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, 2023							31
Beginning balance at Dec. 31, 2023						$ 12,333	$ 1,222	$ 7,125	$ 3,993	$ (7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income						333			333
Capital contributions from parent company						427		427
Cash dividends on common stock	$ (766)			$ (766)		(295)			(295)
Other	7		$ 10	(1)		(1)			(1)
Ending balance (in shares) at Mar. 31, 2024							31
Ending balance at Mar. 31, 2024						12,797	$ 1,222	7,552	4,030	(7)
Beginning balance (in shares) at Dec. 31, 2023							31
Beginning balance at Dec. 31, 2023						12,333	$ 1,222	7,125	3,993	(7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	3,867					1,195
Other comprehensive income						1
Ending balance (in shares) at Sep. 30, 2024							31
Ending balance at Sep. 30, 2024						13,135	$ 1,222	7,618	4,301	(6)
Beginning balance (in shares) at Mar. 31, 2024							31
Beginning balance at Mar. 31, 2024						12,797	$ 1,222	7,552	4,030	(7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income						369			369
Capital contributions from parent company						50		50
Other comprehensive income						1				1
Cash dividends on common stock	(788)			(788)		(296)			(296)
Other	1		3
Ending balance (in shares) at Jun. 30, 2024							31
Ending balance at Jun. 30, 2024						12,921	$ 1,222	7,602	4,103	(6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,535					493			493
Capital contributions from parent company						16		16
Other comprehensive income						0
Cash dividends on common stock	(789)			(789)		(295)			(295)
Other	4		(2)
Ending balance (in shares) at Sep. 30, 2024							31
Ending balance at Sep. 30, 2024						13,135	$ 1,222	7,618	4,301	(6)
Beginning balance (in shares) at Dec. 31, 2024							31
Beginning balance at Dec. 31, 2024						13,088	$ 1,222	7,657	4,214	(5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income						375			375
Capital contributions from parent company						527		527
Other comprehensive income						1				1
Cash dividends on common stock	(791)			(791)		(305)			(305)
Other	(5)		(1)	(2)		(1)				(1)
Ending balance (in shares) at Mar. 31, 2025							31
Ending balance at Mar. 31, 2025						13,685	$ 1,222	8,184	4,284	(5)
Beginning balance (in shares) at Dec. 31, 2024							31
Beginning balance at Dec. 31, 2024						13,088	$ 1,222	7,657	4,214	(5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	3,925					1,343
Other comprehensive income						2
Ending balance (in shares) at Sep. 30, 2025							31
Ending balance at Sep. 30, 2025						14,114	$ 1,222	8,253	4,643	(4)
Beginning balance (in shares) at Mar. 31, 2025							31
Beginning balance at Mar. 31, 2025						13,685	$ 1,222	8,184	4,284	(5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income						381			381
Capital contributions from parent company						38		38
Cash dividends on common stock	(815)			(815)		(304)			(304)
Other	6		6	1		0			(1)	1
Ending balance (in shares) at Jun. 30, 2025							31
Ending balance at Jun. 30, 2025						13,800	$ 1,222	8,222	4,360	(4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,711					588			588
Capital contributions from parent company						31		31
Other comprehensive income						1				1
Cash dividends on common stock	(815)			(815)		(305)			(305)
Other	$ (4)	$ 1	$ (10)	$ 1	$ (1)	(1)				(1)
Ending balance (in shares) at Sep. 30, 2025							31
Ending balance at Sep. 30, 2025						$ 14,114	$ 1,222	$ 8,253	$ 4,643	$ (4)