Retirement Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Pension Plans [Member]
Pension Plans and Postretirement Plans
Service cost	$ 53	$ 58
Interest cost	109	97
Expected return on plan assets	(161)	(151)
Amortization:
Prior service costs	6	7
Net (gain)/loss	28	50
Net cost	35	61
Pension Plans [Member] | Alabama Power [Member]
Pension Plans and Postretirement Plans
Service cost	12	13
Interest cost	26	23
Expected return on plan assets	(42)	(39)
Amortization:
Prior service costs	1	2
Net (gain)/loss	8	13
Net cost	5	12
Pension Plans [Member] | Georgia Power [Member]
Pension Plans and Postretirement Plans
Service cost	16	17
Interest cost	38	34
Expected return on plan assets	(57)	(53)
Amortization:
Prior service costs	3	3
Net (gain)/loss	10	19
Net cost	10	20
Pension Plans [Member] | Gulf Power [Member]
Pension Plans and Postretirement Plans
Service cost	3	3
Interest cost	5	4
Expected return on plan assets	(7)	(6)
Amortization:
Prior service costs	0	0
Net (gain)/loss	1	2
Net cost	2	3
Pension Plans [Member] | Mississippi Power [Member]
Pension Plans and Postretirement Plans
Service cost	3	3
Interest cost	5	5
Expected return on plan assets	(7)	(7)
Amortization:
Prior service costs	0	0
Net (gain)/loss	1	2
Net cost	2	3
Other Postretirement Benefits [Member]
Pension Plans and Postretirement Plans
Service cost	5	6
Interest cost	20	19
Expected return on plan assets	(15)	(14)
Amortization:
Transition obligation		1
Prior service costs	1	1
Net (gain)/loss	1	3
Net cost	12	16
Other Postretirement Benefits [Member] | Alabama Power [Member]
Pension Plans and Postretirement Plans
Service cost	1	2
Interest cost	5	5
Expected return on plan assets	(6)	(6)
Amortization:
Transition obligation		0
Prior service costs	1	1
Net (gain)/loss	0	0
Net cost	1	2
Other Postretirement Benefits [Member] | Georgia Power [Member]
Pension Plans and Postretirement Plans
Service cost	2	2
Interest cost	8	8
Expected return on plan assets	(6)	(6)
Amortization:
Transition obligation		1
Prior service costs	0	0
Net (gain)/loss	0	2
Net cost	4	7
Other Postretirement Benefits [Member] | Gulf Power [Member]
Pension Plans and Postretirement Plans
Service cost	0	0
Interest cost	1	1
Expected return on plan assets	0	0
Amortization:
Transition obligation		0
Prior service costs	0	0
Net (gain)/loss	0	0
Net cost	1	1
Other Postretirement Benefits [Member] | Mississippi Power [Member]
Pension Plans and Postretirement Plans
Service cost	0	0
Interest cost	1	1
Expected return on plan assets	0	0
Amortization:
Transition obligation		0
Prior service costs	0	0
Net (gain)/loss	0	0
Net cost	$ 1	$ 1