Condensed Consolidated Statements of Cash Flows (Unaudited) - GAS - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Operating Activities:
Net income	$ 3,925	$ 3,867
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	4,425	3,916
Deferred income taxes	355	607
Other, net	(22)	(121)
Changes in certain current assets and liabilities —
Receivables	200	(233)
Other current assets	(187)	(181)
Accounts payable	(747)	(161)
Other current liabilities	(267)	(43)
Net cash provided from operating activities	7,205	7,615
Investing Activities:
Property additions	(8,452)	(6,206)
Cost of removal, net of salvage	(479)	(444)
Change in construction payables, net	69	(119)
Other investing activities	(103)	(279)
Net cash used for investing activities	(9,599)	(6,678)
Financing Activities:
Decrease in notes payable, net	(993)	(1,264)
Proceeds —
Payment of common stock dividends	(2,254)	(2,220)
Other financing activities	(176)	(157)
Net cash provided from (used for) financing activities	4,635	(803)
Net Change in Cash, Cash Equivalents, and Restricted Cash	2,241	134
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	1,101	921
Cash, Cash Equivalents, and Restricted Cash at End of Period	3,342	1,055
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	2,173	2,015
Income taxes, net (excludes credit transfers)	231	131
Noncash transactions —
Accrued property additions at end of period	1,177	937
Right-of-use assets obtained under operating leases	131	126
SOUTHERN Co GAS
Operating Activities:
Net income	549	555
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	512	466
Deferred income taxes	188	206
Other, net	0	7
Changes in certain current assets and liabilities —
Receivables	328	386
Natural gas for sale, net of temporary LIFO liquidation	(27)	3
Prepaid income taxes	(34)	35
Other current assets	8	(92)
Accounts payable	(103)	(105)
Natural gas cost over recovery	(30)	12
Other current liabilities	(13)	(66)
Net cash provided from operating activities	1,378	1,407
Investing Activities:
Property additions	(1,179)	(1,064)
Cost of removal, net of salvage	(70)	(63)
Change in construction payables, net	45	(13)
Investment in unconsolidated subsidiaries	(43)	(64)
Returned investment in unconsolidated subsidiaries	128	4
Other investing activities	0	4
Net cash used for investing activities	(1,119)	(1,196)
Financing Activities:
Decrease in notes payable, net	(312)	(352)
Proceeds —
Senior notes	850	450
First mortgage bonds	0	156
Other long-term debt	0	9
Redemptions — First mortgage bonds	(50)	0
Return of capital to parent company	(23)	0
Capital contributions from parent company	40	0
Payment of common stock dividends	(446)	(454)
Other financing activities	(16)	(10)
Net cash provided from (used for) financing activities	43	(201)
Net Change in Cash, Cash Equivalents, and Restricted Cash	302	10
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	44	35
Cash, Cash Equivalents, and Restricted Cash at End of Period	346	45
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	297	258
Income taxes, net (excludes credit transfers)	16	(54)
Noncash transactions —
Accrued property additions at end of period	87	126
Right-of-use assets obtained under operating leases	60	1
Return of capital to parent company	$ 33	$ 0