Retirement Benefits - Actuarial Assumptions 2 (Details)	12 Months Ended
	Dec. 31, 2012
Other Postretirement Benefits [Member] | Pre-65 [Member]
Weighted average medical care cost trend rates used in measuring the APBO
Initial Cost Trend Rate	8.00%
Ultimate Cost Trend Rate	5.00%
Year That Ultimate Rate Is Reached	2020
Other Postretirement Benefits [Member] | Post-65 medical [Member]
Weighted average medical care cost trend rates used in measuring the APBO
Initial Cost Trend Rate	6.00%
Ultimate Cost Trend Rate	5.00%
Year That Ultimate Rate Is Reached	2020
Other Postretirement Benefits [Member] | Post-65 prescription [Member]
Weighted average medical care cost trend rates used in measuring the APBO
Initial Cost Trend Rate	6.00%
Ultimate Cost Trend Rate	5.00%
Year That Ultimate Rate Is Reached	2020
Gulf Power [Member] | Other Postretirement Benefits [Member] | Pre-65 [Member]
Weighted average medical care cost trend rates used in measuring the APBO
Initial Cost Trend Rate	8.00%
Ultimate Cost Trend Rate	5.00%
Year That Ultimate Rate Is Reached	2020
Gulf Power [Member] | Other Postretirement Benefits [Member] | Post-65 medical [Member]
Weighted average medical care cost trend rates used in measuring the APBO
Initial Cost Trend Rate	6.00%
Ultimate Cost Trend Rate	5.00%
Year That Ultimate Rate Is Reached	2020
Gulf Power [Member] | Other Postretirement Benefits [Member] | Post-65 prescription [Member]
Weighted average medical care cost trend rates used in measuring the APBO
Initial Cost Trend Rate	6.00%
Ultimate Cost Trend Rate	5.00%
Year That Ultimate Rate Is Reached	2020
Mississippi Power [Member] | Other Postretirement Benefits [Member] | Pre-65 [Member]
Weighted average medical care cost trend rates used in measuring the APBO
Initial Cost Trend Rate	8.00%
Ultimate Cost Trend Rate	5.00%
Year That Ultimate Rate Is Reached	2020
Mississippi Power [Member] | Other Postretirement Benefits [Member] | Post-65 medical [Member]
Weighted average medical care cost trend rates used in measuring the APBO
Initial Cost Trend Rate	6.00%
Ultimate Cost Trend Rate	5.00%
Year That Ultimate Rate Is Reached	2020
Mississippi Power [Member] | Other Postretirement Benefits [Member] | Post-65 prescription [Member]
Weighted average medical care cost trend rates used in measuring the APBO
Initial Cost Trend Rate	6.00%
Ultimate Cost Trend Rate	5.00%
Year That Ultimate Rate Is Reached	2020
Georgia Power [Member] | Pre-65 [Member]
Weighted average medical care cost trend rates used in measuring the APBO
Initial Cost Trend Rate	8.00%
Ultimate Cost Trend Rate	5.00%
Year That Ultimate Rate Is Reached	2020
Georgia Power [Member] | Post-65 medical [Member]
Weighted average medical care cost trend rates used in measuring the APBO
Initial Cost Trend Rate	6.00%
Ultimate Cost Trend Rate	5.00%
Year That Ultimate Rate Is Reached	2020
Georgia Power [Member] | Post-65 prescription [Member]
Weighted average medical care cost trend rates used in measuring the APBO
Initial Cost Trend Rate	6.00%
Ultimate Cost Trend Rate	5.00%
Year That Ultimate Rate Is Reached	2020
Alabama Power [Member] | Other Postretirement Benefits [Member] | Pre-65 [Member]
Weighted average medical care cost trend rates used in measuring the APBO
Initial Cost Trend Rate	8.00%
Ultimate Cost Trend Rate	5.00%
Year That Ultimate Rate Is Reached	2020
Alabama Power [Member] | Other Postretirement Benefits [Member] | Post-65 medical [Member]
Weighted average medical care cost trend rates used in measuring the APBO
Initial Cost Trend Rate	6.00%
Ultimate Cost Trend Rate	5.00%
Year That Ultimate Rate Is Reached	2020
Alabama Power [Member] | Other Postretirement Benefits [Member] | Post-65 prescription [Member]
Weighted average medical care cost trend rates used in measuring the APBO
Initial Cost Trend Rate	6.00%
Ultimate Cost Trend Rate	5.00%
Year That Ultimate Rate Is Reached	2020