Derivatives (Details Textual) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2012 MMBTU
Derivative [Line Items]
Gain (Loss) on Foreign Currency Fair Value Hedge Derivatives	$ (3)	$ (2)
Derivatives (Textual) [Abstract]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints		7,000,000
Maximum potential collateral requirements arising the from credit-risk-related contingent features	10	10
Alabama Power [Member]
Derivatives (Textual) [Abstract]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints		1,000,000
Maximum potential collateral requirements arising the from credit-risk-related contingent features	10	10
Georgia Power [Member]
Derivatives (Textual) [Abstract]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints		3,000,000
Maximum potential collateral requirements arising the from credit-risk-related contingent features	10	10
Gulf Power [Member]
Derivatives (Textual) [Abstract]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints		1,000,000
Maximum potential collateral requirements arising the from credit-risk-related contingent features	10	10
Mississippi Power [Member]
Derivative [Line Items]
Gain (Loss) on Foreign Currency Fair Value Hedge Derivatives	(3)	(2)
Derivatives (Textual) [Abstract]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints		1,000,000
Maximum potential collateral requirements arising the from credit-risk-related contingent features	10	10
Southern Power [Member]
Derivatives (Textual) [Abstract]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints		1,000,000
Maximum potential collateral requirements arising the from credit-risk-related contingent features	$ 10	$ 10