Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - SPC - USD ($) $ in Millions	Total	Paid-In Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests	SOUTHERN POWER CO	SOUTHERN POWER CO Total Common Stockholders' Equity	SOUTHERN POWER CO Paid-In Capital	SOUTHERN POWER CO Retained Earnings (Accumulated Deficit)	SOUTHERN POWER CO Accumulated Other Comprehensive Income (Loss)	SOUTHERN POWER CO Noncontrolling Interests
Beginning balance at Dec. 31, 2021	$ 32,276	$ 11,950	$ 10,929	$ (237)	$ 4,402	$ 6,598	$ 2,196	$ 638	$ 1,585	$ (27)	$ 4,402
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income						27	72		72		(45)
Other comprehensive income	42			42		5	5			5
Cash dividends on common stock	(702)		(702)			(49)	(49)		(49)
Capital contributions from noncontrolling interests	73				73	73					73
Distributions to noncontrolling interests	(98)				(98)	(98)					(98)
Other	7	7	2
Ending balance at Mar. 31, 2022	32,629	11,994	11,261	(195)	4,332	6,556	2,224	638	1,608	(22)	4,332
Beginning balance at Dec. 31, 2021	32,276	11,950	10,929	(237)	4,402	6,598	2,196	638	1,585	(27)	4,402
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income	3,566					210
Ending balance at Sep. 30, 2022	35,476	13,657	12,374	(157)	4,237	6,880	2,643	969	1,701	(27)	4,237
Beginning balance at Mar. 31, 2022	32,629	11,994	11,261	(195)	4,332	6,556	2,224	638	1,608	(22)	4,332
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income						76	98		98		(22)
Capital contributions from parent company						322	322	322
Other comprehensive income	11			11		3	3			3
Cash dividends on common stock	(723)		(723)			(50)	(50)		(50)
Distributions to noncontrolling interests	(28)				(28)	(28)					(28)
Other	2	4
Ending balance at Jun. 30, 2022	33,013	12,033	11,645	(184)	4,282	6,879	2,597	960	1,656	(19)	4,282
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income	1,487					107	95		95		12
Capital contributions from parent company						9	9	9
Other comprehensive income	28			28		(7)	(7)			(7)
Cash dividends on common stock	(741)		(741)			(49)	(49)		(49)
Distributions to noncontrolling interests	(57)				(57)	(57)					(57)
Other	(8)	(4)	(2)	(1)		(2)	(2)		(1)	(1)
Ending balance at Sep. 30, 2022	35,476	13,657	12,374	(157)	4,237	6,880	2,643	969	1,701	(27)	4,237
Beginning balance at Dec. 31, 2022	34,532	13,673	11,538	(167)	4,124	6,916	2,792	1,069	1,741	(18)	4,124
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income						39	102		102		(63)
Other comprehensive income	(44)			(44)		(7)	(7)			(7)
Cash dividends on common stock	(742)		(742)			(63)	(63)		(63)
Capital contributions from noncontrolling interests	21				21	21					21
Distributions to noncontrolling interests	(48)				(48)	(48)					(48)
Other	0	2
Ending balance at Mar. 31, 2023	34,562	13,715	11,658	(211)	4,034	6,858	2,824	1,069	1,780	(25)	4,034
Beginning balance at Dec. 31, 2022	34,532	13,673	11,538	(167)	4,124	6,916	2,792	1,069	1,741	(18)	4,124
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income	3,053					220
Ending balance at Sep. 30, 2023	35,304	13,751	12,391	(130)	3,927	6,843	2,916	1,087	1,839	(10)	3,927
Beginning balance at Mar. 31, 2023	34,562	13,715	11,658	(211)	4,034	6,858	2,824	1,069	1,780	(25)	4,034
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income						70	85		85		(15)
Capital contributions from parent company						14	14	14
Other comprehensive income	43			43		10	10			10
Cash dividends on common stock	(764)		(764)			(63)	(63)		(63)
Distributions to noncontrolling interests	(42)				(42)	(42)					(42)
Other	0	2			(1)	0	1			1	(1)
Ending balance at Jun. 30, 2023	34,648	13,742	11,732	(168)	3,976	6,847	2,871	1,083	1,802	(14)	3,976
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated Net Income	1,432					110	100		100		10
Capital contributions from parent company						3	3	3
Other comprehensive income	38			38		4	4			4
Cash dividends on common stock	(765)		(765)			(63)	(63)		(63)
Distributions to noncontrolling interests	(59)				(59)	(59)					(59)
Other	(1)	(2)	2			1	1	1	0	0	0
Ending balance at Sep. 30, 2023	$ 35,304	$ 13,751	$ 12,391	$ (130)	$ 3,927	$ 6,843	$ 2,916	$ 1,087	$ 1,839	$ (10)	$ 3,927