Retirement Benefits - Actuarial Assumptions 3 (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Effect of one percent annual increase or decrease in the assumed medical care cost on APBO and the service and interest cost components
1 Percent increase on benefit obligation	$ 126,000
1 Percent decrease on benefit obligation	(106,000)
1 Percent increase on service and interest costs	7,000
1 Percent decrease on service and interest costs	(6,000)
Gulf Power [Member]
Effect of one percent annual increase or decrease in the assumed medical care cost on APBO and the service and interest cost components
1 Percent increase on benefit obligation	3,399
1 Percent decrease on benefit obligation	(2,897)
1 Percent increase on service and interest costs	198
1 Percent decrease on service and interest costs	(169)
Mississippi Power [Member]
Effect of one percent annual increase or decrease in the assumed medical care cost on APBO and the service and interest cost components
1 Percent increase on benefit obligation	6,000
1 Percent decrease on benefit obligation	(5,099)
1 Percent increase on service and interest costs	316
1 Percent decrease on service and interest costs	(268)
Georgia Power [Member]
Effect of one percent annual increase or decrease in the assumed medical care cost on APBO and the service and interest cost components
1 Percent increase on benefit obligation	61,000
1 Percent decrease on benefit obligation	(52,000)
1 Percent increase on service and interest costs	3,000
1 Percent decrease on service and interest costs	(3,000)
Alabama Power [Member]
Effect of one percent annual increase or decrease in the assumed medical care cost on APBO and the service and interest cost components
1 Percent increase on benefit obligation	32,000
1 Percent decrease on benefit obligation	(27,000)
1 Percent increase on service and interest costs	2,000
1 Percent decrease on service and interest costs	$ (1,000)