Income Taxes - Current and Deferred Income Tax Provisions (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Federal -
Current	$ 177,000	$ 57,000	$ 42,000
Deferred	1,011,000	1,035,000	898,000
Total federal taxes	1,188,000	1,092,000	940,000
State -
Current	61,000	8,000	(54,000)
Deferred	85,000	119,000	140,000
Total state taxes	146,000	127,000	86,000
Income taxes	1,334,000	1,219,000	1,026,000
Southern Power [Member]
Federal -
Current	(133,100)	61,600	4,300
Deferred	210,400	12,400	46,500
Total federal taxes	77,300	74,000	50,800
State -
Current	(3,000)	9,800	6,500
Deferred	18,300	(7,900)	18,100
Total state taxes	15,300	1,900	24,600
Income taxes	92,621	75,857	75,356
Mississippi Power [Member]
Federal -
Current	1,212	(27,099)	5,399
Deferred	42,929	65,206	35,367
Total federal taxes	44,141	38,107	40,766
State -
Current	1,656	(2,473)	3,319
Deferred	4,594	6,559	2,190
Total state taxes	6,250	4,086	5,509
Income taxes	50,391	42,193	46,275
Gulf Power [Member]
Federal -
Current	(92,610)	(1,548)	(14,115)
Deferred	161,096	56,087	77,452
Total federal taxes	68,486	54,539	63,337
State -
Current	(2,484)	(412)	2,948
Deferred	13,209	7,141	5,229
Total state taxes	10,725	6,729	8,177
Income taxes	79,211	61,268	71,514
Alabama Power [Member]
Federal -
Current	262,000	20,000	52,000
Deferred	137,000	377,000	333,000
Total federal taxes	399,000	397,000	385,000
State -
Current	51,000	(1,000)	1,000
Deferred	27,000	82,000	77,000
Total state taxes	78,000	81,000	78,000
Income taxes	477,000	478,000	463,000
Georgia Power [Member]
Federal -
Current	273,000	106,000	147,000
Deferred	370,000	479,000	312,000
Total federal taxes	643,000	585,000	459,000
State -
Current	38,000	19,000	(36,000)
Deferred	7,000	21,000	30,000
Total state taxes	45,000	40,000	(6,000)
Income taxes	$ 688,000	$ 625,000	$ 453,000