Segment and Related Information - Financial Data for Business Segments (Details) (USD $)	3 Months Ended				9 Months Ended				3 Months Ended				9 Months Ended					3 Months Ended				9 Months Ended					3 Months Ended		9 Months Ended		3 Months Ended				9 Months Ended					3 Months Ended				9 Months Ended					3 Months Ended				9 Months Ended					3 Months Ended				9 Months Ended					3 Months Ended		9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013	Sep. 30, 2012		Dec. 31, 2012	Sep. 30, 2013 Electric Utilities [Member]		Sep. 30, 2012 Electric Utilities [Member]		Sep. 30, 2013 Electric Utilities [Member]		Sep. 30, 2012 Electric Utilities [Member]		Dec. 31, 2012 Electric Utilities [Member]	Sep. 30, 2013 Traditional Operating Companies [Member] Electric Utilities [Member]		Sep. 30, 2012 Traditional Operating Companies [Member] Electric Utilities [Member]		Sep. 30, 2013 Traditional Operating Companies [Member] Electric Utilities [Member]		Sep. 30, 2012 Traditional Operating Companies [Member] Electric Utilities [Member]		Dec. 31, 2012 Traditional Operating Companies [Member] Electric Utilities [Member]	Sep. 30, 2013 Southern Power [Member]	Sep. 30, 2012 Southern Power [Member]	Sep. 30, 2013 Southern Power [Member]	Sep. 30, 2012 Southern Power [Member]	Sep. 30, 2013 Southern Power [Member] Electric Utilities [Member]		Sep. 30, 2012 Southern Power [Member] Electric Utilities [Member]		Sep. 30, 2013 Southern Power [Member] Electric Utilities [Member]		Sep. 30, 2012 Southern Power [Member] Electric Utilities [Member]		Dec. 31, 2012 Southern Power [Member] Electric Utilities [Member]	Sep. 30, 2013 Eliminations [Member]		Sep. 30, 2012 Eliminations [Member]		Sep. 30, 2013 Eliminations [Member]		Sep. 30, 2012 Eliminations [Member]		Dec. 31, 2012 Eliminations [Member]	Sep. 30, 2013 Eliminations [Member] Electric Utilities [Member]		Sep. 30, 2012 Eliminations [Member] Electric Utilities [Member]		Sep. 30, 2013 Eliminations [Member] Electric Utilities [Member]		Sep. 30, 2012 Eliminations [Member] Electric Utilities [Member]		Dec. 31, 2012 Eliminations [Member] Electric Utilities [Member]	Sep. 30, 2013 All Other [Member]		Sep. 30, 2012 All Other [Member]		Sep. 30, 2013 All Other [Member]		Sep. 30, 2012 All Other [Member]		Dec. 31, 2012 All Other [Member]	Sep. 30, 2013 Kemper Igcc [Member]	Mar. 31, 2013 Kemper Igcc [Member]	Sep. 30, 2013 Kemper Igcc [Member]
Segment and Related Information (Textual) [Abstract]
Electric Utilities' Revenues	$ 5,017,000,000		$ 5,049,000,000		$ 13,160,000,000	$ 12,834,000,000			$ 5,005,000,000		$ 5,033,000,000		$ 13,120,000,000		$ 12,788,000,000			$ 4,744,000,000		$ 4,794,000,000		$ 12,430,000,000		$ 12,232,000,000			$ 97,000,000	$ 112,000,000	$ 264,000,000	$ 330,000,000	$ 365,000,000		$ 355,000,000		$ 975,000,000		$ 894,000,000			$ (23,000,000)		$ (20,000,000)		$ (68,000,000)		$ (63,000,000)			$ (104,000,000)		$ (116,000,000)		$ (285,000,000)		$ (338,000,000)			$ 35,000,000		$ 36,000,000		$ 108,000,000		$ 109,000,000
Financial data for business segments
Electric Utilities' Revenues	5,017,000,000		5,049,000,000		13,160,000,000	12,834,000,000			5,005,000,000		5,033,000,000		13,120,000,000		12,788,000,000			4,744,000,000		4,794,000,000		12,430,000,000		12,232,000,000			97,000,000	112,000,000	264,000,000	330,000,000	365,000,000		355,000,000		975,000,000		894,000,000			(23,000,000)		(20,000,000)		(68,000,000)		(63,000,000)			(104,000,000)		(116,000,000)		(285,000,000)		(338,000,000)			35,000,000		36,000,000		108,000,000		109,000,000
Segment net income (loss)	852,000,000	[1],[2]	976,000,000	[1]	1,230,000,000	1,967,000,000	[1]		850,000,000	[1],[2]	977,000,000	[1]	1,241,000,000	[1],[3]	1,941,000,000	[1]		765,000,000	[1],[2]	908,000,000	[1]	1,099,000,000	[1],[3]	1,797,000,000	[1]						85,000,000	[1],[2]	68,000,000	[1]	142,000,000	[1],[3]	144,000,000	[1]		3,000,000	[1],[2]	(2,000,000)	[1]	1,000,000	[1],[3]	(4,000,000)	[1]		0	[1],[2]	1,000,000	[1]	0	[1],[3]	0	[1]		(1,000,000)	[1],[2]	1,000,000	[1]	(12,000,000)	[1],[3]	30,000,000	[1]
Total assets	64,697,000,000				64,697,000,000			63,149,000,000	64,028,000,000				64,028,000,000				62,251,000,000	59,732,000,000				59,732,000,000				58,600,000,000					4,449,000,000				4,449,000,000				3,780,000,000	(421,000,000)				(421,000,000)				(218,000,000)	(153,000,000)				(153,000,000)				(129,000,000)	1,090,000,000				1,090,000,000				1,116,000,000
Pre-tax charge to income																																																																			150,000,000	540,000,000	1,100,000,000
After tax charge to income					$ 16,000,000																																																														$ 93,000,000	$ 333,500,000	$ 704,000,000

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

[2] Segment net income (loss) for the three months ended September 30, 2013 includes a $150 million pre-tax charge ($93 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 nine months ended September 30, 2013 includes $1.1 billion in pre-tax charges ($704 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.