Retirement Benefits - Amounts Recognized in Balance Sheets and Amounts in AOCI (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Amounts recognized in the consolidated balance sheets related to company's pension plans
Prepaid pension costs	$ 419,000,000	$ 0
Other regulatory assets, deferred	2,557,000,000	4,032,000,000
Other current liabilities	(347,000,000)	(557,000,000)
Other regulatory liabilities, deferred	(475,000,000)	(289,000,000)
Employee benefit obligations	(1,461,000,000)	(2,540,000,000)
Accumulated OCI	(75,000,000)	(123,000,000)
Amounts related to defined benefit pension Plans that had not yet been recognized in net periodic pension cost along with estimated amortization
Net Regulatory Assets	2,624,000,000	4,322,000,000
Pension Plans [Member]
Amounts recognized in the consolidated balance sheets related to company's pension plans
Prepaid pension costs	419,000,000	0
Other regulatory assets, deferred	1,651,000,000	3,013,000,000
Other current liabilities	(40,000,000)	(37,000,000)
Employee benefit obligations	(509,000,000)	(1,312,000,000)
Accumulated OCI	64,000,000	125,000,000
Amounts related to defined benefit pension Plans that had not yet been recognized in net periodic pension cost along with estimated amortization
Prior Service Cost	80,000,000	107,000,000
Net (Gain) Loss	1,634,000,000	3,031,000,000
Prior Service Cost, Estimated	26,000,000
Net (Gain) Loss, Estimated	110,000,000
Pension Plans [Member] | Accumulated Other Comprehensive Income (Loss)
Amounts related to defined benefit pension Plans that had not yet been recognized in net periodic pension cost along with estimated amortization
Prior Service Cost	5,000,000	7,000,000
Net (Gain) Loss	59,000,000	118,000,000
Prior Service Cost, Estimated	1,000,000
Net (Gain) Loss, Estimated	4,000,000
Pension Plans [Member] | Regulatory Assets [Member]
Amounts related to defined benefit pension Plans that had not yet been recognized in net periodic pension cost along with estimated amortization
Prior Service Cost	75,000,000	100,000,000
Net (Gain) Loss	1,575,000,000	2,913,000,000
Prior Service Cost, Estimated	25,000,000
Net (Gain) Loss, Estimated	106,000,000
Other Postretirement Benefits [Member]
Amounts recognized in the consolidated balance sheets related to company's pension plans
Other regulatory assets, deferred	109,000,000	360,000,000
Other current liabilities	(4,000,000)	(3,000,000)
Other regulatory liabilities, deferred	(36,000,000)	0
Employee benefit obligations	(777,000,000)	(1,048,000,000)
Accumulated OCI	1,000,000	7,000,000
Amounts related to defined benefit pension Plans that had not yet been recognized in net periodic pension cost along with estimated amortization
Prior Service Cost	9,000,000	13,000,000
Net (Gain) Loss	65,000,000	349,000,000
Transition Obligation	0	5,000,000
Prior Service Cost, Estimated	4,000,000
Net (Gain) Loss, Estimated	2,000,000
Transition Obligation, Estimated	0
Other Postretirement Benefits [Member] | Accumulated Other Comprehensive Income (Loss)
Amounts related to defined benefit pension Plans that had not yet been recognized in net periodic pension cost along with estimated amortization
Prior Service Cost	0	0
Net (Gain) Loss	1,000,000	7,000,000
Transition Obligation	0	0
Prior Service Cost, Estimated	0
Net (Gain) Loss, Estimated	0
Transition Obligation, Estimated	0
Other Postretirement Benefits [Member] | Regulatory Assets [Member]
Amounts related to defined benefit pension Plans that had not yet been recognized in net periodic pension cost along with estimated amortization
Prior Service Cost	9,000,000	13,000,000
Net (Gain) Loss	64,000,000	342,000,000
Transition Obligation	0	5,000,000
Prior Service Cost, Estimated	4,000,000
Net (Gain) Loss, Estimated	2,000,000
Transition Obligation, Estimated	0
Alabama Power [Member]
Amounts recognized in the consolidated balance sheets related to company's pension plans
Prepaid pension costs	276,000,000	0
