Contingencies and Regulatory Matters - Textual (Details) (USD $)	12 Months Ended					1 Months Ended			3 Months Ended			6 Months Ended	12 Months Ended				12 Months Ended	0 Months Ended	1 Months Ended		3 Months Ended	12 Months Ended														0 Months Ended	1 Months Ended	12 Months Ended																							0 Months Ended			12 Months Ended				12 Months Ended		12 Months Ended		12 Months Ended	0 Months Ended	12 Months Ended																				12 Months Ended			12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Jun. 14, 2012	Apr. 30, 2011 Alabama Power [Member]	Sep. 30, 2010 Alabama Power [Member] Claim	Jul. 31, 2007 Alabama Power [Member]	Jun. 30, 2012 Alabama Power [Member]	Dec. 31, 2011 Alabama Power [Member]	Sep. 30, 2011 Alabama Power [Member]	Jun. 30, 2011 Alabama Power [Member]	Dec. 31, 2012 Alabama Power [Member] Property	Dec. 31, 2011 Alabama Power [Member]	Dec. 31, 1999 Alabama Power [Member] Facility	Sep. 17, 2012 Alabama Power [Member] MW	Dec. 31, 2012 Southern Power [Member]	Jan. 02, 2011 Georgia Power [Member]	Mar. 31, 2012 Georgia Power [Member] MW	Jul. 31, 2007 Georgia Power [Member]	Mar. 31, 2012 Georgia Power [Member] MW	Dec. 31, 2012 Georgia Power [Member] MW Claim	Dec. 31, 2011 Georgia Power [Member]	Dec. 31, 2010 Georgia Power [Member]	Dec. 31, 2009 Georgia Power [Member]	Dec. 31, 2008 Georgia Power [Member] MW	Dec. 31, 1999 Georgia Power [Member] Facility	Jan. 02, 2013 Georgia Power [Member]	Jun. 01, 2012 Georgia Power [Member]	Apr. 02, 2012 Georgia Power [Member]	Jan. 02, 2012 Georgia Power [Member]	Jun. 01, 2011 Georgia Power [Member]	Dec. 31, 2012 Georgia Power [Member] Plant Branch One And Two [Member]	Dec. 31, 2012 Georgia Power [Member] Plant Branch [Member]	Dec. 31, 2012 Georgia Power [Member] Maximum [Member] MW	Apr. 02, 2012 Mississippi Power [Member]	May 31, 2010 Mississippi Power [Member] MW	Dec. 31, 2012 Mississippi Power [Member]	Dec. 31, 2010 Mississippi Power [Member] Claim	Dec. 31, 2009 Mississippi Power [Member]	Dec. 31, 2001 Mississippi Power [Member]	Jan. 18, 2013 Mississippi Power [Member]	Jun. 14, 2012 Mississippi Power [Member]	Feb. 14, 2012 Mississippi Power [Member]	Feb. 02, 2012 Mississippi Power [Member]	Dec. 31, 2011 Mississippi Power [Member]	Nov. 15, 2011 Mississippi Power [Member]	Nov. 02, 2011 Mississippi Power [Member]	Sep. 30, 2011 Mississippi Power [Member] mi	May 31, 2011 Mississippi Power [Member]	Apr. 19, 2011 Mississippi Power [Member]	Mar. 31, 2011 Mississippi Power [Member]	Jan. 31, 2011 Mississippi Power [Member]	Nov. 30, 2010 Mississippi Power [Member]	Jul. 31, 2010 Mississippi Power [Member]	Jul. 27, 2010 Mississippi Power [Member]	Jul. 31, 2010 Mississippi Power [Member] Plant Daniel Units 1 and 2 [Member]	Jun. 14, 2012 Mississippi Power [Member] Minimum [Member]	Dec. 31, 2012 Mississippi Power [Member] Maximum [Member]	Jun. 14, 2012 Mississippi Power [Member] Maximum [Member]	Nov. 05, 2012 Gulf Power [Member] kWh	Jun. 19, 2012 Gulf Power [Member] kWh	Feb. 14, 2012 Gulf Power [Member] kWh	Dec. 31, 2012 Gulf Power [Member]	Mar. 12, 2012 Gulf Power [Member]	Aug. 23, 2011 Gulf Power [Member]	Dec. 31, 2012 Gulf Power [Member] Plant Daniel Units 1 and 2 [Member]	Dec. 31, 2012 Gulf Power [Member] Minimum [Member]	Mar. 12, 2012 Gulf Power [Member] Minimum [Member]	Dec. 31, 2012 Gulf Power [Member] Maximum [Member]	Mar. 12, 2012 Gulf Power [Member] Maximum [Member]	Dec. 31, 2012 Plant Boulevard [Member] Georgia Power [Member] MW	Oct. 20, 2011 Plant Daniel Units Three and Four [Member] Mississippi Power [Member]	Dec. 31, 2012 Electricity Generation Plant, Non-Nuclear [Member] Mississippi Power [Member]	Dec. 31, 2012 Mine [Member] Mississippi Power [Member]	Dec. 31, 2012 Plant Branch [Member] Georgia Power [Member] MW	Dec. 31, 2012 Plant Yates [Member] Georgia Power [Member] MW	Dec. 31, 2012 Plant McManus [Member] Georgia Power [Member] MW	Dec. 31, 2012 Plant Kraft [Member] Georgia Power [Member] MW	Dec. 31, 2012 Plant Bowen [Member] Georgia Power [Member] MW	Dec. 31, 2012 Environmental Issue [Member] Minimum [Member]	Dec. 31, 2012 Environmental Issue [Member] Maximum [Member]	Dec. 31, 2012 Environmental Issue [Member] Alabama Power [Member] Minimum [Member]	Dec. 31, 2012 Environmental Issue [Member] Alabama Power [Member] Maximum [Member]	Dec. 31, 2012 Environmental Issue [Member] Georgia Power [Member] Minimum [Member]	Dec. 31, 2012 Environmental Issue [Member] Georgia Power [Member] Maximum [Member]	Dec. 31, 2012 Deferred Under Recovered Regulatory cCause Revenue [Member] Alabama Power [Member]	Dec. 31, 2012 Under Recovered Regulatory Clause Revenues and Other Current Liabilities [Member] Gulf Power [Member]	Dec. 31, 2012 Other Regulatory Assets, Deferred and Other Deferred Credits and Liabilities [Member] Gulf Power [Member]	Dec. 31, 2012 Other regulatory liabilities, current [Member] Gulf Power [Member]	Dec. 31, 2011 Other regulatory liabilities, current [Member] Gulf Power [Member]	Dec. 31, 2012 Under recovered regulatory clause revenues [Member] Alabama Power [Member]	Dec. 31, 2012 Under recovered regulatory clause revenues [Member] Gulf Power [Member]	Dec. 31, 2012 Retail [Member] Mississippi Power [Member]	Dec. 31, 2011 MRA Revenue [Member] Mississippi Power [Member]	Dec. 31, 2012 MRA Revenue [Member] Mississippi Power [Member]	Dec. 31, 2011 MB Revenue [Member] Mississippi Power [Member]	Dec. 31, 2012 MB Revenue [Member] Mississippi Power [Member]	Dec. 31, 2012 Hurricane [Member] Mississippi Power [Member]	Sep. 30, 2010 Mississippi Power [Member] Alabama Power [Member] Claim	Jan. 02, 2013 Subsequent Event [Member] Georgia Power [Member]	Dec. 31, 2012 Storm Costs [Member] Georgia Power [Member]
