Financing - Textual (Details) (USD $)	12 Months Ended					12 Months Ended			1 Months Ended	3 Months Ended		12 Months Ended										12 Months Ended						12 Months Ended								0 Months Ended		1 Months Ended				12 Months Ended							1 Months Ended		1 Months Ended		1 Months Ended		3 Months Ended		12 Months Ended		12 Months Ended													12 Months Ended		1 Months Ended		0 Months Ended	1 Months Ended	12 Months Ended
	Dec. 31, 2012 Employee	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Trust Preferred Securities Subject to Mandatory Redemption [Member]	Dec. 31, 2011 Trust Preferred Securities Subject to Mandatory Redemption [Member]	Dec. 31, 2012 Georgia Power [Member]	Dec. 31, 2011 Georgia Power [Member]	Dec. 31, 2010 Georgia Power [Member]	May 31, 2012 Georgia Power [Member] Repayment of Debt [Member]	Mar. 31, 2012 Georgia Power [Member] Repayment of Debt [Member]	Dec. 31, 2012 Southern Power and Traditional Operating Companies [Member] Senior Notes [Member]	Dec. 31, 2012 Gulf Power [Member] Employee		Dec. 31, 2011 Gulf Power [Member]	Dec. 31, 2010 Gulf Power [Member]	Nov. 30, 2012 Gulf Power [Member]	May 31, 2012 Gulf Power [Member] Series Two Thousand Twelve A Three Point One Percent Due May Fifteenth Two Thousand Twenty Two [Member]	May 31, 2012 Gulf Power [Member] Series F Five Point Six Percent Due April One Two Thousand Thirty Three [Member]	May 31, 2012 Gulf Power [Member] Series H Five Point Two Five Percent Due July Fifteenth Two Thousand Thirty Three [Member]	Dec. 31, 2012 Southern Company [Member]	Dec. 31, 2011 Southern Company [Member]	Dec. 31, 2012 Alabama Power [Member] Employee	Dec. 31, 2011 Alabama Power [Member]	Dec. 31, 2010 Alabama Power [Member]	Dec. 31, 2012 Alabama Power [Member] Trust Preferred Securities Subject to Mandatory Redemption [Member]	Dec. 31, 2011 Alabama Power [Member] Trust Preferred Securities Subject to Mandatory Redemption [Member]	Dec. 31, 2012 Alabama Power [Member] Senior Notes And Pollution Control Bond [Member]	Dec. 31, 2012 Alabama Power [Member] Solid Waste Disposal Revenue Bond Series 2008 [Member]	Dec. 31, 2012 Southern Power [Member]	Dec. 31, 2011 Southern Power [Member]	Dec. 31, 2010 Southern Power [Member]	Sep. 30, 2012 Southern Power [Member]	Jun. 30, 2012 Southern Power [Member]	Nov. 17, 2011 Southern Power [Member] Series 2011A 5.15% Senior Notes due September 15, 2041 [Member]	Sep. 22, 2011 Southern Power [Member] Series 2011A 5.15% Senior Notes due September 15, 2041 [Member]	Dec. 19, 2011 Southern Power [Member] Series B 6.25% Senior Notes due July 15, 2012 [Member]	Oct. 20, 2011 Mississippi Power [Member]	Nov. 30, 2012 Mississippi Power [Member]	Sep. 30, 2012 Mississippi Power [Member]	Mar. 31, 2012 Mississippi Power [Member]	Oct. 31, 2011 Mississippi Power [Member]	Dec. 31, 2012 Mississippi Power [Member]		Dec. 31, 2011 Mississippi Power [Member]	Dec. 31, 2010 Mississippi Power [Member]	Mar. 06, 2012 Mississippi Power [Member]	Oct. 20, 2011 Mississippi Power [Member] Plant Daniel Units 3 and 4 [Member]	Oct. 31, 2011 Mississippi Power [Member] Revenue Bonds [Member]	Mar. 31, 2012 Mississippi Power [Member] Series 2012A 4.25% Senior Notes Due March 15, 2042 [Member]	Aug. 31, 2012 Mississippi Power [Member] Series 2012A 4.25% Senior Notes Due March 15, 2042 [Member]	Mar. 31, 2012 Mississippi Power [Member] Series 2011A Senior Notes Due October 15, 2016 [Member]	Oct. 31, 2011 Mississippi Power [Member] Series 2011A Senior Notes Due October 15, 2016 [Member]	May 31, 2012 Mississippi Power [Member] Series E 5-5/8% Senior Notes Due May May 1, 2033 [Member]	Sep. 30, 2012 Mississippi Power [Member] Repayment of Debt [Member]	Mar. 31, 2012 Mississippi Power [Member] Repayment of Debt [Member]	Dec. 31, 2012 Alabama Power and Gulf Power [Member] Secured Debt [Member]	Dec. 31, 2012 Traditional Operating Companies [Member]	Dec. 31, 2011 Traditional Operating Companies [Member]	Dec. 31, 2012 Traditional Operating Companies [Member] Repayment