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, 2020		1,058					1
Beginning balance at Dec. 31, 2020	$ 32,234	$ 5,268	$ 11,834	$ 11,311	$ (395)	$ 1,742	$ 38	$ 4,460	$ (2,754)	$ (2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,135					45			45
Capital contributions from parent company						100		100
Cash dividends on common stock	(678)			(678)		(39)			(39)
Ending balance (in shares) at Mar. 31, 2021		1,060					1
Ending balance at Mar. 31, 2021	33,068	$ 5,273	11,854	11,768	(367)	1,848	$ 38	4,560	(2,748)	(2)
Beginning balance (in shares) at Dec. 31, 2021		1,061					1
Beginning balance at Dec. 31, 2021	32,276	$ 5,279	11,950	10,929	(237)	1,867	$ 38	4,582	(2,753)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,032					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		1,064					1
Ending balance at Mar. 31, 2022	$ 32,629	$ 5,286	$ 11,994	$ 11,261	$ (195)	$ 1,917	$ 38	$ 4,633	$ (2,754)	$ 0