Condensed Statements of Common Stockholders' Equity (Unaudited) - MPC - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Paid-In Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)	Mississippi Power	Mississippi Power Common Stock	Mississippi Power Paid-In Capital	Mississippi Power Retained Earnings (Accumulated Deficit)	Mississippi Power Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2022							1
Beginning balance at Dec. 31, 2022	$ 34,532	$ 5,417	$ 13,673	$ 11,538	$ (167)	$ 1,931	$ 38	$ 4,652	$ (2,759)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income						58			58
Other comprehensive income (loss)	(44)				(44)
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	(211)	1,943	$ 38	4,652	(2,747)	0
Beginning balance (in shares) at Dec. 31, 2022							1
Beginning balance at Dec. 31, 2022	34,532	5,417	13,673	11,538	(167)	1,931	$ 38	4,652	(2,759)	0
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	(130)	1,974	$ 38	4,661	(2,725)	0
Beginning balance (in shares) at Mar. 31, 2023							1
Beginning balance at Mar. 31, 2023	34,562	5,421	13,715	11,658	(211)	1,943	$ 38	4,652	(2,747)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income						40			40
Capital contributions from parent company						12		12
Other comprehensive income (loss)	43				43
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	(168)	1,948	$ 38	4,664	(2,754)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,432					75			75
Return of capital to parent company						(3)		(3)
Other comprehensive income (loss)	38				38
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	(130)	1,974	$ 38	4,661	(2,725)	0
Beginning balance (in shares) at Dec. 31, 2023							1
Beginning balance at Dec. 31, 2023	35,225	5,423	13,775	12,482	(177)	2,003	$ 38	4,721	(2,756)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income						50			50
Capital contributions from parent company						1		1
Other comprehensive income (loss)	37				37	5				5
Cash dividends on common stock	(766)			(766)		(47)			(47)
Ending balance (in shares) at Mar. 31, 2024							1
Ending balance at Mar. 31, 2024	35,614	5,431	13,846	12,844	(140)	2,012	$ 38	4,722	(2,753)	5
Beginning balance (in shares) at Dec. 31, 2023							1
Beginning balance at Dec. 31, 2023	35,225	5,423	13,775	12,482	(177)	2,003	$ 38	4,721	(2,756)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	3,794					186
Ending balance (in shares) at Sep. 30, 2024							1
Ending balance at Sep. 30, 2024	36,905	5,441	14,048	14,005	(139)	2,115	$ 38	4,783	(2,711)	5
Beginning balance (in shares) at Mar. 31, 2024							1
Beginning balance at Mar. 31, 2024	35,614	5,431	13,846	12,844	(140)	2,012	$ 38	4,722	(2,753)	5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income						61			61
Capital contributions from parent company						58		58
Other comprehensive income (loss)	10				10
Cash dividends on common stock	(788)			(788)		(47)			(47)
Ending balance (in shares) at Jun. 30, 2024							1
Ending balance at Jun. 30, 2024	36,111	5,436	13,947	13,259	(130)	2,084	$ 38	4,780	(2,739)	5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,535					75			75
Capital contributions from parent company						3		3
Other comprehensive income (loss)	(9)				(9)
Cash dividends on common stock	(789)			(789)		(47)			(47)
Ending balance (in shares) at Sep. 30, 2024							1
Ending balance at Sep. 30, 2024	$ 36,905	$ 5,441	$ 14,048	$ 14,005	$ (139)	$ 2,115	$ 38	$ 4,783	$ (2,711)	$ 5