Retirement Benefits - Components of Net Periodic Benefit Cost and Estimated Future Benefit Payments (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Other Postretirement Benefits [Member]
Components of net periodic
Service cost	$ 24,000	$ 21,000	$ 21,000
Interest cost	74,000	85,000	92,000
Expected return on plan assets	(56,000)	(60,000)	(64,000)
Net amortization	21,000	20,000	20,000
Net periodic benefit cost	63,000	66,000	69,000
Benefit Payments
Benefit Payments, 2014	110,000
Benefit Payments, 2015	115,000
Benefit Payments, 2016	120,000
Benefit Payments, 2017	124,000
Benefit Payments, 2018	130,000
Benefit Payments, 2019 to 2023	654,000
Subsidy Receipts
Subsidy Receipts, 2014	(9,000)
Subsidy Receipts, 2015	(10,000)
Subsidy Receipts, 2016	(11,000)
Subsidy Receipts, 2017	(13,000)
Subsidy Receipts, 2018	(14,000)
Subsidy Receipts, 2019 to 2023	(75,000)
Benefit Payments and Subsidy Receipts, Total
Benefit Payments and Subsidy Receipts, 2014	101,000
Benefit Payments and Subsidy Receipts, 2015	105,000
Benefit Payments and Subsidy Receipts, 2016	109,000
Benefit Payments and Subsidy Receipts, 2017	111,000
Benefit Payments and Subsidy Receipts, 2018	116,000
Benefit Payments and Subsidy Receipts, 2019 to 2023	579,000
Pension Plans [Member]
Components of net periodic
Service cost	232,000	198,000	184,000
Interest cost	389,000	393,000	389,000
Expected return on plan assets	(603,000)	(581,000)	(607,000)
Recognized net (gain) loss	200,000	95,000	21,000
Net amortization	27,000	30,000	32,000
Net periodic benefit cost	245,000	135,000	19,000
Benefit Payments
Benefit Payments, 2014	399,000
Benefit Payments, 2015	422,000
Benefit Payments, 2016	446,000
Benefit Payments, 2017	471,000
Benefit Payments, 2018	492,000
Benefit Payments, 2019 to 2023	2,795,000
Alabama Power [Member] | Other Postretirement Benefits [Member]
Components of net periodic
Service cost	6,000	5,000	5,000
Interest cost	19,000	22,000	24,000
Expected return on plan assets	(23,000)	(23,000)	(25,000)
Net amortization	5,000	6,000	7,000
Net periodic benefit cost	7,000	10,000	11,000
Benefit Payments
Benefit Payments, 2014	30,000
Benefit Payments, 2015	31,000
Benefit Payments, 2016	31,000
Benefit Payments, 2017	33,000
Benefit Payments, 2018	33,000
Benefit Payments, 2019 to 2023	164,000
Subsidy Receipts
Subsidy Receipts, 2014	(3,000)
Subsidy Receipts, 2015	(3,000)
Subsidy Receipts, 2016	(3,000)
Subsidy Receipts, 2017	(4,000)
Subsidy Receipts, 2018	(4,000)
Subsidy Receipts, 2019 to 2023	(22,000)
Benefit Payments and Subsidy Receipts, Total
Benefit Payments and Subsidy Receipts, 2014	27,000
Benefit Payments and Subsidy Receipts, 2015	28,000
Benefit Payments and Subsidy Receipts, 2016	28,000
Benefit Payments and Subsidy Receipts, 2017	29,000
Benefit Payments and Subsidy Receipts, 2018	29,000
Benefit Payments and Subsidy Receipts, 2019 to 2023	142,000
Alabama Power [Member] | Pension Plans [Member]
Components of net periodic
Service cost	52,000	44,000	43,000
Interest cost	93,000	94,000	96,000
Expected return on plan assets	(157,000)	(162,000)	(173,000)
Recognized net (gain) loss	52,000	23,000	4,000
Net amortization	7,000	7,000	9,000
Net periodic benefit cost	47,000	6,000	(21,000)
Benefit Payments
Benefit Payments, 2014	104,000
Benefit Payments, 2015	108,000
Benefit Payments, 2016	113,000
Benefit Payments, 2017	118,000
Benefit Payments, 2018	122,000
Benefit Payments, 2019 to 2023	669,000
Georgia Power [Member] | Other Postretirement Benefits [Member]
Components of net periodic
Service cost	7,000	7,000	7,000
Interest cost	31,000	37,000	41,000
Expected return on plan assets	(24,000)	(29,000)	(30,000)
Net amortization	12,000	10,000	11,000
Net periodic benefit cost	26,000	25,000	29,000
Benefit Payments
Benefit Payments, 2014	49,000
Benefit Payments, 2015	50,000
Benefit Payments, 2016	53,000
Benefit Payments, 2017	54,000
Benefit Payments, 2018	58,000
Benefit Payments, 2019 to 2023	287,000
Subsidy Receipts
Subsidy Receipts, 2014	(4,000)
Subsidy Receipts, 2015	(4,000)
Subsidy Receipts, 2016	(5,000)
Subsidy Receipts, 2017	(5,000)
Subsidy Receipts, 2018	(6,000)
Subsidy Receipts, 2019 to 2023	(30,000)
Benefit Payments and Subsidy Receipts, Total
Benefit Payments and Subsidy Receipts, 2014	45,000
