Contingencies and Regulatory Matters (Details Textual) (USD $)	1 Months Ended		9 Months Ended	1 Months Ended		6 Months Ended	9 Months Ended	1 Months Ended	9 Months Ended					9 Months Ended		1 Months Ended		9 Months Ended	12 Months Ended									9 Months Ended		9 Months Ended
	Apr. 30, 2009 Potentially_Responsible_Party	Jul. 31, 2004 Other_Power_Companies Environmental_Groups	Sep. 30, 2011	Sep. 30, 2010 Alabama Power [Member] Claims	Jul. 31, 2007 Alabama Power [Member]	Jun. 30, 2011 Alabama Power [Member]	Sep. 30, 2011 Alabama Power [Member] Coal_Fired_Generating_Facilities	Jul. 31, 2007 Georgia Power [Member]	Sep. 30, 2011 Georgia Power [Member] Megawatt Million_British_Thermal_Unit	Aug. 26, 2011 Georgia Power [Member]	Aug. 16, 2011 Georgia Power [Member]	Jun. 10, 2011 Georgia Power [Member]	May 24, 2011 Georgia Power [Member]	Sep. 30, 2011 Gulf Power [Member]	Jul. 08, 2011 Gulf Power [Member]	Nov. 30, 2010 Mississippi Power [Member]	May 31, 2009 Mississippi Power [Member]	Sep. 30, 2011 Mississippi Power [Member]	Dec. 31, 2008 Mississippi Power [Member]	Oct. 19, 2011 Mississippi Power [Member]	Sep. 09, 2011 Mississippi Power [Member] mi	May 05, 2011 Mississippi Power [Member]	Apr. 19, 2011 Mississippi Power [Member]	Mar. 04, 2011 Mississippi Power [Member]	Jan. 31, 2011 Mississippi Power [Member]	Dec. 31, 2010 Mississippi Power [Member]	Aug. 19, 2010 Mississippi Power [Member]	Sep. 30, 2011 Mississippi Power [Member] MRA Revenue [Member]	Dec. 31, 2010 Mississippi Power [Member] MRA Revenue [Member]	Sep. 30, 2011 Mississippi Power [Member] MB Revenue [Member]	Dec. 31, 2010 Mississippi Power [Member] MB Revenue [Member]	Sep. 30, 2011 Gulf Power and Mississippi Power [Member]	Sep. 30, 2011 Southern Company and Gulf Power [Member]	Dec. 31, 2010 Southern Company and Gulf Power [Member]	Sep. 30, 2011 Southern Company and Alabama Power [Member]	Dec. 31, 2010 Southern Company and Alabama Power [Member]
Contingencies and Regulatory Matters (Textual) [Abstract]
Number of coal fired generating facilities at which new source review violations occurred							8
Number of dismissed claims against Alabama Power				5
Total Number of Claims				8
Claims left for summary disposition or trial against Alabama Power				3
Civil penalties under Clean Air Act per day, lower range			$ 25,000
Civil penalties under Clean Air Act per day, upper range			37,500
No. of environmental group which filed complaint against the Southern Company		3
Number other electric power companies against which complaint is filed		4
Damages from lost property values and relocating village cost, lower range			95,000,000
Damages from lost property values and relocating village cost, upper range			400,000,000
Environmental remediation liability									14,000,000					62,000,000
Number of PRPs filed separate actions	2
Agreements with plaintiffs in pending actions (in percentage)																		95.00%
Civil penalties per violation rate									37,500
Claims awarded to companies related to nuclear fuel disposal litigation					17,000,000			30,000,000
Unrecognized tax benefits of additional tax benefits recorded												64,000,000
Related regulatory liability												62,000,000
Reduction in related interest expense												23,000,000
Anticipates of elimination adjustment will result in additional revenues							30,000,000
Anticipates of elimination adjustment will result in additional revenues with an annual effect							150,000,000
Capacity of units used by Georgia Power to control fuel switch or retire remaining fossil generating units where environmental controls not yet install									2,600
Capacity of units used by Georgia Power more likely than others to switch fuel or control in time to comply with utility MACT Rule									600
Currently available capacity of unit not rely by Georgia Power in 2015									2,000
Capacity of units include application request by Georgia Power that country PSC certify purchase from four PPAs selected through 2015 request for proposal process									1,562
Estimated cost of scrubber project																		312,500,000														625,000,000
Scrubber project expenditures amount																		17,900,000														35,800,000
Ownership percentage in Scrubber project														50.00%				50.00%
Condition for adjustment to the fuel cost recovery														If the projected fuel cost over or under recovery balance at year-end exceeds 10% of the projected fuel revenue applicable for the period, Gulf Power is required to notify the Florida PSC and indicate if an adjustment to the fuel cost recovery factor is being requested.
