Condensed Statements of Common Stockholders' Equity (Unaudited) - MPC - USD ($) shares in Millions, $ in Millions	Total	Paid-In Capital	Retained Earnings (Accumulated Deficit)	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, 2023					1
Beginning balance at Dec. 31, 2023				$ 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				5				5
Cash dividends on common stock	$ (766)		$ (766)	(47)			(47)
Other	7	$ 10	(1)
Ending balance (in shares) at Mar. 31, 2024					1
Ending balance at Mar. 31, 2024				2,012	$ 38	4,722	(2,753)	5
Beginning balance (in shares) at Dec. 31, 2023					1
Beginning balance at Dec. 31, 2023				2,003	$ 38	4,721	(2,756)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	2,332			111
Other comprehensive income				5
Ending balance (in shares) at Jun. 30, 2024					1
Ending balance at Jun. 30, 2024				2,084	$ 38	4,780	(2,739)	5
Beginning balance (in shares) at Mar. 31, 2024					1
Beginning balance at Mar. 31, 2024				2,012	$ 38	4,722	(2,753)	5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,203			61			61
Capital contributions from parent company				58		58
Other comprehensive income				0
Cash dividends on common stock	(788)		(788)	(47)			(47)
Other	1	3
Ending balance (in shares) at Jun. 30, 2024					1
Ending balance at Jun. 30, 2024				2,084	$ 38	4,780	(2,739)	5
Beginning balance (in shares) at Dec. 31, 2024					1
Beginning balance at Dec. 31, 2024				2,089	$ 38	4,791	(2,745)	5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income				55			55
Capital contributions from parent company				51		51
Cash dividends on common stock	(791)		(791)	(48)			(48)
Other	(5)	(1)	(2)	(1)				(1)
Ending balance (in shares) at Mar. 31, 2025					1
Ending balance at Mar. 31, 2025				2,146	$ 38	4,842	(2,738)	4
Beginning balance (in shares) at Dec. 31, 2024					1
Beginning balance at Dec. 31, 2024				2,089	$ 38	4,791	(2,745)	5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	2,214			114
Other comprehensive income				0
Ending balance (in shares) at Jun. 30, 2025					1
Ending balance at Jun. 30, 2025				2,164	$ 38	4,849	(2,727)	4
Beginning balance (in shares) at Mar. 31, 2025					1
Beginning balance at Mar. 31, 2025				2,146	$ 38	4,842	(2,738)	4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	880			59			59
Capital contributions from parent company				7		7
Other comprehensive income				0
Cash dividends on common stock	(815)		(815)	(49)			(49)
Other	$ 6	$ 6	$ 1	1			1
Ending balance (in shares) at Jun. 30, 2025					1
Ending balance at Jun. 30, 2025				$ 2,164	$ 38	$ 4,849	$ (2,727)	$ 4