Loss Contingencies [Line Items]
Construction And Capital Costs Included In Semi Annual Construction Monitoring Report																						$ 2,000,000,000
Additional Construction Capital Costs																						200,000,000
Increase (Decrease) In Projected Certified Construction Capital Costs																						5.00%
Estimated In-service Capital Cost																						4,800,000,000
Financing Costs During Construction Period																						2,000,000,000
Gain (Loss) Related to Litigation Settlement	19,000,000	0	0	(202,000,000)
Amount of Insurance Claim Received in Respect of Litigation Settlement					25,000,000
Legal Fee Related to Insurance Recoveries					6,000,000
Net Amount Received of Insurance Claim in Respect of Litigation Settlement					19,000,000
Maximum Period of Discretion																																						15 days
Environmental Matters [Abstract]
Number of coal fired generating facilities at which new source review violations occurred															5												3
Number of dismissed claims							5																																5
Total number of claims							8																																8
Claims left for summary disposition or trial							3																																3																																																													1
Civil penalties under Clean Air Act per day, lower range	25,000												25,000									25,000																25,000																										25,000
Civil penalties under Clean Air Act per day, upper range	37,500												37,500									37,500																37,500																										37,500
Loss contingency, damages sought, lower limit																	95,000,000																					95,000,000																										95,000,000																	95,000,000		95,000,000		95,000,000
Loss contingency, damages sought, upper limit																	400,000,000																					400,000,000																										400,000,000																		400,000,000		400,000,000		400,000,000
Civil penalties per violation rate																						37,500
Number of times of punitive damages in comparison to cost incurred by Environmental Protection Agency																						3
Environmental remediation liability																						19,000,000																																										60,500,000																								2,600,000	57,900,000
FERC Matters [Abstract]
Increase in annual base wholesale revenues																																				22,600,000												32,000,000
Period over which annual revenue will increase under tariff																																				12 months
Operating lease, initial term																																						10 years			10 years																																10 years
Estimated remaining useful life of plant																																																																									P30Y
Nuclear Fuel Disposal Costs [Abstract]
Claims awarded to companies related to nuclear fuel disposal litigation								17,000,000												27,000,000
Income Tax Matters [Abstract]
Related regulatory liability																							62,000,000
Retail Regulatory Matters [Abstract]
Anticipates of elimination adjustment will result in additional revenues										31,000,000			106,000,000
Rate Adjustment Period													2 years
Maximum percentage of Rate RSE													4.00%
Maximum annual percentage of ratio rate													5.00%
Minimum projected retail return on common equity at which retail rates remain unchanged													13.00%
Maximum projected retail return on common equity at which retail rates remain unchanged													14.50%
Maximum increase in rate RSE													5.00%
Approximate Annual Reduction in CNP rate due to the expiration of the PPA						5,000,000
Under recovered certified PPA balance													9,000,000																																																																										7,000,000					2,000,000
Unrecovered Retail Revenue Requirement For Environmental Compliance													1,000,000
Under recovered environmental clause													21,000,000
Approved And Certified Energy From Wind-Powered Generating Facilities																200
Energy From Wind-Powered Generatiing Facilities																400
Period Which Deferred Regulatory Asset Account, Amortized													3 years
