Income Taxes - Changes in Unrecognized Tax Benefits (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Changes in unrecognized tax benefits [Roll Forward]
Unrecognized tax benefits at beginning of year	$ 70,000,000	$ 120,000,000	$ 296,000,000
Tax positions from current periods	3,000,000	13,000,000	46,000,000
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	0	7,000,000	1,000,000
Tax positions decrease from prior periods	(66,000,000)	(56,000,000)	(111,000,000)
Reductions due to settlements	0	(10,000,000)	(112,000,000)
Reductions due to expired statute of limitations	0	(4,000,000)	0
Unrecognized tax benefits at end of year	7,000,000	70,000,000	120,000,000
Southern Power [Member]
Changes in unrecognized tax benefits [Roll Forward]
Unrecognized tax benefits at beginning of year	2,900,000	2,600,000	2,300,000
Tax positions from current periods	1,600,000	700,000	400,000
Tax positions decrease from prior periods	(3,000,000)	(200,000)	(100,000)
Reductions due to settlements	0	(200,000)	0
Unrecognized tax benefits at end of year	1,500,000	2,900,000	2,600,000
Gulf Power [Member]
Changes in unrecognized tax benefits [Roll Forward]
Unrecognized tax benefits at beginning of year	5,007,000	2,892,000	3,870,000
Tax positions from current periods	45,000	2,630,000	540,000
Tax positions decrease from prior periods	(5,007,000)	515,000	(1,518,000)
Reductions due to settlements	0	(1,030,000)	0
Unrecognized tax benefits at end of year	45,000	5,007,000	2,892,000
Mississippi Power [Member]
Changes in unrecognized tax benefits [Roll Forward]
Unrecognized tax benefits at beginning of year	5,755,000	4,964,000	4,288,000
Tax positions from current periods	226,000	1,186,000	1,486,000
Tax positions decrease from prior periods	(2,141,000)	(26,000)	(810,000)
Reductions due to settlements	0	(369,000)	0
Unrecognized tax benefits at end of year	3,840,000	5,755,000	4,964,000
Alabama Power [Member]
Changes in unrecognized tax benefits [Roll Forward]
Unrecognized tax benefits at beginning of year	31,000,000	32,000,000	43,000,000
Tax positions from current periods	0	5,000,000	6,000,000
Tax positions decrease from prior periods	(31,000,000)	(4,000,000)	(17,000,000)
Reductions due to settlements	0	(2,000,000)	0
Unrecognized tax benefits at end of year	0	31,000,000	32,000,000
Georgia Power [Member]
Changes in unrecognized tax benefits [Roll Forward]
Unrecognized tax benefits at beginning of year	23,000,000	47,000,000	237,000,000
Tax positions from current periods	0	3,000,000	9,000,000
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	0	3,000,000	0
Tax positions decrease from prior periods	(23,000,000)	(19,000,000)	(87,000,000)
Reductions due to settlements	0	(8,000,000)	(112,000,000)
Reductions due to expired statute of limitations	0	(3,000,000)	0
Unrecognized tax benefits at end of year	$ 0	$ 23,000,000	$ 47,000,000