Derivatives - Narrative (Details) (USD $) In Millions, unless otherwise specified		9 Months Ended					9 Months Ended
	Sep. 30, 2014	Sep. 30, 2014 Southern Company [Member] MMBTU	Sep. 30, 2014 Alabama Power [Member] MMBTU	Sep. 30, 2014 Georgia Power [Member] MMBTU	Sep. 30, 2014 Gulf Power [Member]	Sep. 30, 2014 Mississippi Power [Member]	Sep. 30, 2014 Southern Power [Member] MMBTU	Nov. 06, 2014 Subsequent Event [Member] Alabama Power [Member]	Nov. 06, 2014 Subsequent Event [Member] Georgia Power [Member]
Derivatives (Textual) [Abstract]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints		7,000,000	1,000,000	4,000,000			1,000,000
Derivative, Notional Amount	$ 350	$ 250						$ 100	$ 900
Maximum Potential Collateral Requirements Arising from Credit Risk Related Contingent Features	$ 26		$ 26	$ 26	$ 26	$ 26	$ 26