Consolidated Statements of Common Stockholders Equity (USD $)	Total		Common Stock	Treasury Stock	Paid In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss) [Member]	Preferred and Preference Stock of Subsidiaries	Alabama Power [Member]	Alabama Power [Member] Common Stock	Alabama Power [Member] Paid In Capital	Alabama Power [Member] Retained Earnings	Alabama Power [Member] Accumulated Other Comprehensive Income (Loss) [Member]	Georgia Power [Member]	Georgia Power [Member] Common Stock	Georgia Power [Member] Paid In Capital	Georgia Power [Member] Retained Earnings	Georgia Power [Member] Accumulated Other Comprehensive Income (Loss) [Member]	Gulf Power [Member]	Gulf Power [Member] Common Stock	Gulf Power [Member] Paid In Capital	Gulf Power [Member] Retained Earnings	Gulf Power [Member] Accumulated Other Comprehensive Income (Loss) [Member]	Mississippi Power [Member]	Mississippi Power [Member] Common Stock	Mississippi Power [Member] Paid In Capital	Mississippi Power [Member] Retained Earnings	Mississippi Power [Member] Accumulated Other Comprehensive Income (Loss) [Member]	Southern Power [Member]	Southern Power [Member] Common Stock	Southern Power [Member] Paid In Capital	Southern Power [Member] Retained Earnings	Southern Power [Member] Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance at Dec. 31, 2009	$ 15,585,000,000		$ 4,101,000,000	$ (15,000,000)	$ 2,995,000,000	$ 7,885,000,000	$ (88,000,000)	$ 707,000,000	$ 5,237,000,000	$ 1,222,000,000	$ 2,119,000,000	$ 1,901,000,000	$ (5,000,000)	$ 7,903,000,000	$ 398,000,000	$ 4,593,000,000	$ 2,933,000,000	$ (21,000,000)	$ 1,004,292,000	$ 253,060,000	$ 534,577,000	$ 219,117,000	$ (2,462,000)	$ 658,522,000	$ 37,691,000	$ 325,562,000	$ 295,269,000	$ 0	$ 1,195,122,000	$ 0	$ 864,462,000	$ 352,061,000	$ (21,401,000)
Beginning Balance, Shares at Dec. 31, 2009			820,152,000	505,000						31,000,000					9,000,000					3,143,000					1,121,000					1,000
Net income after dividends on preferred and preference stock	1,975,000,000	[1]				1,975,000,000			707,000,000			707,000,000		950,000,000			950,000,000		121,511,000			121,511,000		80,217,000			80,217,000
Net Income	2,040,000,000								746,000,000					967,000,000					127,714,000					81,950,000					131,309,000			131,309,000
Capital contributions from parent company									37,000,000		37,000,000			698,000,000		698,000,000			3,798,000		3,798,000			67,228,000		67,228,000			36,507,000		36,507,000
Other comprehensive income (loss)	18,000,000						18,000,000		(2,000,000)				(2,000,000)	10,000,000				10,000,000	(265,000)				(265,000)	2,000				2,000	7,382,000				7,382,000
Stock issued, shares			23,662,000																	500,000
Stock issued	772,000,000		118,000,000		654,000,000														50,000,000	50,000,000
Stock-based compensation	52,000,000				52,000,000
Cash dividends on common stock	(1,496,000,000)					(1,496,000,000)			(586,000,000)			(586,000,000)		(820,000,000)			(820,000,000)		(104,300,000)			(104,300,000)		(68,600,000)			(68,600,000)		(107,100,000)			(107,100,000)
Other, shares				31,000
Other	3,000,000			0	(1,000,000)	2,000,000																		(1,000)			(1,000)
