Consolidated Statements of Cash Flows - GAS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating Activities:
Consolidated net income	$ 3,428	$ 2,309	$ 3,103
Adjustments to reconcile consolidated net income to net cash provided from operating activities —
Depreciation and amortization, total	4,064	3,973	3,905
Deferred income taxes	670	(49)	(241)
Gain on dispositions, net	(42)	(176)	(66)
Natural gas cost under recovery – long-term	207	(207)	0
Other, net	17	87	(75)
Changes in certain current assets and liabilities —
-Receivables	(769)	(81)	(222)
-Natural gas cost under recovery	158	(266)	0
-Other current assets	(288)	(270)	(132)
-Accounts payable	1,021	(8)	(27)
-Other current liabilities	153	(204)	173
Net cash provided from operating activities	6,302	6,169	6,696
Investing Activities:
Property additions	(7,923)	(7,586)	(7,522)
Cost of removal, net of salvage	(649)	(442)	(361)
Proceeds from dispositions	275	917	1,049
Other investing activities	70	(49)	21
Net cash used for investing activities	(8,430)	(7,353)	(7,030)
Financing Activities:
Increase (decrease) in notes payable, net		530
Increase (decrease) in notes payable, net	(337)		(1,096)
Proceeds —
Short-term borrowings	2,650	325	615
Redemptions and repurchases —
Short-term borrowings	(1,150)	(25)	(840)
Payment of common stock dividends	(2,907)	(2,777)	(2,685)
Other financing activities	(218)	(266)	(325)
Net cash provided from (used for) financing activities	2,336	1,945	(576)
Net Change in Cash, Cash Equivalents, and Restricted Cash	208	761	(910)
Cash, Cash Equivalents, and Restricted Cash at Beginning of Year	1,829	1,068	1,978
Cash, Cash Equivalents, and Restricted Cash at End of Year	2,037	1,829	1,068
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	1,758	1,718	1,683
Income taxes, net	146	93	64
Noncash transactions —
Accrued property additions at year-end	1,024	866	989
Southern Company Gas
Operating Activities:
Consolidated net income	572	539	590
Adjustments to reconcile consolidated net income to net cash provided from operating activities —
Depreciation and amortization, total	558	536	500
Deferred income taxes	17	259	56
Impairment charges	131	84	0
Gain on dispositions, net	(4)	(127)	(22)
Mark-to-market adjustments	12	194	61
Natural gas cost under recovery – long-term	207	(207)	0
Other, net	(32)	(30)	(29)
Changes in certain current assets and liabilities —
-Receivables	(345)	(143)	(93)
-Natural gas for sale, net of temporary LIFO liquidation	(77)	8	18
-Prepaid income taxes	19	(82)	19
-Natural gas cost under recovery	158	(266)	0
-Other current assets	(6)	(116)	(10)
-Accounts payable	299	40	103
-Other current liabilities	10	(26)	14
Net cash provided from operating activities	1,519	663	1,207
Investing Activities:
Property additions	(1,533)	(1,421)	(1,471)
Cost of removal, net of salvage	(112)	(106)	(100)
Change in construction payables, net	65	(29)	20
Investments in unconsolidated subsidiaries	(165)	(5)	(79)
Proceeds from dispositions	150	150	211
Other investing activities	15	32	2
Net cash used for investing activities	(1,580)	(1,379)	(1,417)
Financing Activities:
Increase (decrease) in notes payable, net		585
Increase (decrease) in notes payable, net	(341)		(326)
Proceeds —
Senior notes	500	450	500
Short-term borrowings	50	300	0
First mortgage bonds	175	200	325
Other long-term debt	22	0	0
Redemptions and repurchases —
Senior notes	0	(300)	0
Medium-term notes	(46)	(30)	0
Short-term borrowings	(150)	0	0
Capital contributions from parent company	406	72	216
Payment of common stock dividends	(519)	(530)	(533)
Other financing activities	(1)	(2)	(2)
Net cash provided from (used for) financing activities	96	745	180
Net Change in Cash, Cash Equivalents, and Restricted Cash	35	29	(30)
Cash, Cash Equivalents, and Restricted Cash at Beginning of Year	48	19	49
Cash, Cash Equivalents, and Restricted Cash at End of Year	83	48	19
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	258	244	232
Income taxes, net	208	57	25
Noncash transactions —
Accrued property additions at year-end	$ 177	$ 113	$ 142