Consolidated Statements of Cash Flows - GAS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Activities:
Consolidated net income	$ 3,849	$ 3,428	$ 2,309
Adjustments to reconcile consolidated net income to net cash provided from operating activities —
Depreciation and amortization, total	4,986	4,064	3,973
Deferred income taxes	63	670	(49)
Natural gas cost under recovery – long-term	0	207	(207)
Other, net	(138)	(25)	(89)
Changes in certain current assets and liabilities —
-Receivables	482	(771)	(77)
-Natural gas cost under recovery	108	158	(266)
-Other current assets	(106)	(186)	(270)
-Accounts payable	(863)	1,021	(8)
-Other current liabilities	214	204	(258)
Net cash provided from operating activities	7,553	6,302	6,169
Investing Activities:
Property additions	(9,095)	(7,923)	(7,586)
Cost of removal, net of salvage	(592)	(649)	(442)
Change in construction payables, net	18	203	(124)
Proceeds from dispositions	164	275	917
Other investing activities	(43)	(133)	75
Net cash used for investing activities	(9,668)	(8,430)	(7,353)
Financing Activities:
Increase (decrease) in notes payable, net		(337)
Increase (decrease) in notes payable, net	973		530
Proceeds —
Short-term borrowings	350	2,650	325
Redemptions and repurchases —
Short-term borrowings	(1,630)	(1,150)	(25)
Payment of common stock dividends	(3,035)	(2,907)	(2,777)
Other financing activities	(160)	(218)	(266)
Net cash provided from financing activities	999	2,336	1,945
Net Change in Cash, Cash Equivalents, and Restricted Cash	(1,116)	208	761
Cash, Cash Equivalents, and Restricted Cash at Beginning of Year	2,037	1,829	1,068
Cash, Cash Equivalents, and Restricted Cash at End of Year	921	2,037	1,829
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	2,184	1,758	1,718
Income taxes, net	132	146	93
Noncash transactions —
Accrued property additions at year-end	1,027	1,024	866
Southern Company Gas
Operating Activities:
Consolidated net income	615	572	539
Adjustments to reconcile consolidated net income to net cash provided from operating activities —
Depreciation and amortization, total	582	558	536
Deferred income taxes	126	17	259
Impairment charges	0	131	84
Gain on dispositions, net	(7)	(4)	(127)
Mark-to-market adjustments	(7)	12	194
Natural gas cost under recovery – long-term	0	207	(207)
Estimated loss on regulatory disallowance	(96)	0	0
Other, net	(60)	(32)	(30)
Changes in certain current assets and liabilities —
-Receivables	431	(345)	(143)
-Natural gas for sale, net of temporary LIFO liquidation	19	(77)	8
-Prepaid income taxes	(11)	19	(82)
-Natural gas cost under recovery	108	158	(266)
-Other current assets	(17)	(6)	(116)
-Accounts payable	(276)	299	40
-Natural gas cost over recovery	214	0	0
-Other current liabilities	(51)	10	(26)
Net cash provided from operating activities	1,762	1,519	663
Investing Activities:
Property additions	(1,561)	(1,533)	(1,421)
Cost of removal, net of salvage	(104)	(112)	(106)
Change in construction payables, net	(38)	65	(29)
Investments in unconsolidated subsidiaries	(11)	(165)	(5)
Proceeds from dispositions	42	150	150
Other investing activities	16	15	32
Net cash used for investing activities	(1,656)	(1,580)	(1,379)
Financing Activities:
Increase (decrease) in notes payable, net	(153)	(341)
Increase (decrease) in notes payable, net			585
Proceeds —
Senior notes	500	500	450
First mortgage bonds	275	175	200
Short-term borrowings	0	50	300
Other long-term debt	37	22	0
Redemptions and repurchases —
Senior notes	0	0	(300)
Short-term borrowings	(200)	(150)	0
Medium-term notes	(350)	(46)	(30)
First mortgage bonds	(50)	0	0
Capital contributions from parent company	373	406	72
Payment of common stock dividends	(585)	(519)	(530)
Other financing activities	(1)	(1)	(2)
Net cash provided from financing activities	(154)	96	745
Net Change in Cash, Cash Equivalents, and Restricted Cash	(48)	35	29
Cash, Cash Equivalents, and Restricted Cash at Beginning of Year	83	48	19
Cash, Cash Equivalents, and Restricted Cash at End of Year	35	83	48
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	291	258	244
Income taxes, net	91	208	57
Noncash transactions —
Accrued property additions at year-end	$ 139	$ 177	$ 113