Period Which Afforded Regulatory Asset Treatment													5 years
Compliance-related Operation Maintenance Expenditures													43,000,000
Incremental Increase In Pension Cost													17,000,000
Approved billing rate under rate ECR up to (cents per KWH)													0.05910
Future stated rates under rate Ecr factor in terms of per units													0.02681
Under recovered fuel cost										31,000,000			4,000,000	31,000,000
Annual Rate Change Limit Under Performance Evaluation Plan, Percent																																										1.99%					1.893%							1.936%
Annual Rate Change Under Performance Evaluation Plan, Amount																																										15,800,000					17,400,000							16,100,000
Maximum Period for recovery deferred storm-related operations and maintenance costs and any future reserve deficit													24 months
Old Natural Disaster Reserve Authorized Limit													75,000,000
Deferral of maintenance costs																																																																																																						38,000,000
Operating lease, initial term																																						10 years			10 years																																10 years
Estimated remaining useful life of plant																																																																									P30Y
Maximum total rate NDR charge per month, non-residential customer account													10
Maximum total rate NDR charge per month, residential customer account													5
Estimated cost associated with repairing damage facility to operation and maintenance expenses												42,000,000
Estimated cost associated with repairing damage facility to capital expenditure												161,000,000
Accumulated NDR reserve reflected as other regulatory liabilities, deferred													103,000,000	110,000,000
Number of units for which outage operations and maintenance expenses accrued													2
Period over which deferred costs are being amortized to nuclear operations and maintenance expenses													18 months
Nuclear outage operations and maintenance expenses decreased														50,000,000
Nuclear outage expense									31,000,000		38,000,000		31,000,000	38,000,000
Number of units for which actual nuclear outage expenses deferred to regulatory asset account													1
Maximum projected retail ROE allowed to earn																								10.25%	10.25%
Amortization of regulatory liability (up to one third) if Georgia Power does not file for retail base rate increase																								216,000,000	108,000,000
Maximum retail ROE allowed to earn																								10.15%	9.75%
Amount of regulatory liability amortized																								174,000,000	41,000,000
Number of Intervenors																								8
Expected remaining regulatory liability to be amortized in next two years																						92,000,000
Amortization Period of Other Cost of Removal Obligations																						3 years		3 years
Increase in traditional base tariff rates																		347,000,000
Estimated increase in DSM tariffs																		31,000,000
Estimated increase in ECCR tariff																		168,000,000
Increase in Municipal Franchise Fee tariff rates																		16,000,000
Base Revenue under Alternate Base Plan																		562,000,000
Estimated increase in tariff two in 2012																															17,000,000
Increased traditional base tariffs to recover revenue in year one																														122,000,000
Increased traditional base tariffs to recover revenue in year two																																																																																																					58,000,000
Estimated increase in tariff two in 2013																												14,000,000
Set percentage of ROE under ARP																						11.15%
Retail ROE, Minimum																						10.25%
Retail ROE, Maximum																						12.25%
Portion of actual earnings above approved ROE band refunded to customers																						66.66667%
Portion of actual earnings above approved ROE band retained by Georgia Power																						33.33333%
Refunds related to earnings																						0
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
Additional Capacity of Units Included In Application Request By Subsidiaries For Future Period Requests																						50													80
Capacity Of Units Included In Request by Subsidiaries For Decertification Of Units																			243			2,093																																																		28				1,016	579	122	316	32
Extension Period For Mercury And Air Toxics Standards																						1 year
Other Utility Plant, Net	263,000,000	55,000,000																				263,000,000	55,000,000
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress																																	13,000,000	65,000,000																																	69,774,000
