Income Taxes - Deferred Tax Assets and Liabilities (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Deferred tax liabilities -
Total - deferred tax liabilities	$ 13,619,000,000	$ 12,127,000,000
Deferred tax assets -
Total - deferred tax assets	3,932,000,000	3,473,000,000
Total deferred tax liabilities, net	9,687,000,000	8,654,000,000
Portion included in current assets/(liabilities), net	237,000,000	125,000,000
Deferred state tax assets	68,000,000	86,000,000
Valuation allowance	54,000,000	56,000,000
Accumulated deferred income taxes	9,938,000,000	8,809,000,000
Asset retirement obligations-asset [Member]
Deferred tax assets -
Total - deferred tax assets	720,000,000	546,000,000
Unbilled revenues [Member]
Deferred tax assets -
Total - deferred tax assets	101,000,000	110,000,000
Accelerated depreciation [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	9,022,000,000	7,882,000,000
Other property basis differences [Member]
Deferred tax assets -
Total - deferred tax assets	134,000,000	134,000,000
Deferred costs [Member]
Deferred tax assets -
Total - deferred tax assets	39,000,000	55,000,000
Property basis differences [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	1,254,000,000	1,256,000,000
Leveraged lease basis differences [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	278,000,000	277,000,000
Employee benefit obligations [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	536,000,000	499,000,000
Deferred tax assets -
Total - deferred tax assets	1,678,000,000	1,594,000,000
Under recovered fuel clause [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	16,000,000	82,000,000
Premium on reacquired debt [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	84,000,000	111,000,000
Regulatory assets associated with employee benefit obligations [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	988,000,000	1,198,000,000
Regulatory assets associated with asset retirement obligations [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	1,108,000,000	546,000,000
Other deferred tax liabilities [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	333,000,000	276,000,000
Federal effect of state deferred taxes [Member]
Deferred tax assets -
Total - deferred tax assets	394,000,000	393,000,000
Over recovered fuel clause [Member]
Deferred tax assets -
Total - deferred tax assets	135,000,000	33,000,000
Cost of removal [Member]
Deferred tax assets -
Total - deferred tax assets	29,000,000	40,000,000
Tax credit carryforward [Member]
Deferred tax assets -
Total - deferred tax assets	256,000,000	129,000,000
Other Comprehensive Income Losses [Member]
Deferred tax assets -
Total - deferred tax assets	84,000,000	81,000,000
Other deferred tax assets [Member]
Deferred tax assets -
Total - deferred tax assets	362,000,000	358,000,000
Southern Power [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	642,200,000	402,700,000
Deferred tax assets -
Total - deferred tax assets	91,700,000	84,800,000
Total deferred tax liabilities, net	550,500,000	317,900,000
Portion included in current assets/(liabilities), net	200,000	1,900,000
Accumulated deferred income taxes	550,685,000	319,790,000
Southern Power [Member] | Accelerated depreciation and other property basis differences [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	632,900,000	394,800,000
Southern Power [Member] | Other property basis differences [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	3,100,000	3,300,000
Deferred tax assets -
Total - deferred tax assets	3,900,000	4,900,000
Southern Power [Member] | Investment tax credit carryforward [Member]
Deferred tax assets -
Total - deferred tax assets	28,600,000	21,800,000
Southern Power [Member] | Other deferred tax liabilities [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	6,200,000	4,600,000
Southern Power [Member] | Federal effect of state deferred taxes [Member]
Deferred tax assets -
Total - deferred tax assets	25,200,000	18,600,000
Southern Power [Member] | Tax credit carryforward [Member]
Deferred tax assets -
Total - deferred tax assets	1,100,000	1,100,000
Southern Power [Member] | Unrealized Loss [Member]
Deferred tax assets -
Total - deferred tax assets	15,700,000	19,100,000
Southern Power [Member] | Levelized capacity revenues [Member]
Deferred tax assets -
Total - deferred tax assets	4,500,000	8,200,000
Southern Power [Member] | Other deferred tax assets [Member]
Deferred tax assets -
Total - deferred tax assets	12,700,000	11,100,000
Gulf Power [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	804,881,000	585,680,000
Deferred tax assets -
Total - deferred tax assets	157,901,000	131,299,000
Total deferred tax liabilities, net	646,980,000	454,381,000
Portion included in current assets/(liabilities), net	1,972,000	4,597,000
Accumulated deferred income taxes	648,952,000	458,978,000
Gulf Power [Member] | Accelerated depreciation [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	696,502,000	496,392,000
Gulf Power [Member] | Employee benefit obligations [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	28,579,000	25,268,000
