Condensed Statements of Common Stockholders' Equity (Unaudited) - APC - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Paid-In Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)	Alabama Power	Alabama Power Common Stock	Alabama Power Paid-In Capital	Alabama Power Retained Earnings (Accumulated Deficit)	Alabama Power Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2020		1,058					31
Beginning balance at Dec. 31, 2020	$ 32,234	$ 5,268	$ 11,834	$ 11,311	$ (395)	$ 9,810	$ 1,222	$ 5,413	$ 3,194	$ (19)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income after dividends on preferred stock	1,135					359			359
Capital contributions from parent company						602		602
Other comprehensive income (loss)	28				28	1				1
Cash dividends on common stock	(678)			(678)		(246)			(246)
Ending balance (in shares) at Mar. 31, 2021		1,060					31
Ending balance at Mar. 31, 2021	33,068	$ 5,273	11,854	11,768	(367)	10,526	$ 1,222	6,015	3,307	(18)
Beginning balance (in shares) at Dec. 31, 2021		1,061					31
Beginning balance at Dec. 31, 2021	32,276	$ 5,279	11,950	10,929	(237)	10,713	$ 1,222	6,056	3,448	(13)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income after dividends on preferred stock	1,032					347			347
Capital contributions from parent company						626		626
Other comprehensive income (loss)	42				42
Cash dividends on common stock	(702)			(702)		(254)			(254)
Ending balance (in shares) at Mar. 31, 2022		1,064					31
Ending balance at Mar. 31, 2022	$ 32,629	$ 5,286	$ 11,994	$ 11,261	$ (195)	$ 11,432	$ 1,222	$ 6,682	$ 3,541	$ (13)