Benefit Payments and Subsidy Receipts, 2015	46,000
Benefit Payments and Subsidy Receipts, 2016	48,000
Benefit Payments and Subsidy Receipts, 2017	49,000
Benefit Payments and Subsidy Receipts, 2018	52,000
Benefit Payments and Subsidy Receipts, 2019 to 2023	257,000
Georgia Power [Member] | Pension Plans [Member]
Components of net periodic
Service cost	69,000	60,000	57,000
Interest cost	138,000	141,000	144,000
Expected return on plan assets	(212,000)	(221,000)	(234,000)
Recognized net (gain) loss	74,000	33,000	6,000
Net amortization	10,000	12,000	12,000
Net periodic benefit cost	79,000	25,000	(15,000)
Benefit Payments
Benefit Payments, 2014	154,000
Benefit Payments, 2015	161,000
Benefit Payments, 2016	167,000
Benefit Payments, 2017	175,000
Benefit Payments, 2018	181,000
Benefit Payments, 2019 to 2023	995,000
Gulf Power [Member]
Components of net periodic
Service cost	11,128	9,101	8,431
Interest cost	17,321	17,199	17,074
Expected return on plan assets	(26,435)	(25,932)	(27,232)
Recognized net (gain) loss	8,385	3,913	512
Net amortization	1,164	1,262	1,262
Net periodic benefit cost	11,563	5,543	47
Gulf Power [Member] | Other Postretirement Benefits [Member]
Components of net periodic
Service cost	1,355	1,167	1,132
Interest cost	2,982	3,367	3,658
Expected return on plan assets	(1,238)	(1,311)	(1,445)
Net amortization	186	379	396
Net periodic benefit cost	3,285	3,602	3,741
Benefit Payments
Benefit Payments, 2014	4,447
Benefit Payments, 2015	4,630
Benefit Payments, 2016	4,856
Benefit Payments, 2017	4,994
Benefit Payments, 2018	5,168
Benefit Payments, 2019 to 2023	26,272
Subsidy Receipts
Subsidy Receipts, 2014	(409)
Subsidy Receipts, 2015	(456)
Subsidy Receipts, 2016	(504)
Subsidy Receipts, 2017	(557)
Subsidy Receipts, 2018	(611)
Subsidy Receipts, 2019 to 2023	(3,251)
Benefit Payments and Subsidy Receipts, Total
Benefit Payments and Subsidy Receipts, 2014	4,038
Benefit Payments and Subsidy Receipts, 2015	4,174
Benefit Payments and Subsidy Receipts, 2016	4,352
Benefit Payments and Subsidy Receipts, 2017	4,437
Benefit Payments and Subsidy Receipts, 2018	4,557
Benefit Payments and Subsidy Receipts, 2019 to 2023	23,021
Gulf Power [Member] | Pension Plans [Member]
Components of net periodic
Service cost	11,128	9,101
Interest cost	17,321	17,199
Benefit Payments
Benefit Payments, 2014	16,548
Benefit Payments, 2015	17,440
Benefit Payments, 2016	18,405
Benefit Payments, 2017	19,649
Benefit Payments, 2018	20,681
Benefit Payments, 2019 to 2023	121,864
Mississippi Power [Member]
Components of net periodic
Service cost	11,067	9,416	8,838
Interest cost	18,062	18,019	17,827
Expected return on plan assets	(26,849)	(24,121)	(25,166)
Recognized net (gain) loss	9,461	4,100	1,114
Net amortization	1,143	1,309	1,309
Net periodic benefit cost	12,884	8,723	3,922
Mississippi Power [Member] | Other Postretirement Benefits [Member]
Components of net periodic
Service cost	1,151	1,038	1,012
Interest cost	3,619	4,155	4,292
Expected return on plan assets	(1,472)	(1,552)	(1,763)
Net amortization	471	470	274
Net periodic benefit cost	3,769	4,111	3,815
Benefit Payments
Benefit Payments, 2014	5,051
Benefit Payments, 2015	5,335
Benefit Payments, 2016	5,569
Benefit Payments, 2017	5,849
Benefit Payments, 2018	6,091
Benefit Payments, 2019 to 2023	32,600
Subsidy Receipts
Subsidy Receipts, 2014	(526)
Subsidy Receipts, 2015	(577)
Subsidy Receipts, 2016	(632)
Subsidy Receipts, 2017	(689)
Subsidy Receipts, 2018	(748)
Subsidy Receipts, 2019 to 2023	(3,793)
Benefit Payments and Subsidy Receipts, Total
Benefit Payments and Subsidy Receipts, 2014	4,525
Benefit Payments and Subsidy Receipts, 2015	4,758
Benefit Payments and Subsidy Receipts, 2016	4,937
Benefit Payments and Subsidy Receipts, 2017	5,160
Benefit Payments and Subsidy Receipts, 2018	5,343
Benefit Payments and Subsidy Receipts, 2019 to 2023	28,807
Mississippi Power [Member] | Pension Plans [Member]
Components of net periodic
Service cost	11,067	9,416
Interest cost	18,062	18,019
Benefit Payments
Benefit Payments, 2014	17,245
Benefit Payments, 2015	18,076
Benefit Payments, 2016	18,993
Benefit Payments, 2017	20,172
Benefit Payments, 2018	21,237
Benefit Payments, 2019 to 2023	$ 124,728