Retirement Benefits (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Pension Plans [Member] | Southern Company [Member]
Pension Plans and Postretirement Plans
Service cost	$ 64	$ 54	$ 128	$ 107
Interest cost	111	108	222	217
Expected return on plan assets	(181)	(162)	(362)	(323)
Amortization:
Prior service costs	7	7	13	13
Net (gain)/loss	54	27	108	55
Net cost	55	34	109	69
Pension Plans [Member] | Alabama Power [Member]
Pension Plans and Postretirement Plans
Service cost	15	12	30	24
Interest cost	27	26	53	52
Expected return on plan assets	(44)	(42)	(89)	(84)
Amortization:
Prior service costs	1	2	3	3
Net (gain)/loss	13	8	27	16
Net cost	12	6	24	11
Pension Plans [Member] | Georgia Power [Member]
Pension Plans and Postretirement Plans
Service cost	18	15	36	31
Interest cost	39	38	77	76
Expected return on plan assets	(63)	(56)	(126)	(113)
Amortization:
Prior service costs	2	2	5	5
Net (gain)/loss	19	10	38	20
Net cost	15	9	30	19
Pension Plans [Member] | Gulf Power [Member]
Pension Plans and Postretirement Plans
Service cost	3	1	6	4
Interest cost	5	5	10	10
Expected return on plan assets	(8)	(7)	(16)	(14)
Amortization:
Prior service costs	0	1	0	1
Net (gain)/loss	2	1	5	2
Net cost	2	1	5	3
Pension Plans [Member] | Mississippi Power [Member]
Pension Plans and Postretirement Plans
Service cost	3	2	6	5
Interest cost	6	5	11	10
Expected return on plan assets	(9)	(7)	(17)	(14)
Amortization:
Prior service costs	1	1	1	1
Net (gain)/loss	2	1	5	2
Net cost	3	2	6	4
Other Postretirement Benefits [Member] | Southern Company [Member]
Pension Plans and Postretirement Plans
Service cost	5	6	11	11
Interest cost	20	20	39	40
Expected return on plan assets	(14)	(15)	(29)	(30)
Amortization:
Prior service costs	1	1	2	2
Net (gain)/loss	4	0	9	1
Net cost	16	12	32	24
Other Postretirement Benefits [Member] | Alabama Power [Member]
Pension Plans and Postretirement Plans
Service cost	2	2	3	3
Interest cost	5	5	10	10
Expected return on plan assets	(7)	(7)	(13)	(13)
Amortization:
Prior service costs	0	1	1	2
Net (gain)/loss	1	0	1	0
Net cost	1	1	2	2
Other Postretirement Benefits [Member] | Georgia Power [Member]
Pension Plans and Postretirement Plans
Service cost	1	1	3	3
Interest cost	9	9	17	17
Expected return on plan assets	(6)	(7)	(12)	(13)
Amortization:
Prior service costs	0	0	0	0
Net (gain)/loss	3	1	6	1
Net cost	7	4	14	8
Other Postretirement Benefits [Member] | Gulf Power [Member]
Pension Plans and Postretirement Plans
Service cost	0	1	0	1
Interest cost	1	1	2	2
Expected return on plan assets	(1)	(1)	(1)	(1)
Amortization:
Prior service costs	0	0	0	0
Net (gain)/loss	0	0	0	0
Net cost	0	1	1	2
Other Postretirement Benefits [Member] | Mississippi Power [Member]
Pension Plans and Postretirement Plans
Service cost	1	1	1	1
Interest cost	1	1	2	2
Expected return on plan assets	(1)	(1)	(1)	(1)
Amortization:
Prior service costs	0	0	0	0
Net (gain)/loss	0	0	0	0
Net cost	$ 1	$ 1	$ 2	$ 2