Financing - Short-term Borrowings (Details) (USD $)																		12 Months Ended
	Dec. 31, 2011	Dec. 31, 2012 Other Energy Service Contracts [Member]	Dec. 31, 2011 Other Energy Service Contracts [Member]	Dec. 31, 2012 Commercial paper [Member]	Dec. 31, 2011 Commercial paper [Member]	Dec. 31, 2011 Short-term bank debt [Member]	Dec. 31, 2012 Gulf Power [Member] Other Energy Service Contracts [Member]	Dec. 31, 2011 Gulf Power [Member] Other Energy Service Contracts [Member]	Dec. 31, 2012 Gulf Power [Member] Commercial paper [Member]	Dec. 31, 2011 Gulf Power [Member] Commercial paper [Member]	Dec. 31, 2012 Southern Power [Member]	Sep. 30, 2012 Southern Power [Member]	Jun. 30, 2012 Southern Power [Member]	Dec. 31, 2012 Southern Power [Member] Commercial paper [Member]	Dec. 31, 2011 Southern Power [Member] Commercial paper [Member]	Dec. 31, 2012 Mississippi Power [Member]	Oct. 20, 2011 Mississippi Power [Member]	Dec. 31, 2012 Alabama Power [Member]	Dec. 31, 2012 Georgia Power [Member]	Dec. 31, 2011 Georgia Power [Member]	Dec. 31, 2011 Georgia Power [Member] Commercial paper [Member]	Dec. 31, 2011 Georgia Power [Member] Short-term bank debt [Member]
Short-term Debt [Line Items]
Notes Payable, Related Parties		$ 5,000,000	$ 6,000,000				$ 3,200,000	$ 3,600,000
Taxable Revenue Bonds																51,500,000
Debt Instrument, Face Amount											500,000	900,000	4,100,000				270,000,000		2,300,000,000
Short-term borrowings
Short-term Debt at the End of the Period, Amount Outstanding	854,000,000			820,000,000	654,000,000	200,000,000			124,000,000	111,000,000				71,000,000	180,000,000					513,000,000	313,000,000	200,000,000
Short-term Debt at the End of the Period, Weighted Average Interest Rate	0.50%			0.30%	0.30%	1.20%			0.30%	0.20%				0.50%	0.50%					0.50%	0.20%	1.20%
Short-term Debt During the Period, Maximum Amount Outstanding																		$ 45,000,000