Jointly Owned Utility Plant, Ownership Construction Work In Progress Amortization Period																																	3 years
Certain wholesale capacity scheduled to return to retail service in future period																						495
Increase in total annual billing based on fuel cost recovery rate approved by Georgia Power																						122,000,000							567,000,000			43,000,000
Adjustment to fuel cost recovery rate if under recovered fuel balance exceeds budget																						215,000,000
Adjustment To FuelCost Recovery Rate If Under Recovered Fuel Balance Exceeds Budget Thereafter																						200,000,000
Required Period For Options And Hedges																						24 months
Under recovered fuel balance																						230,000,000
Additional Solar Capacity																						210
Additional Solar Capacity Period																						3 years
Number of Plants For Decertification																						16
Recovery of project financing cost as per Legislation																						2,300,000,000	1,700,000,000
Reduction in projected in-service cost due to recovered cost																						4,400,000,000
Increase In NCCR Tariff Year One																						223,000,000
Increase In NCCR Tariff Year Two																						35,000,000
Increase In NCCR Tariff Year Three																						50,000,000
Total certified cost																						6,400,000,000
Amortization to earnings of financing costs capitalized over the five year period																						91,000,000
Amortization period for financing costs collected																						5 years
Costs included in CWIP																						55,000,000																2,470,000,000
Electric generating capacity in Mega Watts under consortium agreement																										1,100
Percentage of proportionate share owed in Consortium Agreement																						45.70%
Estimated Adjustment to Contract Price Related to Issues that May Impact Project Budget and Schedule																						425,000,000
Regulatory liability for state income tax credits amortization period	21 months																					21 months
Retail Rate of Return on Common Equity																																																																					9.25%		11.25%
Average Retail Rate of Return on Common Equity																																																																10.25%
Increase in Retail Rates and Charges in Next Fiscal Year																																																																4,000,000
Interim Retail Rate Increase																																																																		38,500,000
Increase in Retail Rates and Charges																																																																	64,000,000
Retail Rate Increase (Decrease)																																																													0.019		0.027
Units Using By Residential Customer																																																													1,000	1,000	1,000
Projected fuel cost over or under recovery threshold, as a percentage of projected fuel revenue																																																																10.00%				10.00%
Percentage of Decrease in Fuel Rates																																																														7.80%
Decrease in Annual Billings for Fuel Costs																																																														58,800,000
Over recovered fuel balance																																																				3,700,000																																						17,100,000	9,900,000
Period Adjustment For SRR Rate Level																																						3 years
Purchased Power Over (Under) Recovered Balance Percentage																																																																10.00%
PurchasedPowerOverUnderRecoveredBalance																																																																																											8,000,000		800,000
Under Recovered Environmental Cost																																																																																													1,900,000
Over Recovered Environmental Cost																																																																																											10,000,000
Percent ownership													14.00%																																												50.00%							50.00%			50.00%
Estimated cost of project																																																							660,000,000									660,000,000
Period of Establishment of Conservation Goals, in Years																																																																5 years
Period Numeric Conservation Goals Cover, in Years																																																																10 years
Under Recovered Energy Conservation Costs																																																																																													800,000
Over Recovered Energy Conservation Costs																																																																																											3,100,000
Proposed property damage reserve																																													3,800,000								3,600,000
