Segment and Related Information - Financial Data for Business Segments and Products and Services (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2012 entities	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012 entities		Dec. 31, 2011		Dec. 31, 2010
Segment Reporting Information [Line Items]
Number of Traditional Operating Companies	4								4
Financial data for business segments
Operating revenues	$ 3,703,000,000	$ 5,049,000,000	$ 4,181,000,000	$ 3,604,000,000	$ 3,696,000,000	$ 5,428,000,000	$ 4,521,000,000	$ 4,012,000,000	$ 16,537,000,000		$ 17,657,000,000		$ 17,456,000,000
Depreciation and amortization									1,787,000,000		1,717,000,000		1,513,000,000
Interest income									40,000,000		21,000,000		24,000,000
Interest expense									859,000,000		857,000,000		895,000,000
Income taxes									1,334,000,000		1,219,000,000		1,026,000,000
Consolidated Net Income After Dividends on Preferred and Preference Stock	383,000,000	976,000,000	623,000,000	368,000,000	261,000,000	916,000,000	604,000,000	422,000,000	2,350,000,000	[1]	2,203,000,000	[1]	1,975,000,000	[1]
Total Assets	63,149,000,000				59,267,000,000				63,149,000,000		59,267,000,000		55,032,000,000
Gross property additions									5,059,000,000		4,853,000,000		4,443,000,000
Electric Utilities [Member]
Financial data for business segments
Operating revenues									16,478,000,000		17,587,000,000		17,374,000,000
Depreciation and amortization									1,772,000,000		1,700,000,000		1,495,000,000
Interest income									22,000,000		19,000,000		22,000,000
Interest expense									820,000,000		803,000,000		833,000,000
Income taxes									1,400,000,000		1,293,000,000		1,114,000,000
Consolidated Net Income After Dividends on Preferred and Preference Stock									2,321,000,000	[1]	2,214,000,000	[1]	1,991,000,000	[1]
Total Assets	62,251,000,000				58,076,000,000				62,251,000,000		58,076,000,000		54,454,000,000
Gross property additions									5,054,000,000		4,844,000,000		4,434,000,000
Traditional Operating Companies [Member] | Electric Utilities [Member]
Financial data for business segments
Operating revenues									15,730,000,000		16,763,000,000		16,712,000,000
Depreciation and amortization									1,629,000,000		1,576,000,000		1,376,000,000
Interest income									21,000,000		18,000,000		22,000,000
Interest expense									757,000,000		726,000,000		757,000,000
Income taxes									1,307,000,000		1,217,000,000		1,039,000,000
Consolidated Net Income After Dividends on Preferred and Preference Stock									2,145,000,000	[1]	2,052,000,000	[1]	1,860,000,000	[1]
Total Assets	58,600,000,000				54,622,000,000				58,600,000,000		54,622,000,000		51,144,000,000
Gross property additions									4,813,000,000		4,589,000,000		4,029,000,000
Southern Power [Member]
Segment and Related Information (Textual) [Abstract]
Southern Power's revenues from sales to the traditional operating companies									425,000,000		359,000,000		371,000,000
Southern Power [Member] | Electric Utilities [Member]
Financial data for business segments
Operating revenues									1,186,000,000		1,236,000,000		1,130,000,000
Depreciation and amortization									143,000,000		124,000,000		119,000,000
Interest income									1,000,000		1,000,000		0
Interest expense									63,000,000		77,000,000		76,000,000
Income taxes									93,000,000		76,000,000		75,000,000
Consolidated Net Income After Dividends on Preferred and Preference Stock									175,000,000	[1]	162,000,000	[1]	131,000,000	[1]
Total Assets	3,780,000,000				3,581,000,000				3,780,000,000		3,581,000,000		3,438,000,000
Gross property additions									241,000,000		255,000,000		405,000,000
Eliminations [Member]
Financial data for business segments
Operating revenues									(82,000,000)		(79,000,000)		(80,000,000)
Depreciation and amortization									0		1,000,000		0
Interest income									(1,000,000)		(1,000,000)		(1,000,000)
Interest expense									0		0		(1,000,000)
Income taxes									0		0		1,000,000
Consolidated Net Income After Dividends on Preferred and Preference Stock									(4,000,000)	[1]	(3,000,000)	[1]	(5,000,000)	[1]
Total Assets	(218,000,000)				(401,000,000)				(218,000,000)		(401,000,000)		(600,000,000)
Gross property additions									0		0		0
Eliminations [Member] | Electric Utilities [Member]
Financial data for business segments
Operating revenues									(438,000,000)		(412,000,000)		(468,000,000)
Depreciation and amortization									0		0		0
Interest income									0		0		0
Interest expense									0		0		0
Income taxes									0		0		0
Consolidated Net Income After Dividends on Preferred and Preference Stock									1,000,000	[1]	0	[1]	0	[1]
Total Assets	(129,000,000)				(127,000,000)				(129,000,000)		(127,000,000)		(128,000,000)
Gross property additions									0		0		0
All Other [Member]
Financial data for business segments
Operating revenues									141,000,000		149,000,000		162,000,000
Depreciation and amortization									15,000,000		16,000,000		18,000,000
Interest income									19,000,000		3,000,000		3,000,000
Interest expense									39,000,000		54,000,000		63,000,000
Income taxes									(66,000,000)		(74,000,000)		(89,000,000)
Consolidated Net Income After Dividends on Preferred and Preference Stock									33,000,000	[1]	(8,000,000)	[1]	(11,000,000)	[1]
Total Assets	1,116,000,000				1,592,000,000				1,116,000,000		1,592,000,000		1,178,000,000
Gross property additions									$ 5,000,000		$ 9,000,000		$ 9,000,000

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