Other regulatory assets, deferred	692,000,000	1,083,000,000
Other current liabilities	(41,000,000)	(52,000,000)
Other regulatory liabilities, deferred	(259,000,000)	(183,000,000)
Employee benefit obligations	(195,000,000)	(321,000,000)
Accumulated OCI	(26,000,000)	(27,000,000)
Amounts related to defined benefit pension Plans that had not yet been recognized in net periodic pension cost along with estimated amortization
Net Regulatory Assets	92,000,000	703,000,000
Alabama Power [Member] | Pension Plans [Member]
Amounts recognized in the consolidated balance sheets related to company's pension plans
Prepaid pension costs	276,000,000	0
Other regulatory assets, deferred	476,000,000	822,000,000
Other current liabilities	(9,000,000)	(8,000,000)
Employee benefit obligations	(101,000,000)	(133,000,000)
Alabama Power [Member] | Pension Plans [Member] | Regulatory Assets [Member]
Amounts related to defined benefit pension Plans that had not yet been recognized in net periodic pension cost along with estimated amortization
Prior Service Cost	19,000,000	26,000,000
Net (Gain) Loss	457,000,000	796,000,000
Prior Service Cost, Estimated	7,000,000
Net (Gain) Loss, Estimated	(31,000,000)
Alabama Power [Member] | Other Postretirement Benefits [Member]
Amounts recognized in the consolidated balance sheets related to company's pension plans
Other regulatory assets, deferred	6,000,000	89,000,000
Other regulatory liabilities, deferred	(21,000,000)	0
Employee benefit obligations	(42,000,000)	(147,000,000)
Alabama Power [Member] | Other Postretirement Benefits [Member] | Regulatory Assets [Member]
Amounts recognized in the consolidated balance sheets related to company's pension plans
Other regulatory assets, deferred	(15,000,000)	89,000,000
Amounts related to defined benefit pension Plans that had not yet been recognized in net periodic pension cost along with estimated amortization
Prior Service Cost	19,000,000	22,000,000
Net (Gain) Loss	(34,000,000)	67,000,000
Prior Service Cost, Estimated	4,000,000
Net (Gain) Loss, Estimated	0
Georgia Power [Member]
Amounts recognized in the consolidated balance sheets related to company's pension plans
Prepaid pension costs	118,000,000	0
Other regulatory assets, deferred	1,152,000,000	1,798,000,000
Other current liabilities	(122,000,000)	(146,000,000)
Employee benefit obligations	(542,000,000)	(950,000,000)
Accumulated OCI	(5,000,000)	(7,000,000)
Amounts related to defined benefit pension Plans that had not yet been recognized in net periodic pension cost along with estimated amortization
Net Regulatory Assets	1,886,000,000	2,471,000,000
Georgia Power [Member] | Pension Plans [Member]
Amounts recognized in the consolidated balance sheets related to company's pension plans
Prepaid pension costs	118,000,000	0
Other regulatory assets, deferred	610,000,000	1,132,000,000
Other current liabilities	(12,000,000)	(11,000,000)
Employee benefit obligations	(137,000,000)	(474,000,000)
Amounts related to defined benefit pension Plans that had not yet been recognized in net periodic pension cost along with estimated amortization
Prior Service Cost	26,000,000	37,000,000
Net (Gain) Loss	584,000,000	1,095,000,000
Prior Service Cost, Estimated	10,000,000
Net (Gain) Loss, Estimated	41,000,000
Georgia Power [Member] | Other Postretirement Benefits [Member]
Amounts recognized in the consolidated balance sheets related to company's pension plans
Other regulatory assets, deferred	69,000,000	187,000,000
Employee benefit obligations	(316,000,000)	(418,000,000)
Amounts related to defined benefit pension Plans that had not yet been recognized in net periodic pension cost along with estimated amortization
Prior Service Cost	(4,000,000)	(4,000,000)
Net (Gain) Loss	73,000,000	186,000,000
Transition Obligation	0	5,000,000
Prior Service Cost, Estimated	0
Net (Gain) Loss, Estimated	2,000,000
Transition Obligation, Estimated	0
Gulf Power [Member]