Proposed change in annual revenue, percent																																												0.30%
Percentage of Decrease in Annual Revenue After Revised Notice																																												0.16%
Estimated cost of project, proportionate share																																																							330,000,000
Project expenditures, cumulative																																						146,600,000
Project expenditures, cumulative, proportionate share																																						73,300,000
Revenue request to recover financing costs for stipulated rate increase																																											55,300,000															55,300,000		58,600,000
Recovered and amortization periods as approved by appropriate state PSC																																																																						14 years
Change in annual revenue, percent																																																																																														(4.70%)	3.30%		5.50%
Over recovered fuel cost																																														42,400,000																																																56,600,000	14,300,000	19,000,000	2,200,000	2,100,000
Amount of Over Recovered Emissions Allowance Cost																																																																																															1,700,000	400,000
New Request Of Settlement Agreement																																						30 days
Settlement Agreement To Increase Rates																																						172,000,000																					172,000,000
Number Of Days For PSC Decision																																						50 days
Collaboration Period To File Settlement Agreement																																						3 months
Beginning Period Of Operation Of Plant																																						7 years
Period Of Time For Decision On Rate Recovery Plan Within Filing																																						4 months
Integrated Coal Gasification Combined Cycle [Abstract]
Plant capacity under coal gasification combined cycle technology in Mega Watts																																					582
Estimated cost																																																																										2,400,000,000
Prudence Review Of Plant Cost Within Settlement Agreement																																						6 months
Period Rate Plan For Cost Accrued Through Additional Prudence Review																																						7 years
Recovery Of Annual Revenue Requirement																																																																										150,000,000
Costs associated with CCP12 grant funds																																						245,300,000
Maximum cap construction cost																																						2,880,000,000
Percentage of financing costs of construction work in progress																																						100.00%
Portion of deferred construction cost under review																																						46,000,000
Estimated capital cost of mine																																						245,000,000
Cost Incurred for Use of Mine																																						163,300,000
Term of management fee contract																																						40 years																																					40 years
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																																						361,600,000
Tax credits not available for use until future period																																						170,900,000
Carry Forward For Unused Tax Credits																																						20 years
Additional Bonus Depreciation For Property Acquired Future Periods																																						50.00%
Purchase of interest in plant																																						17.50%																		17.50%
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																																						78,400,000											132,000,000
Maximum Period to Refund Deposit upon Termination of Asset Purchase Agreement																																						60 days
Cost incurred by Mississippi Power associated with plant including regulatory filing costs																																						2,510,000,000
Costs included in CWIP																						55,000,000																2,470,000,000
Cost deferred in other regulatory assets																																						34,900,000
Other deferred charges and assets																																						3,800,000
Previously expensed																																						1,000,000
Deferred Construction Cost Under Review																																						51,000,000
PSC Approved Annual Property Damage Reserve Accrual																																						3,200,000																										3,500,000
Loss Contingency, Estimate of Possible Loss																																																																																																			10,500,000
Storm Reserve Balance																																						58,800,000
Reduced Percentage Interest Transferred under Asset Purchase Agreement																																						15.00%
Deposit Received																																						$ 150,000,000