Gulf Power [Member] | Regulatory assets associated with employee benefit obligations [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	57,279,000	44,871,000
Gulf Power [Member] | Regulatory assets associated with asset retirement obligations [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	6,502,000	4,345,000
Gulf Power [Member] | Other deferred tax liabilities [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	16,019,000	14,804,000
Gulf Power [Member] | Federal effect of state deferred taxes [Member]
Deferred tax assets -
Total - deferred tax assets	20,656,000	16,684,000
Gulf Power [Member] | Postretirement benefits [Member]
Deferred tax assets -
Total - deferred tax assets	17,905,000	16,769,000
Gulf Power [Member] | Over recovered fuel clause [Member]
Deferred tax assets -
Total - deferred tax assets	6,922,000	2,531,000
Gulf Power [Member] | Pension and other employee benefits [Member]
Deferred tax assets -
Total - deferred tax assets	61,939,000	49,116,000
Gulf Power [Member] | Property reserve [Member]
Deferred tax assets -
Total - deferred tax assets	13,773,000	13,159,000
Gulf Power [Member] | Tax credit carryforward [Member]
Deferred tax assets -
Total - deferred tax assets	938,000	7,151,000
Gulf Power [Member] | Other Comprehensive Income Losses [Member]
Deferred tax assets -
Total - deferred tax assets	993,000	1,353,000
Gulf Power [Member] | Asset retirement obligation [Member]
Deferred tax assets -
Total - deferred tax assets	6,502,000	4,345,000
Gulf Power [Member] | Other deferred tax assets [Member]
Deferred tax assets -
Total - deferred tax assets	28,273,000	20,191,000
Mississippi Power [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	658,814,000	533,306,000
Deferred tax assets -
Total - deferred tax assets	419,836,000	296,533,000
Total deferred tax liabilities, net	238,978,000	236,773,000
Portion included in current assets/(liabilities), net	35,815,000	33,624,000
Accumulated deferred income taxes	274,793,000	270,397,000
Mississippi Power [Member] | Accelerated depreciation [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	385,899,000	356,857,000
Mississippi Power [Member] | Other property basis differences [Member]
Deferred tax assets -
Total - deferred tax assets	980,000	2,918,000
Mississippi Power [Member] | Investment tax credit carryforward [Member]
Deferred tax assets -
Total - deferred tax assets	170,938,000	77,400,000
Mississippi Power [Member] | Unbilled revenues [Member]
Deferred tax assets -
Total - deferred tax assets	11,642,000	14,951,000
Mississippi Power [Member] | Property basis differences [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	72,451,000	48,268,000
Mississippi Power [Member] | Under recovered fuel clause [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	9,492,000	7,880,000
Mississippi Power [Member] | Regulatory assets associated with employee benefit obligations [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	68,717,000	52,410,000
Mississippi Power [Member] | Regulatory assets associated with asset retirement obligations [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	16,851,000	7,557,000
Mississippi Power [Member] | Regulatory assets associated with Kemper IGCC [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	10,492,000	4,618,000
Mississippi Power [Member] | Other deferred tax liabilities [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	33,886,000	23,802,000
Mississippi Power [Member] | Federal effect of state deferred taxes [Member]
Deferred tax assets -
Total - deferred tax assets	9,097,000	10,899,000
Mississippi Power [Member] | Over recovered fuel clause [Member]
Deferred tax assets -
Total - deferred tax assets	38,955,000	30,050,000
Mississippi Power [Member] | Premium on long-term debt [Member]
Deferred tax assets -
Total - deferred tax assets	26,778,000	29,820,000
Mississippi Power [Member] | Pension and other employee benefits [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	33,756,000	18,283,000
Deferred tax assets -
Total - deferred tax assets	87,416,000	70,255,000
Mississippi Power [Member] | Property insurance [Member]
Deferred tax assets -
Total - deferred tax assets	23,171,000	25,349,000
Mississippi Power [Member] | Long-term service agreement [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	0	5,231,000
Deferred tax assets -
Total - deferred tax assets	5,544,000	0
Mississippi Power [Member] | Rate Differential [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	27,270,000	8,400,000
Mississippi Power [Member] | Asset retirement obligation [Member]
Deferred tax assets -
Total - deferred tax assets	16,851,000	7,557,000
Mississippi Power [Member] | Interest rate hedges [Member]
Deferred tax assets -
Total - deferred tax assets	5,644,000	5,763,000
Mississippi Power [Member] | Other deferred tax assets [Member]
Deferred tax assets -
Total - deferred tax assets	22,820,000	21,571,000
Georgia Power [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	6,365,000,000	5,759,000,000
Deferred tax assets -
Total - deferred tax assets	1,656,000,000	1,402,000,000
