Retirement Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Pension Plans [Member]
Pension Plans and Postretirement Plans
Service cost	$ 58	$ 49	$ 116	$ 99
Interest cost	97	99	194	197
Expected return on plan assets	(150)	(146)	(301)	(291)
Amortization:
Prior service costs	6	8	13	15
Net (gain)/loss	50	23	100	47
Net cost	61	33	122	67
Pension Plans [Member] | Alabama Power [Member]
Pension Plans and Postretirement Plans
Service cost	14	11	27	22
Interest cost	23	24	46	47
Expected return on plan assets	(39)	(41)	(78)	(81)
Amortization:
Prior service costs	1	1	3	3
Net (gain)/loss	13	6	26	12
Net cost	12	1	24	3
Pension Plans [Member] | Georgia Power [Member]
Pension Plans and Postretirement Plans
Service cost	18	15	35	30
Interest cost	35	36	69	71
Expected return on plan assets	(53)	(55)	(106)	(110)
Amortization:
Prior service costs	2	3	5	6
Net (gain)/loss	18	8	37	16
Net cost	20	7	40	13
Pension Plans [Member] | Gulf Power [Member]
Pension Plans and Postretirement Plans
Service cost	2	3	5	5
Interest cost	5	4	9	8
Expected return on plan assets	(7)	(7)	(13)	(13)
Amortization:
Prior service costs	1	1	1	1
Net (gain)/loss	2	1	4	2
Net cost	3	2	6	3
Pension Plans [Member] | Mississippi Power [Member]
Pension Plans and Postretirement Plans
Service cost	2	3	5	5
Interest cost	4	4	9	9
Expected return on plan assets	(6)	(6)	(13)	(12)
Amortization:
Prior service costs	0	1	0	1
Net (gain)/loss	3	0	5	1
Net cost	3	2	6	4
Other Postretirement Benefits [Member]
Pension Plans and Postretirement Plans
Service cost	6	6	12	11
Interest cost	18	21	37	42
Expected return on plan assets	(14)	(15)	(28)	(30)
Amortization:
Transition obligation	1	3	2	5
Prior service costs	1	1	2	2
Net (gain)/loss	3	1	6	3
Net cost	15	17	31	33
Other Postretirement Benefits [Member] | Alabama Power [Member]
Pension Plans and Postretirement Plans
Service cost	1	2	3	3
Interest cost	4	6	9	11
Expected return on plan assets	(6)	(6)	(12)	(12)
Amortization:
Transition obligation	0	0	0	1
Prior service costs	1	1	2	2
Net (gain)/loss	1	0	1	0
Net cost	1	3	3	5
Other Postretirement Benefits [Member] | Georgia Power [Member]
Pension Plans and Postretirement Plans
Service cost	1	2	3	3
Interest cost	8	10	16	19
Expected return on plan assets	(6)	(7)	(12)	(14)
Amortization:
Transition obligation	1	1	2	3
Prior service costs	0	0	0	0
Net (gain)/loss	2	1	4	2
Net cost	6	7	13	13
Other Postretirement Benefits [Member] | Gulf Power [Member]
Pension Plans and Postretirement Plans
Service cost	1	1	1	1
Interest cost	0	1	1	2
Expected return on plan assets	0	(1)	0	(1)
Amortization:
Transition obligation	0	0	0	0
Prior service costs	0	0	0	0
Net (gain)/loss	0	0	0	0
Net cost	1	1	2	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:
Transition obligation	0	0	0	0
Prior service costs	0	0	0	0
Net (gain)/loss	0	0	0	0
Net cost	$ 1	$ 1	$ 2	$ 2