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, 2020	$ 32,234	$ 11,834	$ 11,311	$ (395)	$ 4,262	$ 6,631	$ 2,369	$ 914	$ 1,522	$ (67)	$ 4,262
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income						65	97		97		(32)
Return of capital to parent company						(271)	(271)	(271)
Other comprehensive income (loss)	28			28		16	16			16
Cash dividends on common stock	(678)		(678)			(51)	(51)		(51)
Capital contributions from noncontrolling interests	403				403	403					403
Distributions to noncontrolling interests	(46)				(46)	(46)					(46)
Other	1	2			(1)	(3)	(2)	(2)	1	(1)	(1)
Ending balance at Mar. 31, 2021	33,068	11,854	11,768	(367)	4,586	6,744	2,158	641	1,569	(52)	4,586
Beginning balance at Dec. 31, 2020	32,234	11,834	11,311	(395)	4,262	6,631	2,369	914	1,522	(67)	4,262
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	2,592					184
Ending balance at Sep. 30, 2021	33,219	11,932	11,844	(319)	4,530	6,707	2,177	643	1,581	(47)	4,530
Beginning balance at Mar. 31, 2021	33,068	11,854	11,768	(367)	4,586	6,744	2,158	641	1,569	(52)	4,586
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income						36	36		36		0
Other comprehensive income (loss)	12			12		(3)	(3)			(3)
Cash dividends on common stock	(699)		(699)			(51)	(51)		(51)
Capital contributions from noncontrolling interests	29				29	29					29
Distributions to noncontrolling interests	(68)				(68)	(68)					(68)
Other	0	1	1			3	3	2		1
Ending balance at Jun. 30, 2021	32,746	11,886	11,442	(355)	4,547	6,690	2,143	643	1,554	(54)	4,547
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,110					83	78		78		5
Other comprehensive income (loss)	36			36		7	7			7
Cash dividends on common stock	(700)		(700)			(51)	(51)		(51)
Capital contributions from noncontrolling interests	72				72	73					73
Distributions to noncontrolling interests	(94)				(94)	(95)					(95)
Other	(7)	(10)	1
Ending balance at Sep. 30, 2021	33,219	11,932	11,844	(319)	4,530	6,707	2,177	643	1,581	(47)	4,530
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]
Net income						27	72		72		(45)
Other comprehensive income (loss)	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]
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]
Net income						76	98		98		(22)
Capital contributions from parent company						322	322	322
Other comprehensive income (loss)	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]
Net income	1,487					107	95		95		12
Capital contributions from parent company						9	9	9
Other comprehensive income (loss)	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