of Debt [Member]	Dec. 31, 2012 Minimum [Member] Gulf Power [Member]	Dec. 31, 2012 Maximum [Member] Gulf Power [Member]	Dec. 31, 2012 Repayment of Debt [Member] Subsequent Event [Member] Alabama Power [Member]	Aug. 31, 2012 Revenue Bonds [Member] Mississippi Power [Member] Mississippi Business Finance Corporation Taxable Revenue Bonds, Series 2012B [Member]	Aug. 31, 2012 Revenue Bonds [Member] Mississippi Power [Member] Mississippi Business Finance Corporation Taxable Revenue Bonds, Series 2012C [Member]	Dec. 31, 2012 Revenue Bonds [Member] Mississippi Power [Member] Mississippi Business Finance Corporation Taxable Revenue Bonds, Series Two Thousand Twelve A [Member]	Aug. 31, 2012 Revenue Bonds [Member] Mississippi Power [Member] Mississippi Business Finance Corporation Taxable Revenue Bonds, Series Two Thousand Twelve A [Member]	Dec. 31, 2012 Unsecured Debt [Member] Alabama Power [Member]	Dec. 31, 2011 Unsecured Debt [Member] Alabama Power [Member]	Dec. 31, 2012 Secured Debt [Member] Georgia Power [Member]	Dec. 31, 2011 Secured Debt [Member] Georgia Power [Member]	Dec. 31, 2012 Secured Debt [Member] Alabama Power [Member]	Dec. 31, 2012 Loans Payable [Member] Gulf Power [Member]	Dec. 31, 2012 Plant Daniel [Member] Gulf Power [Member]	Oct. 31, 2011 Plant Daniel Units Three and Four [Member] Mississippi Power [Member]	Oct. 20, 2011 Plant Daniel Units Three and Four [Member] Mississippi Power [Member]	Jan. 20, 2012 Southern Company [Member] Common Stock [Member] Gulf Power [Member]	Feb. 28, 2013 Southern Company [Member] Common Stock [Member] Gulf Power [Member]	Dec. 31, 2012 Performance Shares [Member] Alabama Power [Member]	Dec. 31, 2012 Performance Shares [Member] Mississippi Power [Member]	Dec. 31, 2012 Bank Loan Obligations [Member] Georgia Power [Member]	Dec. 31, 2012 Senior Notes [Member] Georgia Power [Member]
Debt Instrument [Line Items]
Number of Employees Participating in Stock Option Plan	6,026					1,402						218										1,057
Minimum Percentage of Transfer Performance Shares to Common Stock Based on Actual Shareholder Return	0.00%					0.00%						0.00%																																																																		0.00%	0.00%
Maximum Percentage of Transfer Performance Shares to Common Stock Based on Actual Shareholder Return	200.00%					200.00%						200.00%																																																																		200.00%	200.00%
Financing (Textual) [Abstract]
Proceeds from issuance of junior subordinated notes	$ 206,000,000	$ 206,000,000																				$ 206,000,000	$ 206,000,000
Preferred securities, outstanding				200,000,000	200,000,000																				200,000,000	200,000,000
Senior notes, current	2,085,000,000	1,200,000,000				1,675,000,000	200,000,000															250,000,000	500,000,000																			50,000,000		0
Long term debt maturities in 2013	2,340,000,000					1,700,000,000						60,000,000																														276,500,000
Long term debt maturities in 2014	448,000,000					5,000,000						75,000,000																														300,000,000
Long term debt maturities in 2015	2,440,000,000					1,100,000,000																																				0
Long term debt maturities in 2016	1,370,000,000					260,000,000						110,000,000																														0
Long term debt maturities in 2017	1,140,000,000					456,000,000						85,000,000																														35,000,000
Bank Short Term Loan Agreement Principal Amount									200,000,000	250,000,000																																												40,000,000	75,000,000				565,000,000
Long-term debt maturities, 2013	1,436,000,000	1,436,000,000				1,025,000,000	1,025,000,000					60,000,000		60,000,000								250,000,000	250,000,000				250,000,000															50,000,000		50,000,000
Long-term Debt, Maturities, Repayments of Principal in Year Two	434,000,000	437,000,000										75,000,000		75,000,000								0
Long-term debt maturities, 2014	2,375,000,000	1,175,000,000				1,050,000,000	250,000,000															400,000,000	0				454,000,000
