Segment and Related Information - Financial Data for Business Segments (Details) (USD $)	3 Months Ended				6 Months Ended				3 Months Ended				6 Months Ended					3 Months Ended				6 Months Ended					3 Months Ended		6 Months Ended		3 Months Ended				6 Months Ended					3 Months Ended				6 Months Ended					3 Months Ended				6 Months Ended					3 Months Ended				6 Months Ended					3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013	Jun. 30, 2012		Dec. 31, 2012	Jun. 30, 2013 Electric Utilities [Member]		Jun. 30, 2012 Electric Utilities [Member]		Jun. 30, 2013 Electric Utilities [Member]		Jun. 30, 2012 Electric Utilities [Member]		Dec. 31, 2012 Electric Utilities [Member]	Jun. 30, 2013 Traditional Operating Companies [Member] Electric Utilities [Member]		Jun. 30, 2012 Traditional Operating Companies [Member] Electric Utilities [Member]		Jun. 30, 2013 Traditional Operating Companies [Member] Electric Utilities [Member]		Jun. 30, 2012 Traditional Operating Companies [Member] Electric Utilities [Member]		Dec. 31, 2012 Traditional Operating Companies [Member] Electric Utilities [Member]	Jun. 30, 2013 Southern Power [Member]	Jun. 30, 2012 Southern Power [Member]	Jun. 30, 2013 Southern Power [Member]	Jun. 30, 2012 Southern Power [Member]	Jun. 30, 2013 Southern Power [Member] Electric Utilities [Member]		Jun. 30, 2012 Southern Power [Member] Electric Utilities [Member]		Jun. 30, 2013 Southern Power [Member] Electric Utilities [Member]		Jun. 30, 2012 Southern Power [Member] Electric Utilities [Member]		Dec. 31, 2012 Southern Power [Member] Electric Utilities [Member]	Jun. 30, 2013 Eliminations [Member]		Jun. 30, 2012 Eliminations [Member]		Jun. 30, 2013 Eliminations [Member]		Jun. 30, 2012 Eliminations [Member]		Dec. 31, 2012 Eliminations [Member]	Jun. 30, 2013 Eliminations [Member] Electric Utilities [Member]		Jun. 30, 2012 Eliminations [Member] Electric Utilities [Member]		Jun. 30, 2013 Eliminations [Member] Electric Utilities [Member]		Jun. 30, 2012 Eliminations [Member] Electric Utilities [Member]		Dec. 31, 2012 Eliminations [Member] Electric Utilities [Member]	Jun. 30, 2013 All Other [Member]		Jun. 30, 2012 All Other [Member]		Jun. 30, 2013 All Other [Member]		Jun. 30, 2012 All Other [Member]		Dec. 31, 2012 All Other [Member]	Jun. 30, 2013 Kemper Igcc [Member]	Jun. 30, 2013 Kemper Igcc [Member]	Dec. 31, 2012 Kemper Igcc [Member]
Segment and Related Information (Textual) [Abstract]
Electric Utilities' Revenues	$ 4,246,000,000		$ 4,181,000,000		$ 8,143,000,000	$ 7,785,000,000			$ 4,230,000,000		$ 4,166,000,000		$ 8,116,000,000		$ 7,755,000,000			$ 4,018,000,000		$ 3,989,000,000		$ 7,687,000,000		$ 7,438,000,000			$ 89,000,000	$ 106,000,000	$ 167,000,000	$ 218,000,000	$ 307,000,000		$ 286,000,000		$ 610,000,000		$ 539,000,000			$ (22,000,000)		$ (20,000,000)		$ (46,000,000)		$ (43,000,000)			$ (95,000,000)		$ (109,000,000)		$ (181,000,000)		$ (222,000,000)			$ 38,000,000		$ 35,000,000		$ 73,000,000		$ 73,000,000
Financial data for business segments
Electric Utilities' Revenues	4,246,000,000		4,181,000,000		8,143,000,000	7,785,000,000			4,230,000,000		4,166,000,000		8,116,000,000		7,755,000,000			4,018,000,000		3,989,000,000		7,687,000,000		7,438,000,000			89,000,000	106,000,000	167,000,000	218,000,000	307,000,000		286,000,000		610,000,000		539,000,000			(22,000,000)		(20,000,000)		(46,000,000)		(43,000,000)			(95,000,000)		(109,000,000)		(181,000,000)		(222,000,000)			38,000,000		35,000,000		73,000,000		73,000,000
Segment net income (loss)	297,000,000	[1],[2]	623,000,000	[1]	378,000,000	991,000,000	[1]		296,000,000	[1],[2]	596,000,000	[1]	391,000,000	[1],[3]	964,000,000	[1]		268,000,000	[1],[2]	549,000,000	[1]	334,000,000	[1],[3]	888,000,000	[1]						28,000,000	[1],[2]	47,000,000	[1]	57,000,000	[1],[3]	76,000,000	[1]		(3,000,000)	[1],[2]	0	[1]	(1,000,000)	[1],[3]	(1,000,000)	[1]		0	[1],[2]	0	[1]	0	[1],[3]	0	[1]		4,000,000	[1],[2]	27,000,000	[1]	(12,000,000)	[1],[3]	28,000,000	[1]
Total assets	63,961,000,000				63,961,000,000			63,149,000,000	63,194,000,000				63,194,000,000				62,251,000,000	59,177,000,000				59,177,000,000				58,600,000,000					4,139,000,000				4,139,000,000				3,780,000,000	(297,000,000)				(297,000,000)				(218,000,000)	(122,000,000)				(122,000,000)				(129,000,000)	1,064,000,000				1,064,000,000				1,116,000,000
Pre-tax charge to income																																																																			450,000,000	990,000,000	540,000,000
After tax charge to income					$ 16,000,000																																																														$ 277,900,000	$ 611,300,000	$ 333,500,000

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

[2] Segment net income (loss) for the three months ended June 30, 2013 includes a $450 million pre-tax charge ($277.9 million after tax) for an estimated probable loss on the Kemper IGCC. See Note (B) under "Integrated Coal Gasification Combined Cycle – Kemper IGCC Cost Estimate" herein for additional information.

[3] Segment net income (loss) for the six months ended June 30, 2013 includes a $990 million pre-tax charge ($611.3 million after tax) for estimated probable losses on the Kemper IGCC. See Note (B) under "Integrated Coal Gasification Combined Cycle – Kemper IGCC Cost Estimate" herein for additional information.