Joint Ownership Agreements (Details) (USD $)								12 Months Ended					12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Southern Power [Member] MW	Dec. 31, 2012 Mississippi Power [Member]	Dec. 31, 2011 Mississippi Power [Member]	Dec. 31, 2012 Georgia Power [Member]	Dec. 31, 2011 Georgia Power [Member]	Dec. 31, 2012 Alabama Power [Member] MW	Dec. 31, 2011 Alabama Power [Member]	Dec. 31, 2010 Alabama Power [Member]	Dec. 31, 2012 Gulf Power [Member]	Dec. 31, 2011 Gulf Power [Member]	Dec. 31, 2012 Southern Electric Generating Company [Member] Georgia Power [Member]	Dec. 31, 2011 Southern Electric Generating Company [Member] Georgia Power [Member]	Dec. 31, 2010 Southern Electric Generating Company [Member] Georgia Power [Member] Purchased power from affiliates [Member]	Dec. 31, 2012 Southern Electric Generating Company [Member] Alabama Power [Member] MW	Dec. 31, 2011 Southern Electric Generating Company [Member] Alabama Power [Member]	Dec. 31, 2010 Southern Electric Generating Company [Member] Alabama Power [Member]	Dec. 31, 2012 Plant Vogtle Nuclear Units One and Two [Member]	Dec. 31, 2012 Plant Vogtle Nuclear Units One and Two [Member] Georgia Power [Member]	Dec. 31, 2012 Alabama Power [Member] Georgia Power [Member] MW	Dec. 31, 2012 Greene County [Member] Alabama Power [Member] MW		Dec. 31, 2012 Greene County [Member] Alabama Power [Member] Mississippi Power [Member] MW	Dec. 31, 2012 Greene County [Member] Alabama Power [Member]	Dec. 31, 2012 Plant Hatch (nuclear) [Member]	Dec. 31, 2012 Plant Hatch (nuclear) [Member] Georgia Power [Member]	Dec. 31, 2012 Plant Miller (coal) Units 1 and 2 [Member]	Dec. 31, 2012 Plant Miller (coal) Units 1 and 2 [Member] Alabama Power [Member] MW		Dec. 31, 2012 Plant Scherer (coal) Units 1 and 2 [Member]	Dec. 31, 2012 Plant Scherer (coal) Units 1 and 2 [Member] Georgia Power [Member]	Dec. 31, 2012 Plant Wansley Coal [Member]	Dec. 31, 2012 Plant Wansley Coal [Member] Georgia Power [Member]	Dec. 31, 2012 Rocky Mountain (pumped storage) [Member]	Dec. 31, 2012 Rocky Mountain (pumped storage) [Member] Georgia Power [Member]	Dec. 31, 2012 Intercession City (combustion turbine) [Member]	Dec. 31, 2012 Intercession City (combustion turbine) [Member] Georgia Power [Member]	Dec. 31, 2012 Plant Stanton (combined cycle) Unit A [Member]	Dec. 31, 2012 Plant Stanton (combined cycle) Unit A [Member] Southern Power [Member]	Dec. 31, 2012 Vogtle Units 3 and 4 [Member] Georgia Power [Member]	Jul. 31, 2010 Plant Daniel Units 1 and 2 [Member] Mississippi Power [Member]	Dec. 31, 2012 Plant Daniel Units 1 and 2 [Member] Gulf Power [Member] MW		Dec. 31, 2012 Plant Daniel Units 1 and 2 [Member] Gulf Power [Member] Mississippi Power [Member] MW	Dec. 31, 2012 Plant Scherer Unit 3 [Member] Georgia Power [Member]	Dec. 31, 2012 Plant Scherer Unit 3 [Member] Gulf Power [Member] MW		Dec. 31, 2012 Southern Power [Member] Plant Stanton (combined cycle) Unit A [Member]	Dec. 31, 2012 Orlando Utilities Commission [Member] Plant Stanton (combined cycle) Unit A [Member] Southern Power [Member]	Dec. 31, 2012 Florida Municipal Power Agency [Member] Plant Stanton (combined cycle) Unit A [Member] Southern Power [Member]	Dec. 31, 2012 Kissimmee Utility Authority [Member] Plant Stanton (combined cycle) Unit A [Member] Southern Power [Member]	Dec. 31, 2012 Natural Gas Pipeline [Member] Alabama Power [Member]
Jointly owned utility plant interests
Total Megawatt Capacity			659					1,000								1,020					1,020	500		500	500				1,320														1,000		1,000		818
Percent ownership								14.00%			50.00%								45.70%	45.70%		60.00%	[1]	40.00%	86.00%	50.10%	50.10%	91.80%	91.84%	[2]	8.40%	8.40%	53.50%	53.50%	25.40%	25.40%	33.30%	33.30%	65.00%		45.70%	50.00%	50.00%		50.00%	75.00%	25.00%		65.00%	28.00%	3.50%	3.50%
Amount of Investment																			$ 3,327,000,000	$ 3,327,000,000		$ 151,000,000		$ 89,474,000		$ 1,037,000,000	$ 1,037,000,000	$ 1,401,000,000	$ 1,401,000,000		$ 161,000,000	$ 161,000,000	$ 801,000,000	$ 801,000,000	$ 181,000,000	$ 181,000,000	$ 12,000,000	$ 12,000,000	$ 156,000,000	$ 155,800,000			$ 277,440,000	[3]	$ 293,451,000	$ 1,127,000,000	$ 373,576,000	[3]
Accumulated Depreciation																			1,996,000,000	1,996,000,000		89,000,000		45,402,000		551,000,000	551,000,000	551,000,000	551,000,000		78,000,000	78,000,000	240,000,000	240,000,000	116,000,000	116,000,000	4,000,000	4,000,000	36,000,000	36,300,000			165,120,000		147,833,000	387,000,000	117,181,000
Plant acquisition adjustment	124,000,000	124,000,000		81,412,000	81,408,000	28,000,000	28,000,000	12,000,000	12,000,000		2,286,000	2,542,000																																			2,300,000
Share Of Purchased Power													107,000,000	141,000,000	100,000,000	109,000,000	142,000,000	101,000,000
Joint Ownership Agreements (Textual) [Abstract]
Unconditional guarantee to pay outstanding pollution control revenue bond principal																25,000,000
Guarantee of unsecured senior notes																50,000,000
Jointly Owned Affiliate Equity								82,000,000
Jointly Owned Affiliate Long Term Debt								75,000,000
Jointly Owned Affiliate Long Term Debt Annual Interest Requirement								3,000,000
Short-term Debt, Maximum Amount Outstanding During Period								45,000,000
Dividends paid by equity method investment								14,000,000	15,000,000	5,000,000
Ownership percentage, equity method investment								50.00%
Construction work in progress																			$ 0	$ 67,000,000		$ 9,000,000		$ 4,386,000		$ 0	$ 49,000,000	$ 0	$ 8,000,000		$ 0	$ 77,000,000	$ 0	$ 8,000,000	$ 0	$ 0	$ 0	$ 1,000,000	$ 0				$ 69,774,000		$ 73,534,000	$ 28,000,000	$ 8,763,000						$ 100,000

[1] Jointly owned with an affiliate, Mississippi Power.

[2] Jointly owned with PowerSouth.

[3] Includes net plant acquisition adjustment of $2.3 million.