Retirement Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Pension Plans [Member]
Pension Plans and Postretirement Plans
Service cost	$ 58	$ 49	$ 174	$ 148
Interest cost	97	98	291	295
Expected return on plan assets	(151)	(145)	(452)	(436)
Amortization:
Prior service costs	7	8	20	23
Net (gain)/loss	50	24	150	71
Net cost	61	34	183	101
Pension Plans [Member] | Alabama Power [Member]
Pension Plans and Postretirement Plans
Service cost	12	11	39	33
Interest cost	23	23	69	70
Expected return on plan assets	(39)	(40)	(117)	(121)
Amortization:
Prior service costs	2	2	5	5
Net (gain)/loss	13	6	39	18
Net cost	11	2	35	5
Pension Plans [Member] | Georgia Power [Member]
Pension Plans and Postretirement Plans
Service cost	17	15	52	45
Interest cost	35	35	104	106
Expected return on plan assets	(54)	(56)	(160)	(166)
Amortization:
Prior service costs	3	3	8	9
Net (gain)/loss	19	9	56	25
Net cost	20	6	60	19
Pension Plans [Member] | Gulf Power [Member]
Pension Plans and Postretirement Plans
Service cost	3	2	8	7
Interest cost	4	5	13	13
Expected return on plan assets	(6)	(7)	(19)	(20)
Amortization:
Prior service costs	0	0	1	1
Net (gain)/loss	2	1	6	3
Net cost	3	1	9	4
Pension Plans [Member] | Mississippi Power [Member]
Pension Plans and Postretirement Plans
Service cost	3	2	8	7
Interest cost	5	5	14	14
Expected return on plan assets	(7)	(6)	(20)	(18)
Amortization:
Prior service costs	1	0	1	1
Net (gain)/loss	2	2	7	3
Net cost	4	3	10	7
Other Postretirement Benefits [Member]
Pension Plans and Postretirement Plans
Service cost	6	5	18	16
Interest cost	18	21	55	63
Expected return on plan assets	(14)	(15)	(42)	(45)
Amortization:
Transition obligation	2	2	4	7
Prior service costs	1	1	3	3
Net (gain)/loss	3	2	9	5
Net cost	16	16	47	49
Other Postretirement Benefits [Member] | Alabama Power [Member]
Pension Plans and Postretirement Plans
Service cost	2	1	5	4
Interest cost	5	6	14	17
Expected return on plan assets	(6)	(6)	(18)	(18)
Amortization:
Transition obligation	0	0	0	1
Prior service costs	1	1	3	3
Net (gain)/loss	0	0	1	0
Net cost	2	2	5	7
Other Postretirement Benefits [Member] | Georgia Power [Member]
Pension Plans and Postretirement Plans
Service cost	3	2	6	5
Interest cost	8	8	24	27
Expected return on plan assets	(7)	(7)	(19)	(21)
Amortization:
Transition obligation	1	2	3	5
Prior service costs	0	0	0	0
Net (gain)/loss	2	1	6	3
Net cost	7	6	20	19
Other Postretirement Benefits [Member] | Gulf Power [Member]
Pension Plans and Postretirement Plans
Service cost	0	0	1	1
Interest cost	1	1	2	3
Expected return on plan assets	(1)	0	(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	0	1	2	3
Other Postretirement Benefits [Member] | Mississippi Power [Member]
Pension Plans and Postretirement Plans
Service cost	0	0	1	1
Interest cost	1	1	3	3
Expected return on plan assets	0	0	(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	$ 3	$ 3