Total deferred tax liabilities, net	4,709,000,000	4,357,000,000
Portion included in current assets/(liabilities), net	152,000,000	31,000,000
Accumulated deferred income taxes	4,861,000,000	4,388,000,000
Georgia Power [Member] | Accelerated depreciation [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	4,201,000,000	3,687,000,000
Georgia Power [Member] | Other property basis differences [Member]
Deferred tax assets -
Total - deferred tax assets	100,000,000	106,000,000
Georgia Power [Member] | Unbilled revenues [Member]
Deferred tax assets -
Total - deferred tax assets	39,000,000	45,000,000
Georgia Power [Member] | Deferred costs [Member]
Deferred tax assets -
Total - deferred tax assets	39,000,000	55,000,000
Georgia Power [Member] | Property basis differences [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	757,000,000	804,000,000
Georgia Power [Member] | Employee benefit obligations [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	255,000,000	257,000,000
Deferred tax assets -
Total - deferred tax assets	644,000,000	585,000,000
Georgia Power [Member] | Under recovered fuel clause [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	0	56,000,000
Georgia Power [Member] | Premium on reacquired debt [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	77,000,000	72,000,000
Georgia Power [Member] | Regulatory assets associated with employee benefit obligations [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	536,000,000	481,000,000
Georgia Power [Member] | Regulatory assets associated with asset retirement obligations [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	446,000,000	299,000,000
Deferred tax assets -
Total - deferred tax assets	446,000,000	299,000,000
Georgia Power [Member] | Other deferred tax liabilities [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	93,000,000	103,000,000
Georgia Power [Member] | Federal effect of state deferred taxes [Member]
Deferred tax assets -
Total - deferred tax assets	142,000,000	157,000,000
Georgia Power [Member] | Over recovered fuel clause [Member]
Deferred tax assets -
Total - deferred tax assets	89,000,000	0
Georgia Power [Member] | Cost of removal [Member]
Deferred tax assets -
Total - deferred tax assets	29,000,000	40,000,000
Georgia Power [Member] | Tax credit carryforward [Member]
Deferred tax assets -
Total - deferred tax assets	86,000,000	52,000,000
Georgia Power [Member] | Other deferred tax assets [Member]
Deferred tax assets -
Total - deferred tax assets	42,000,000	63,000,000
Alabama Power [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	4,419,000,000	4,205,000,000
Deferred tax assets -
Total - deferred tax assets	1,040,000,000	979,000,000
Total deferred tax liabilities, net	3,379,000,000	3,226,000,000
Portion included in current assets/(liabilities), net	25,000,000	31,000,000
Accumulated deferred income taxes	3,404,000,000	3,257,000,000
Alabama Power [Member] | Accelerated depreciation [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	2,989,000,000	2,820,000,000
Alabama Power [Member] | Storm reserve [Member]
Deferred tax assets -
Total - deferred tax assets	34,000,000	38,000,000
Alabama Power [Member] | Unbilled revenues [Member]
Deferred tax assets -
Total - deferred tax assets	39,000,000	38,000,000
Alabama Power [Member] | Property basis differences [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	420,000,000	439,000,000
Alabama Power [Member] | Leveraged lease basis differences [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	36,000,000	33,000,000
Alabama Power [Member] | Employee benefit obligations [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	218,000,000	217,000,000
Deferred tax assets -
Total - deferred tax assets	408,000,000	373,000,000
Alabama Power [Member] | Under recovered fuel clause [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	16,000,000	26,000,000
Alabama Power [Member] | Regulatory assets associated with employee benefit obligations [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	378,000,000	343,000,000
Alabama Power [Member] | Regulatory assets associated with asset retirement obligations [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	248,000,000	233,000,000
Alabama Power [Member] | Other deferred tax liabilities [Member]
Deferred tax liabilities -
Total - deferred tax liabilities	114,000,000	94,000,000
Alabama Power [Member] | Federal effect of state deferred taxes [Member]
Deferred tax assets -
Total - deferred tax assets	194,000,000	186,000,000
Alabama Power [Member] | State effect of federal deferred taxes [Member]
Deferred tax assets -
Total - deferred tax assets	0	0
Alabama Power [Member] | Other Comprehensive Income Losses [Member]
Deferred tax assets -
Total - deferred tax assets	19,000,000	14,000,000
Alabama Power [Member] | Asset retirement obligation [Member]
Deferred tax assets -
Total - deferred tax assets	248,000,000	233,000,000
Alabama Power [Member] | Other deferred tax assets [Member]
Deferred tax assets -
Total - deferred tax assets	$ 98,000,000	$ 97,000,000