Ending Balance at Dec. 31, 2010	16,909,000,000		4,219,000,000	(15,000,000)	3,702,000,000	8,366,000,000	(70,000,000)	707,000,000	5,393,000,000	1,222,000,000	2,156,000,000	2,022,000,000	(7,000,000)	8,741,000,000	398,000,000	5,291,000,000	3,063,000,000	(11,000,000)	1,075,036,000	303,060,000	538,375,000	236,328,000	(2,727,000)	737,368,000	37,691,000	392,790,000	306,885,000	2,000	1,263,220,000	0	900,969,000	376,270,000	(14,019,000)
Ending Balance, Shares at Dec. 31, 2010			843,814,000	474,000						31,000,000					9,000,000					3,643,000					1,121,000					1,000
Net income after dividends on preferred and preference stock	422,000,000								152,000,000					206,000,000					11,691,000					14,617,000					37,743,000
Ending Balance at Mar. 31, 2011
Beginning Balance at Dec. 31, 2010	16,909,000,000		4,219,000,000	(15,000,000)	3,702,000,000	8,366,000,000	(70,000,000)	707,000,000	5,393,000,000	1,222,000,000	2,156,000,000	2,022,000,000	(7,000,000)	8,741,000,000	398,000,000	5,291,000,000	3,063,000,000	(11,000,000)	1,075,036,000	303,060,000	538,375,000	236,328,000	(2,727,000)	737,368,000	37,691,000	392,790,000	306,885,000	2,000	1,263,220,000	0	900,969,000	376,270,000	(14,019,000)
Beginning Balance, Shares at Dec. 31, 2010			843,814,000	474,000						31,000,000					9,000,000					3,643,000					1,121,000					1,000
Net income after dividends on preferred and preference stock	2,203,000,000	[1]				2,203,000,000			708,000,000			708,000,000		1,145,000,000			1,145,000,000		105,005,000			105,005,000		94,182,000			94,182,000
Net Income	2,268,000,000								747,000,000					1,162,000,000					111,208,000					95,915,000					162,231,000			162,231,000
Capital contributions from parent company									26,000,000		26,000,000			231,000,000		231,000,000			4,334,000		4,334,000			302,065,000		302,065,000			127,241,000		127,241,000
Other comprehensive income (loss)	(41,000,000)						(41,000,000)		(11,000,000)				(11,000,000)	2,000,000				2,000,000	573,000				573,000	(8,899,000)				(8,899,000)	7,190,000				7,190,000
Stock issued, shares			21,850,000																	500,000
Stock issued	725,000,000		109,000,000		616,000,000														50,000,000	50,000,000	0
Stock-based compensation	89,000,000				89,000,000
Cash dividends on common stock	(1,601,000,000)					(1,601,000,000)			(774,000,000)			(774,000,000)		(1,096,000,000)			(1,096,000,000)		(110,000,000)			(110,000,000)		(75,500,000)			(75,500,000)		(91,200,000)			(91,200,000)
Other, shares				65,000
Other	1,000,000			(2,000,000)	3,000,000	0																		1,000			1,000
Ending Balance at Dec. 31, 2011	18,285,000,000		4,328,000,000	(17,000,000)	4,410,000,000	8,968,000,000	(111,000,000)	707,000,000	5,342,000,000	1,222,000,000	2,182,000,000	1,956,000,000	(18,000,000)	9,023,000,000	398,000,000	5,522,000,000	3,112,000,000	(9,000,000)	1,124,948,000	353,060,000	542,709,000	231,333,000	(2,154,000)	1,049,217,000	37,691,000	694,855,000	325,568,000	(8,897,000)	1,468,682,000	0	1,028,210,000	447,301,000	(6,829,000)
Ending Balance, Shares at Dec. 31, 2011			865,664,000	539,000						31,000,000					9,000,000					4,143,000					1,121,000					1,000
Beginning Balance at Sep. 30, 2011
Net income after dividends on preferred and preference stock	261,000,000								102,000,000					110,000,000					18,745,000					16,263,000					23,816,000
Ending Balance at Dec. 31, 2011	18,285,000,000							707,000,000	5,342,000,000	1,222,000,000				9,023,000,000	398,000,000				1,124,948,000					1,049,217,000	37,691,000				1,468,682,000	0