Long-term debt maturities, 2016	1,360,000,000	1,210,000,000				250,000,000	250,000,000					110,000,000		110,000,000								200,000,000	200,000,000				200,000,000															300,000,000		150,000,000
Long-term debt maturities, 2016	1,095,000,000	1,095,000,000				450,000,000	450,000,000					85,000,000		85,000,000								525,000,000	525,000,000				561,000,000															35,000,000		35,000,000
Repayments of bank debt																																							40,000,000	75,000,000		75,000,000
Bank Loans							450,000,000					30,000,000																														175,000,000		240,000,000
Bank loans, period of extension																																						366 days				366 days
Description of variable rate basis	one-month					one-month																																		one-month		one-month LIBOR
First Advance On Bank Loan																																										50,000,000
Second Advance On Bank Loan																																										50,000,000
Bank loans outstanding							450,000,000																																			175,000,000		240,000,000
Aggregate Principal Amount of Floating Rate Bank Loan									200,000,000	250,000,000																												100,000,000
Debt Instrument, Face Amount						2,300,000,000					4,000,000,000						100,000,000	61,000,000	30,000,000										500,000			900,000	4,100,000	575,000,000			270,000,000												250,000,000	450,000,000	300,000,000	150,000,000												21,250,000	8,970,000		1,000,000,000
Unsecured Debt																																																																																250,000,000	850,000,000
Redemption Amount of Principal Notes																																																																			450,000,000
Fixed stated interest rate of debt obligation						7.90%	7.40%										3.10%	5.60%	5.25%																5.15%	6.25%	7.13%					9.967%						7.13%	4.25%		2.35%		5.625%																						7.13%
Prepayment of debt																													2,500,000																												2,800,000,000					500,000,000
Debt Instrument, Additional Face Amount																																																		200,000,000	150,000,000
Ratio of indebtedness to capitalization, debt covenant, required	65.00%					65.00%						65.00%										65.00%							65.00%													65.00%
Senior Notes outstanding	17,400,000,000	15,900,000,000				7,900,000,000	6,400,000,000					945,000,000		936,400,000						1,300,000,000	1,800,000,000								1,300,000,000	1,300,000,000												1,100,000,000		630,000,000																							4,800,000,000	4,800,000,000
Secured Debt												41,000,000
Long-term Debt																																																																					50,000,000	55,000,000	153,000,000
Repayments of Pollution Control Bond						284,000,000	339,000,000	516,000,000				13,000,000		0	0							1,000,000	4,000,000	0				700,000
Pollution control revenue bonds, outstanding						1,800,000,000	1,800,000,000					309,000,000		309,000,000		13,000,000						1,200,000,000																				82,700,000		82,700,000												194,000,000	3,400,000,000	3,400,000,000													153,000,000		41,000,000
Aggregate Pollution Control Revenue Bond						284,000,000
Redemption Amount of Principal						284,000,000
Revenue bond obligations face value																																									270,000,000																																	270,000,000
Other revenue bond obligation																																										50,000,000		50,000,000
Taxable Revenue Bonds																																										51,500,000
Deposit Received																																										150,000,000
Purchased price of plant																																					85,000,000										85,000,000																												84,800,000
Amount of Principal obligation assumed under Lease																																					270,000,000
Revenue Bond Obligations Fair Value																																					346,000,000
