Retirement Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Pension Plans [Member]
Pension Plans and Postretirement Plans
Service cost	$ 49	$ 46	$ 99	$ 92
Interest cost	99	97	197	195
Expected return on plan assets	(146)	(152)	(291)	(304)
Net amortization	31	13	62	26
Net cost (income)	33	4	67	9
Pension Plans [Member] | Alabama Power [Member]
Pension Plans and Postretirement Plans
Service cost	11	10	22	21
Interest cost	24	24	47	48
Expected return on plan assets	(41)	(43)	(81)	(86)
Net amortization	7	4	15	7
Net cost (income)	1	(5)	3	(10)
Pension Plans [Member] | Georgia Power [Member]
Pension Plans and Postretirement Plans
Service cost	15	15	30	29
Interest cost	36	36	71	72
Expected return on plan assets	(55)	(58)	(110)	(117)
Net amortization	11	4	22	9
Net cost (income)	7	(3)	13	(7)
Pension Plans [Member] | Gulf Power [Member]
Pension Plans and Postretirement Plans
Service cost	3	2	5	4
Interest cost	4	5	8	9
Expected return on plan assets	(7)	(7)	(13)	(14)
Net amortization	2		3	1
Net cost (income)	2		3
Pension Plans [Member] | Mississippi Power [Member]
Pension Plans and Postretirement Plans
Service cost	3	2	5	4
Interest cost	4	5	9	9
Expected return on plan assets	(6)	(6)	(12)	(12)
Net amortization	1		2	1
Net cost (income)	2	1	4	2
Other Postretirement Benefits [Member]
Pension Plans and Postretirement Plans
Service cost	6	5	11	10
Interest cost	21	23	42	46
Expected return on plan assets	(15)	(16)	(30)	(32)
Net amortization	5	5	10	10
Net cost (income)	17	17	33	34
Other Postretirement Benefits [Member] | Alabama Power [Member]
Pension Plans and Postretirement Plans
Service cost	2	2	3	3
Interest cost	6	6	11	12
Expected return on plan assets	(6)	(7)	(12)	(13)
Net amortization	1	1	3	3
Net cost (income)	3	2	5	5
Other Postretirement Benefits [Member] | Georgia Power [Member]
Pension Plans and Postretirement Plans
Service cost	2	2	3	4
Interest cost	10	10	19	20
Expected return on plan assets	(7)	(7)	(14)	(15)
Net amortization	2	2	5	5
Net cost (income)	7	7	13	14
Other Postretirement Benefits [Member] | Gulf 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)
Net cost (income)	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)
Net cost (income)	$ 1	$ 1	$ 2	$ 2