Ending Balance, Shares at Dec. 31, 2011										31,000,000					9,000,000										1,121,000					1,000
Net income after dividends on preferred and preference stock	368,000,000								126,000,000					167,000,000					20,666,000					25,255,000					29,316,000
Ending Balance at Mar. 31, 2012
Beginning Balance at Dec. 31, 2011	18,285,000,000		4,328,000,000	(17,000,000)	4,410,000,000	8,968,000,000	(111,000,000)	707,000,000	5,342,000,000	1,222,000,000	2,182,000,000	1,956,000,000	(18,000,000)	9,023,000,000	398,000,000	5,522,000,000	3,112,000,000	(9,000,000)	1,124,948,000	353,060,000	542,709,000	231,333,000	(2,154,000)	1,049,217,000	37,691,000	694,855,000	325,568,000	(8,897,000)	1,468,682,000	0	1,028,210,000	447,301,000	(6,829,000)
Beginning Balance, Shares at Dec. 31, 2011			865,664,000	539,000						31,000,000					9,000,000					4,143,000					1,121,000					1,000
Net income after dividends on preferred and preference stock	2,350,000,000	[1]				2,350,000,000			704,000,000			704,000,000		1,168,000,000			1,168,000,000		125,932,000			125,932,000		148,107,000			148,107,000
Net Income	2,415,000,000								743,000,000					1,185,000,000					132,135,000					149,840,000					175,285,000			175,285,000
Capital contributions from parent company									45,000,000		45,000,000			63,000,000		63,000,000			5,089,000		5,089,000			706,665,000		706,665,000			(662,000)		(662,000)
Other comprehensive income (loss)	(12,000,000)						(12,000,000)		(9,000,000)				(9,000,000)	2,000,000				2,000,000	573,000				573,000	184,000				184,000	6,053,000				6,053,000
Stock issued, shares			12,139,000																	400,000
Stock issued	397,000,000		61,000,000		336,000,000														40,000,000	40,000,000
Stock Repurchased During Period, Shares				(9,440,000)
Stock Repurchased During Period, Value	(430,000,000)			(430,000,000)
Stock-based compensation	106,000,000				106,000,000
Cash dividends on common stock	(1,693,000,000)					(1,693,000,000)			(684,000,000)			(684,000,000)		(983,000,000)			(983,000,000)		(115,800,000)			(115,800,000)		(106,800,000)			(106,800,000)		(127,000,000)			(127,000,000)
Other, shares				56,000
Other	1,000,000			(3,000,000)	3,000,000	1,000,000																							(1,000)			(1,000)
Ending Balance at Dec. 31, 2012	19,004,000,000		4,389,000,000	(450,000,000)	4,855,000,000	9,626,000,000	(123,000,000)	707,000,000	5,398,000,000	1,222,000,000	2,227,000,000	1,976,000,000	(27,000,000)	9,273,000,000	398,000,000	5,585,000,000	3,297,000,000	(7,000,000)	1,180,742,000	393,060,000	547,798,000	241,465,000	(1,581,000)	1,797,373,000	37,691,000	1,401,520,000	366,875,000	(8,713,000)	1,522,357,000	0	1,027,548,000	495,585,000	(776,000)
Ending Balance, Shares at Dec. 31, 2012			877,803,000	10,035,000						31,000,000					9,000,000					4,543,000					1,121,000					1,000
Beginning Balance at Sep. 30, 2012
Net income after dividends on preferred and preference stock	383,000,000								113,000,000					181,000,000					22,549,000					33,200,000					30,991,000
Ending Balance at Dec. 31, 2012	$ 19,004,000,000							$ 707,000,000	$ 5,398,000,000	$ 1,222,000,000				$ 9,273,000,000	$ 398,000,000				$ 1,180,742,000					$ 1,797,373,000	$ 37,691,000				$ 1,522,357,000	$ 0
Ending Balance, Shares at Dec. 31, 2012										31,000,000					9,000,000										1,121,000					1,000

[1] *After dividends on preferred and preference stock of subsidiaries.