Amounts recognized in the consolidated balance sheets related to company's pension plans
Prepaid pension costs	11,533,000	0
Other regulatory assets, deferred	340,415,000	372,294,000
Other current liabilities	(22,972,000)	(19,930,000)
Other regulatory liabilities, deferred	(56,051,000)	(47,863,000)
Employee benefit obligations	(76,338,000)	(126,871,000)
Accumulated OCI	(1,109,000)	(1,581,000)
Amounts related to defined benefit pension Plans that had not yet been recognized in net periodic pension cost along with estimated amortization
Net Regulatory Assets	160,224,000	171,985,000
Gulf Power [Member] | Pension Plans [Member]
Amounts recognized in the consolidated balance sheets related to company's pension plans
Prepaid pension costs	11,533,000	0
Other regulatory assets, deferred	75,280,000	139,261,000
Other current liabilities	(1,183,000)	(855,000)
Employee benefit obligations	(20,039,000)	(62,386,000)
Amounts related to defined benefit pension Plans that had not yet been recognized in net periodic pension cost along with estimated amortization
Prior Service Cost	4,401,000	5,565,000
Net (Gain) Loss	70,879,000	133,696,000
Prior Service Cost, Estimated	1,115,000
Net (Gain) Loss, Estimated	4,559,000
Gulf Power [Member] | Other Postretirement Benefits [Member]
Amounts recognized in the consolidated balance sheets related to company's pension plans
Other regulatory assets, deferred	0	2,169,000
Other current liabilities	(687,000)	(661,000)
Other regulatory liabilities, deferred	(6,984,000)	0
Employee benefit obligations	(50,418,000)	(58,507,000)
Gulf Power [Member] | Other Postretirement Benefits [Member] | Regulatory Assets [Member]
Amounts recognized in the consolidated balance sheets related to company's pension plans
Other regulatory assets, deferred	(6,984,000)	2,169,000
Amounts related to defined benefit pension Plans that had not yet been recognized in net periodic pension cost along with estimated amortization
Prior Service Cost	138,000	324,000
Net (Gain) Loss	(7,122,000)	1,845,000
Prior Service Cost, Estimated	186,000
Net (Gain) Loss, Estimated	(24,000)
Mississippi Power [Member]
Amounts recognized in the consolidated balance sheets related to company's pension plans
Other regulatory assets, deferred	200,620,000	236,225,000
Other current liabilities	(21,413,000)	(31,882,000)
Other regulatory liabilities, deferred	(140,880,000)	(56,984,000)
Employee benefit obligations	(94,430,000)	(157,421,000)
Accumulated OCI	(7,864,000)	(8,713,000)
Amounts related to defined benefit pension Plans that had not yet been recognized in net periodic pension cost along with estimated amortization
Net Regulatory Assets	66,604,000	147,469,000
Mississippi Power [Member] | Pension Plans [Member]
Amounts recognized in the consolidated balance sheets related to company's pension plans
Prepaid pension costs	5,698,000	0
Other regulatory assets, deferred	77,572,000	146,838,000
Other current liabilities	(2,134,000)	(2,087,000)
Employee benefit obligations	(25,556,000)	(78,717,000)
Amounts related to defined benefit pension Plans that had not yet been recognized in net periodic pension cost along with estimated amortization
Prior Service Cost	4,118,000	5,261,000
Net (Gain) Loss	73,454,000	141,577,000
Prior Service Cost, Estimated	1,088,000
Net (Gain) Loss, Estimated	4,937,000
Mississippi Power [Member] | Other Postretirement Benefits [Member]
Amounts recognized in the consolidated balance sheets related to company's pension plans
Other regulatory assets, deferred	5,227,000	15,454,000
Other regulatory liabilities, deferred	(3,111,000)	0
Employee benefit obligations	(57,663,000)	(69,793,000)
Amounts related to defined benefit pension Plans that had not yet been recognized in net periodic pension cost along with estimated amortization
Prior Service Cost	(2,311,000)	(2,498,000)
Net (Gain) Loss	4,427,000	17,952,000
Prior Service Cost, Estimated	(188,000)
Net (Gain) Loss, Estimated	0
Net Regulatory Assets	$ 2,116,000	$ 15,454,000