Condensed Consolidated Statements of Cash Flows (Unaudited) - GAS - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Operating Activities:
Net income (loss)	$ 799	$ 991
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	1,233	989
Natural gas cost under recovery – long-term	0	162
Other, net	51	79
Changes in certain current assets and liabilities —
Receivables	319	(217)
Natural gas for sale, net of temporary LIFO liquidation	267	450
Other current assets	143	8
Accounts payable	(1,056)	132
Accrued taxes	(237)	(58)
Other current liabilities	(28)	35
Net cash provided from operating activities	844	1,592
Investing Activities:
Property additions	(1,850)	(1,419)
Cost of removal, net of salvage	(135)	(227)
Construction payables	(140)	23
Other investing activities	(91)	(18)
Net cash used for investing activities	(2,118)	(1,555)
Financing Activities:
Short-term borrowings	(400)	(100)
Payment of common stock dividends	(742)	(702)
Other financing activities	(83)	(115)
Net cash provided from (used for) financing activities	454	(193)
Net Change in Cash, Cash Equivalents, and Restricted Cash	(820)	(156)
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	2,037	1,829
Cash, Cash Equivalents, and Restricted Cash at End of Period	1,217	1,673
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	652	515
Noncash transactions — Accrued property additions at end of period	833	863
SOUTHERN Co GAS
Operating Activities:
Net income (loss)	309	319
Adjustments to reconcile net income to net cash provided from operating activities —
Depreciation and amortization, total	141	137
Deferred income taxes	27	5
Mark-to-market adjustments	13	(38)
Natural gas cost under recovery – long-term	0	162
Other, net	(15)	41
Changes in certain current assets and liabilities —
Receivables	266	(115)
Natural gas for sale, net of temporary LIFO liquidation	267	450
Prepaid income taxes	33	34
Other current assets	90	(1)
Accounts payable	(303)	(23)
Accrued taxes	36	54
Natural gas cost over recovery	117	0
Other current liabilities	(3)	(1)
Net cash provided from operating activities	978	1,024
Investing Activities:
Property additions	(299)	(247)
Cost of removal, net of salvage	(24)	(20)
Construction payables	(53)	(5)
Other investing activities	(3)	1
Net cash used for investing activities	(379)	(271)
Financing Activities:
Decrease in notes payable, net	(448)	(577)
Short-term borrowings	(200)	(100)
Capital contributions from parent company	192	39
Payment of common stock dividends	(146)	(130)
Other financing activities	9	0
Net cash provided from (used for) financing activities	(593)	(768)
Net Change in Cash, Cash Equivalents, and Restricted Cash	6	(15)
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	83	48
Cash, Cash Equivalents, and Restricted Cash at End of Period	89	33
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	76	55
Noncash transactions — Accrued property additions at end of period	$ 124	$ 107