Commitment fee percentage (less than 1/4 of 1%)	0.00%					0.25%						0.25%										0.25%							0.25%													0.25%
Unused credit with banks	5,173,000,000					1,740,000,000						275,000,000								1,000,000,000		1,308,000,000							500,000,000													300,000,000
Remarketed pollution control bonds																						207,000,000
Amount of Variable Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support	1,800,000,000					865,000,000																793,000,000																				40,100,000
Short-term debt outstanding, regulatory approved maximum																						2,300,000,000
Capitalized lease obligations	80,000,000	93,000,000				50,000,000	55,000,000																																			0		633,000
Redeemable preferred stock, redemption period																																																												5 years	10 years
Redemption price of redeemable preferred stock, as a percent of liquidation amount						100.00%						100.00%																														100.00%
Stock Issued During Period, Shares, New Issues																																																																												400,000	400,000
Stock Issued During Period, Value, New Issues	397,000,000	725,000,000	772,000,000									40,000,000		50,000,000	50,000,000																																																													40,000,000	40,000,000
Term of bank loan																																																																								1 year
Debt Instrument, Term Year Two																																																																								2 years
Line of Credit Facility, Current Borrowing Capacity												275,000,000																	500,000,000
Line of Credit Facility, Maximum Borrowing Capacity	5,183,000,000					1,750,000,000						275,000,000	[1]							1,000,000,000		1,308,000,000							500,000,000													300,000,000	[1]
Line of Credit Facility, Amount Available to Support Variable Rate Pollution Control Revenue Bonds												69,000,000
Line of Credit Facility, Amount Available for Commercial Paper Program and General Corporate Purposes												206,000,000
Short-term borrowings related to other energy service contracts						2,000,000
Interest Rate Hedge Settlement																																								300,000,000									250,000,000		50,000,000
Gain (loss) on settlement of interest rate swaps	(19,000,000)	(28,000,000)	(1,000,000)																										(200,000)	100,000	1,500,000											16,000,000							(13,300,000)		(2,700,000)
Gain (loss) on settlement of interest rate swaps, period of amortization to earnings																																																	10 years		10 years
Repayments of senior debt						850,000,000	427,000,000	1,112,000,000				91,363,000		608,000	215,515,000							950,000,000	750,000,000	250,000,000					0	575,000,000	0					575,000,000						90,000,000		0	0								90,000,000
Significant Acquisitions and Disposals, Acquisition Costs, Assumption of Debt, at Fair Value																																																																											346,051,000
Fair value adjustment at date of purchase																																																																											76,051,000
Debt Instrument, Face Amount, Authorized to Issue																																																															21,250,000	21,250,000		42,500,000
Deposit Liability, Current																																														$ 150,000,000
Maximum Period of Discretion																																										15 days
Maximum Period to Refund Deposit upon Termination of Asset Purchase Agreement																																										60 days
Maximum Period to Refund Deposit, Upon Notification, Due to Not Meeting Minimum Credit Rating																																										15 days
Projected cash flows from fixed price PPAs, as a percentage of total projected cash flows for the next 12 months																													80.00%
Ratio of indebtedness to capitalization, actual, end of period																													60.00%

[1] No credit arrangements expire after 2014.