cost of removal, net of salvage	(40)	(34)
Change in construction payables, net	(103)	(46)
Other investing activities	9	(2)
Net cash used for investing activities	(913)	(795)
Financing Activities:
Increase in notes payable, net	145	11
Proceeds —
Senior notes	750	1,500
Pollution control revenue bonds	0	53
Short-term borrowings	0	200
Redemptions and repurchases —
Pollution control revenue bonds	0	(148)
Senior notes	(325)	(950)
FFB loan	(25)	(16)
Capital contributions from parent company	330	500
Payment of common stock dividends	(412)	(385)
Other financing activities	(19)	(23)
Net cash provided from financing activities	444	742
Net Change in Cash, Cash Equivalents, and Restricted Cash	20	160
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	9	52
Cash, Cash Equivalents, and Restricted Cash at End of Period	29	212
Cash paid (received) during the period for —
Interest, net of amounts capitalized	128	122
Noncash transactions —
Accrued property additions at end of period	445	472
Right-of-use assets obtained under operating leases	3	10
Interest capitalized	15	11
MISSISSIPPI POWER CO
Operating Activities:
Net income	45	32
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	53	44
Other, net	(10)	(3)
Changes in certain current assets and liabilities —
-Receivables	7	14
-Other current assets	1	(10)
-Accounts payable	(30)	(24)
-Accrued taxes	(75)	(54)
-Accrued compensation	(16)	(19)
-Other current liabilities	(13)	3
Net cash provided from operating activities	(38)	(17)
Investing Activities:
Property additions	(45)	(50)
Change in construction payables, net	(8)	(10)
Payments pursuant to LTSAs	(7)	(5)
Other investing activities	(7)	(6)
Net cash used for investing activities	(67)	(71)
Financing Activities:
Increase in notes payable, net	29	0
Proceeds —
Short-term borrowings	0	40
Other long-term debt	0	100
Redemptions and repurchases —
Senior notes	0	(275)
Capital contributions from parent company	100	75
Return of capital to parent company	0	(37)
Payment of common stock dividends	(39)	0
Other financing activities	0	(1)
Net cash provided from financing activities	90	(98)
Net Change in Cash, Cash Equivalents, and Restricted Cash	(15)	(186)
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	39	286
Cash, Cash Equivalents, and Restricted Cash at End of Period	24	100
Cash paid (received) during the period for —
Interest, net of amounts capitalized	16	18
Noncash transactions —
Accrued property additions at end of period	26	25
Interest capitalized	0	0
SOUTHERN POWER CO
Operating Activities:
Net income	65	44
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	125	123
Deferred income taxes	(8)	(36)
Amortization of investment tax credits	(15)	(14)
(Gain) loss on dispositions, net	(39)	(39)
Other, net	(4)	(10)
Changes in certain current assets and liabilities —
-Receivables	23	5
-Prepaid income taxes	16	51
-Other current assets	3	(2)
-Accounts payable	19	(34)
-Accrued taxes	5	8
-Other current liabilities	(3)	(13)
Net cash provided from operating activities	187	83
Investing Activities:
Business acquisitions, net of cash acquired	(345)	0
Property additions	(147)	(47)
Proceeds from dispositions	17	660
Change in construction payables, net	(7)	(15)
Payments pursuant to LTSAs	(27)	(15)
Other investing activities	5	17
Net cash used for investing activities	(504)	600
Financing Activities:
Increase in notes payable, net	140
Decrease in notes payable, net		(449)
Proceeds —
Senior notes	400	0
Redemptions and repurchases —
Short-term borrowings	0	(100)
Return of capital to parent company	(271)	0
Capital contributions from noncontrolling interests	313	16
Distributions to noncontrolling interests	(46)	(48)
Payment of common stock dividends	(51)	(50)
Other financing activities	(7)	(1)
Net cash provided from financing activities	478	(632)
Net Change in Cash, Cash Equivalents, and Restricted Cash	161	51
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	182	279
Cash, Cash Equivalents, and Restricted Cash at End of Period	343	330
Cash paid (received) during the period for —
Interest, net of amounts capitalized	26	28
Income taxes, net	(2)	(5)
Noncash transactions —
Accrued property additions at end of period	60	27
Contributions from noncontrolling interests	89	0
Contributions of wind turbine equipment	82	17
Right-of-use assets obtained under operating leases	65	0
Interest capitalized	1	4
SOUTHERN Co GAS
Operating Activities:
Net income	398	275
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	130	120
Deferred income taxes	160	22
Mark-to-market adjustments	64	13
Natural gas cost under recovery – long-term	(185)	0
Other, net	5	(19)
Changes in certain current assets and liabilities —
-Receivables	74	112
-Natural gas for sale, net of temporary LIFO liquidation	456	246
-Natural gas cost under recovery	(487)	0
-Other current assets	(34)	33
-Accounts payable	(7)	(185)
-Accrued taxes	10	27
-Accrued compensation	0	(42)
-Other current liabilities	(34)	41
Net cash provided from operating activities	550	643
Investing Activities:
Property additions	(251)	(261)
Proceeds from dispositions	0	178
Cost of removal, net of salvage	(16)	(15)
Change in construction payables, net	(47)	(18)
Investment in unconsolidated subsidiaries	(1)	(77)
Other investing activities	7	0
Net cash used for investing activities	(308)	(193)
Financing Activities:
Decrease in notes payable, net	(127)	(39)
Proceeds —
Short-term borrowings	300	0
Redemptions and repurchases —
Redemptions — Medium-term notes	(30)	0
Capital contributions from parent company	39	0
Payment of common stock dividends	(132)	(133)
Other financing activities	0	(13)
Net cash provided from financing activities	50	(185)
Net Change in Cash, Cash Equivalents, and Restricted Cash	292	265
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	19	49
Cash, Cash Equivalents, and Restricted Cash at End of Period	311	314
Cash paid (received) during the period for —
Interest, net of amounts capitalized	52	49
Income taxes, net	(1)	(12)
Noncash transactions —
Accrued property additions at end of period	95	104
Interest capitalized	$ 2	$ 2