Under recovered fuel cost																																	7,500,000	17,400,000	39,000,000	4,000,000
Condition for adjustment to purchased power capacity recovery														If the projected purchased power capacity cost over or under recovery balance at year-end exceeds 10% of the projected purchased power capacity revenue applicable for the period, Gulf Power is required to notify the Florida PSC and indicate an adjustment to the purchased power capacity cost recovery factor is being requested.
Over recovered purchased power capacity costs																																	3,500,000	4,400,000
Approved amount for scrubber project																						19,500,000
Over recovered environmental cost																																	16,900,000	10,400,000
Amount approved for property damage reserve																									3,600,000
Increase (decrease) in annual revenues																		900,000
Percentage decrease in prior year annual retail revenue amount due to retail fuel cost recovery factor																		5.00%
Amount of over recovered retail fuel costs included in the balance sheets																		41,400,000								55,200,000
Amount of over recovered MRA emissions allowance cost included in the balance sheets																		1,000,000
Estimated cost associated with repairing damage facility to operation and maintenance expenses						45,000,000
Estimated cost associated with repairing damage facility to capital expenditure						163,000,000
Accumulated NDR reserve reflected as other regulatory liabilities, deferred																																			75,000,000
Establishment period														5 years
Conservation goals covering period														10 years
Percentage rate increase																1.936%
Rate increase amount																16,100,000
Percentage decrease in fuel rates requested with Georgia Public Service Commission													0.61%
Expected decrease in annual billings for fuel costs													43,000,000
Cost deferred in other regulatory assets																		19,000,000
Previously expensed																		1,000,000
Construction and capital costs included in semi-annual construction monitoring report made on Plant Vogtle Units 3 and 4											1,300,000,000
Projected financing costs to recover due to legislation									1,700,000,000
Reduction in projected in-service cost									4,400,000,000
Amortization to earnings of financing costs capitalized over the five year period									91,000,000
Costs included in CWIP									78,000,000									463,800,000
Expected Number of Days for the Issuance of Construction and Operating Licenses by the NRC staff									10 days
Approval pending in percentage to increase current certified amount										4.60%
Generate additional gross annual revenues														38,500,000
Retail rate of return on common equity															11.70%
Generate additional gross annual revenues															93,500,000
Tax credits (Phase I)																	133,000,000
Tax credits (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%
Accrued tax benefits on tax credits																		73,900,000
Agreement reached to assign the remaining funds to the Kemper IGCC																			270,000,000
Grant funds assigned to receive during initial operations of plant																											25,000,000
Grant funds assigned to receive during construction of plant																			245,000,000
Grant received for plant																		158,600,000
Additional billed grant for plant																				20,900,000
Percentage of Carbon dioxide captured from project by purchase Denbury																								70.00%
Percentage of contract to purchase carbon dioxide from Kemper IGCC																								30.00%
New Co2 Pipeline Infrastructure																					61
Estimated cost of pipeline infrastructure																					141,000,000
Estimated capital cost of mine																					245,000,000
Cost incurred by Mississippi Power associated with plant including regulatory filing costs																		664,900,000
Costs associated with CCP12 grant funds																		179,500,000
Other deferred charges and assets																		1,600,000
Cash Payment to be Made in Conjunction with Purchase of Facility																		85,000,000
Fixed stated interest rate of debt obligation																		7.13%
Percentage annual decrease in revenue amount due to decrease in wholesale fuel rate																												3.50%		7.00%
Amount of over recovered fuel costs																												14,600,000	17,500,000	2,300,000	4,400,000
Fair value of debt assumed in Plant Daniel Combined Cycle Generating Units																		346,000,000
Amount of Facility reflected in Southern Company and Mississippi Power financial statements																		431,000,000
Lesser obligation related to aggregate principal amount			$ 270,000,000