Contingencies and Regulatory Matters (Details) (USD $)	3 Months Ended		3 Months Ended	1 Months Ended	3 Months Ended		1 Months Ended		3 Months Ended		3 Months Ended						3 Months Ended	12 Months Ended	13 Months Ended										3 Months Ended
	Mar. 31, 2012 Entity	Dec. 31, 2011	Mar. 31, 2012 Kivalina Case [Member]	Jul. 31, 2007 Alabama Power [Member]	Mar. 31, 2012 Alabama Power [Member] Coal_Fired_Generating_Facilities Claims	Dec. 31, 2011 Alabama Power [Member]	Apr. 30, 2012 Georgia Power [Member]	Jul. 31, 2007 Georgia Power [Member]	Mar. 31, 2012 Georgia Power [Member] MW Coal_Fired_Generating_Facilities Claims	Dec. 31, 2011 Georgia Power [Member]	Mar. 31, 2012 Gulf Power [Member]	Apr. 18, 2012 Gulf Power [Member]	Mar. 12, 2012 Gulf Power [Member]	Dec. 31, 2011 Gulf Power [Member]	Mar. 12, 2012 Gulf Power [Member] Minimum [Member]	Mar. 12, 2012 Gulf Power [Member] Maximum [Member]	Mar. 31, 2012 Mississippi Power [Member]	Dec. 31, 2009 Mississippi Power [Member]	Apr. 30, 2012 Mississippi Power [Member]	Feb. 14, 2012 Mississippi Power [Member]	Feb. 02, 2012 Mississippi Power [Member]	Dec. 31, 2011 Mississippi Power [Member]	May 26, 2010 Mississippi Power [Member]	Mar. 31, 2012 Mississippi Power [Member] MRA Revenue [Member]	Dec. 31, 2011 Mississippi Power [Member] MRA Revenue [Member]	Mar. 31, 2012 Mississippi Power [Member] MB Revenue [Member]	Dec. 31, 2011 Mississippi Power [Member] MB Revenue [Member]	Mar. 31, 2012 Gulf Power and Mississippi Power [Member]	Mar. 31, 2012 Electricity Generation Plant, Non-Nuclear [Member] Mississippi Power [Member]	Mar. 31, 2012 Mine [Member] Mississippi Power [Member]
Contingencies and Regulatory Matters (Textual) [Abstract]
Number of coal fired generating facilities at which new source review violations occurred					5				3
Number of dismissed claims against Subsidiary					5
Total Number of Claims					8
Claims left for summary disposition or trial against Alabama Power					3
Environmental remediation liability									$ 20,000,000		$ 60,000,000
Damages from lost property values and relocating village cost, lower range			95,000,000
Civil penalties per violation rate									37,500
Number of times of punitive damages in comparison to cost incurred by Environmental Protection Agency									3
Other deferred credits and liabilities	15,725,000,000	15,383,000,000			5,419,000,000	5,326,000,000			6,833,000,000	6,703,000,000	1,093,069,000			1,021,743,000			816,133,000					776,781,000
Claims awarded to companies related to nuclear fuel disposal litigation				17,000,000				30,000,000
Damages awarded							27,000,000
Increase in base rate under cost based electric tariff due to settlement																	22,600,000
Revised rate period																	12 months
Revenue to be received from increase in base rate																	17,000,000
Percentage of increase in annual revenue																				0.30%
Amount approved for property damage reserve																					3,700,000
Amount of over recovered retail fuel costs included in the balance sheets																	50,900,000					42,400,000
Amount of over recovered fuel costs																								18,100,000	14,300,000	2,400,000	2,200,000
Amount of over recovered MRA emissions allowance cost included in the balance sheets																	1,700,000					1,700,000
Deferred cost related to construction																	5,000,000
Grant funds receivable during construction																	245,300,000
Portion of deferred construction cost under review																	46,000,000
Reduction in projected in-service cost due to recovered cost									4,400,000,000
Percentage decrease in fuel rates requested with Georgia Public Service Commission									19.00%
Under recovered energy conservation costs											2,000,000			3,100,000
Electric generating capacity in Mega Watts under consortium agreement									1,100
Recovery of project financing cost as per Legislation									1,700,000,000
Total certified cost									6,100,000,000
Over recovered fuel cost balance									22,000,000
Under recovered regulatory clause revenues	5,000,000	143,000,000								137,000,000	4,536,000			5,530,000
Over recovered purchased power capacity costs											9,600,000			8,000,000
Over recovered environmental cost.											4,000,000			10,000,000
Amount of government construction cost incentive received																							296,000,000
Maximum cap construction cost																	2,880,000,000
Cost incurred for use of mine																	79,700,000
Term of management fee contract with liberty fuels company																														40 years
Tax credits (Phase I)																		133,000,000
Tax credit (Phase II)																			279,000,000
Minimum percentage of carbon dioxide that must be capture and sequester to remain eligible for the phase II tax credits																	65.00%
Received or accrued tax benefits related to Tax credit																	141,100,000
Percentage of bonus tax																	100.00%
Amount of credit not available till future period																	105,000,000
Carry forward period of tax credit																	20 years
Percentage interest acquired under asset purchase agreement																	17.50%
Percentage interest transferred under asset purchase agreement																	17.50%
Deposit received																	150,000,000
Maximum period to refund deposit upon termination of asset purchase agreement																	60 days
Estimated cost																													2,400,000,000
Percentage of financing costs of construction work in progress																							100.00%
Cost deferred in other regulatory assets	3,486,000,000	3,532,000,000			995,000,000	994,000,000			1,562,000,000	1,604,000,000	316,519,000			323,116,000			190,894,000					185,694,000
Other deferred charges and assets	451,000,000	481,000,000			161,000,000	186,000,000			203,000,000	187,000,000	29,433,000			39,493,000			30,422,000					28,674,000
Capacity of units include application request by Georgia Power that country PSC certify purchase from four PPAs selected through 2015 request for proposal process									998
Retail rate of return on common equity															9.25%	11.25%
Estimated cost of scrubber project																	330,000,000											660,000,000
Ownership percentage in Scrubber project											50.00%						50.00%
Expected decrease in annual billings for fuel costs									567,000,000
Scrubber project expenditures amount																	27,800,000											55,600,000
Cost deferred in other regulatory assets																	22,900,000
Previously expensed																	1,000,000
Amortization to earnings of financing costs capitalized over the five year period									91,000,000
Costs included in CWIP									68,000,000								1,280,000,000
Consortium provided initial estimate of proposed adjustment to contract price									400,000,000
Damages from lost property values and relocating village cost, upper range			400,000,000
Increase in retail rates and charges													64,000,000
Previously approved interim retail rate increase													38,500,000
Average retail rate of return on common equity											10.25%
Increase in retail rates and charges in next fiscal year											4,000,000
Increase in rates due to motion grant												2,000,000
Over Recovered Fuel Cost											28,800,000			9,900,000
Estimated capital cost of mine																	245,000,000
Cost incurred by Mississippi Power associated with plant including regulatory filing costs																	1,300,000,000
Costs associated with CCP12 grant funds																	245,300,000
Other deferred charges and assets																	2,300,000
Contingencies and Regulatory Matters (Additional Textual) [Abstract]
Civil penalties under Clean Air Act per day, lower range	25,000
Civil penalties under Clean Air Act per day, upper range	37,500
Number of entities received notice from TCEQ requesting their participation in anticipated site redemption	100
Damages from lost property values and relocating village cost, lower range			$ 95,000,000