Summary of Significant Accounting Policies - Property, Plant, and Equipment (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 Alabama Power [Member]	Dec. 31, 2012 Alabama Power [Member]	Dec. 31, 2013 Georgia Power [Member]	Dec. 31, 2012 Georgia Power [Member]	Dec. 31, 2013 Gulf Power [Member]	Dec. 31, 2012 Gulf Power [Member]	Dec. 31, 2013 Mississippi Power [Member]	Dec. 31, 2012 Mississippi Power [Member]	Oct. 20, 2011 Plant Daniel Units 3 and 4 [Member] Mississippi Power [Member]
Public Utilities, Property, Plant and Equipment, Plant in Service [Abstract]
Generation	$ 35,360,000,000	$ 33,444,000,000	$ 11,314,000,000	$ 11,110,000,000	$ 14,872,000,000	$ 14,567,000,000	$ 2,607,166,000	$ 2,598,773,000	$ 1,475,264,000	$ 1,363,269,000
Transmission	9,289,000,000	8,747,000,000	3,287,000,000	3,137,000,000	4,859,000,000	4,581,000,000	473,378,000	429,341,000	633,903,000	563,037,000
Distribution	16,499,000,000	15,958,000,000	5,934,000,000	5,714,000,000	8,620,000,000	8,373,000,000	1,117,024,000	1,069,065,000	828,470,000	802,718,000
General	3,958,000,000	4,208,000,000	1,545,000,000	1,434,000,000	1,753,000,000	1,695,000,000	164,065,000	161,379,000	439,721,000	225,723,000
Plant acquisition adjustment	123,000,000	124,000,000	12,000,000	12,000,000	28,000,000	28,000,000	2,031,000	2,286,000	81,412,000	81,412,000	81,400,000
Utility plant in service	65,229,000,000	62,481,000,000
Information technology equipment and software	242,000,000	230,000,000
Communications equipment	437,000,000	430,000,000
Other	113,000,000	110,000,000
Other plant in service	792,000,000	770,000,000
Total plant in service	$ 66,021,000,000	$ 63,251,000,000	$ 22,092,000,000	$ 21,407,000,000	$ 30,132,000,000	$ 29,244,000,000	$ 4,363,664,000	$ 4,260,844,000	$ 3,458,770,000	$ 3,036,159,000