Retirement Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Pension Plans [Member] | Southern Company [Member]
Pension Plans and Postretirement Plans
Service cost	$ 53	$ 58	$ 160	$ 174
Interest cost	109	97	326	291
Expected return on plan assets	(161)	(151)	(484)	(452)
Amortization:
Prior service costs	6	7	19	20
Net (gain)/loss	28	50	83	150
Net cost	35	61	104	183
Pension Plans [Member] | Alabama Power [Member]
Pension Plans and Postretirement Plans
Service cost	12	12	36	39
Interest cost	26	23	78	69
Expected return on plan assets	(42)	(39)	(126)	(117)
Amortization:
Prior service costs	2	2	5	5
Net (gain)/loss	7	13	23	39
Net cost	5	11	16	35
Pension Plans [Member] | Georgia Power [Member]
Pension Plans and Postretirement Plans
Service cost	16	17	47	52
Interest cost	39	35	115	104
Expected return on plan assets	(57)	(54)	(170)	(160)
Amortization:
Prior service costs	2	3	7	8
Net (gain)/loss	10	19	30	56
Net cost	10	20	29	60
Pension Plans [Member] | Gulf Power [Member]
Pension Plans and Postretirement Plans
Service cost	4	3	8	8
Interest cost	4	4	14	13
Expected return on plan assets	(7)	(6)	(21)	(19)
Amortization:
Prior service costs	0	0	1	1
Net (gain)/loss	1	2	3	6
Net cost	2	3	5	9
Pension Plans [Member] | Mississippi Power [Member]
Pension Plans and Postretirement Plans
Service cost	3	3	8	8
Interest cost	5	5	15	14
Expected return on plan assets	(8)	(7)	(22)	(20)
Amortization:
Prior service costs	0	1	1	1
Net (gain)/loss	2	2	4	7
Net cost	2	4	6	10
Other Postretirement Benefits [Member] | Southern Company [Member]
Pension Plans and Postretirement Plans
Service cost	5	6	16	18
Interest cost	19	18	59	55
Expected return on plan assets	(14)	(14)	(44)	(42)
Amortization:
Transition obligation		2		4
Prior service costs	1	1	3	3
Net (gain)/loss	1	3	2	9
Net cost	12	16	36	47
Other Postretirement Benefits [Member] | Alabama Power [Member]
Pension Plans and Postretirement Plans
Service cost	1	2	4	5
Interest cost	5	5	15	14
Expected return on plan assets	(6)	(6)	(19)	(18)
Amortization:
Transition obligation		0		0
Prior service costs	1	1	3	3
Net (gain)/loss	0	0	0	1
Net cost	1	2	3	5
Other Postretirement Benefits [Member] | Georgia Power [Member]
Pension Plans and Postretirement Plans
Service cost	2	3	5	6
Interest cost	9	8	26	24
Expected return on plan assets	(6)	(7)	(19)	(19)
Amortization:
Transition obligation		1		3
Prior service costs	0	0	0	0
Net (gain)/loss	0	2	1	6
Net cost	5	7	13	20
Other Postretirement Benefits [Member] | Gulf Power [Member]
Pension Plans and Postretirement Plans
Service cost	0	0	1	1
Interest cost	0	1	2	2
Expected return on plan assets	0	(1)	(1)	(1)
Amortization:
Transition obligation		0		0
Prior service costs	0	0	0	0
Net (gain)/loss	0	0	0	0
Net cost	0	0	2	2
Other Postretirement Benefits [Member] | Mississippi Power [Member]
Pension Plans and Postretirement Plans
Service cost	0	0	1	1
Interest cost	0	1	2	3
Expected return on plan assets	0	0	(1)	(1)
Amortization:
Transition obligation		0		0
Prior service costs	0	0	0	0
Net (gain)/loss	0	0	0	0
Net cost	$ 0	$ 1	$ 2	$ 3