Condensed Statements of Common Stockholders' Equity (Unaudited) - MPC - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Paid-In Capital	Retained Earnings (Accumulated Deficit)	Mississippi Power	Mississippi Power Common Stock	Mississippi Power Paid-In Capital	Mississippi Power Retained Earnings (Accumulated Deficit)
Beginning balance (in shares) at Dec. 31, 2021						1
Beginning balance at Dec. 31, 2021	$ 32,276	$ 5,279	$ 11,950	$ 10,929	$ 1,867	$ 38	$ 4,582	$ (2,753)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income					42			42
Capital contributions from parent company					51		51
Cash dividends on common stock	(702)			(702)	(43)			(43)
Ending balance (in shares) at Mar. 31, 2022						1
Ending balance at Mar. 31, 2022	32,629	5,286	11,994	11,261	1,917	$ 38	4,633	(2,754)
Beginning balance (in shares) at Dec. 31, 2021						1
Beginning balance at Dec. 31, 2021	32,276	5,279	11,950	10,929	1,867	$ 38	4,582	(2,753)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	3,566				150
Ending balance (in shares) at Sep. 30, 2022						1
Ending balance at Sep. 30, 2022	35,476	5,417	13,657	12,374	1,946	$ 38	4,639	(2,731)
Beginning balance (in shares) at Mar. 31, 2022						1
Beginning balance at Mar. 31, 2022	32,629	5,286	11,994	11,261	1,917	$ 38	4,633	(2,754)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income					45			45
Capital contributions from parent company					1		1
Cash dividends on common stock	(723)			(723)	(42)			(42)
Ending balance (in shares) at Jun. 30, 2022						1
Ending balance at Jun. 30, 2022	33,013	5,288	12,033	11,645	1,921	$ 38	4,634	(2,751)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,487				62			62
Capital contributions from parent company					5		5
Cash dividends on common stock	(741)			(741)	(42)			(42)
Ending balance (in shares) at Sep. 30, 2022						1
Ending balance at Sep. 30, 2022	35,476	5,417	13,657	12,374	1,946	$ 38	4,639	(2,731)
Beginning balance (in shares) at Dec. 31, 2022						1
Beginning balance at Dec. 31, 2022	34,532	5,417	13,673	11,538	1,931	$ 38	4,652	(2,759)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income					58			58
Cash dividends on common stock	(742)			(742)	(46)			(46)
Ending balance (in shares) at Mar. 31, 2023						1
Ending balance at Mar. 31, 2023	34,562	5,421	13,715	11,658	1,943	$ 38	4,652	(2,747)
Beginning balance (in shares) at Dec. 31, 2022						1
Beginning balance at Dec. 31, 2022	34,532	5,417	13,673	11,538	1,931	$ 38	4,652	(2,759)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	3,053				173
Ending balance (in shares) at Sep. 30, 2023						1
Ending balance at Sep. 30, 2023	35,304	5,422	13,751	12,391	1,974	$ 38	4,661	(2,725)
Beginning balance (in shares) at Mar. 31, 2023						1
Beginning balance at Mar. 31, 2023	34,562	5,421	13,715	11,658	1,943	$ 38	4,652	(2,747)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income					40			40
Capital contributions from parent company					12		12
Cash dividends on common stock	(764)			(764)	(47)			(47)
Ending balance (in shares) at Jun. 30, 2023						1
Ending balance at Jun. 30, 2023	34,648	5,422	13,742	11,732	1,948	$ 38	4,664	(2,754)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,432				75			75
Return of capital to parent company					(3)		(3)
Cash dividends on common stock	(765)			(765)	(46)			(46)
Ending balance (in shares) at Sep. 30, 2023						1
Ending balance at Sep. 30, 2023	$ 35,304	$ 5,422	$ 13,751	$ 12,391	$ 1,974	$ 38	$ 4,661	$ (2,725)