Derivatives (Details Textual) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012 MMBTU
Derivatives (Textual) [Abstract]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints	9,000,000
Pre-tax gains from foreign currency derivatives designated as fair value hedging instruments	$ 3
Maximum potential collateral requirements arising the from credit-risk-related contingent features	36
Energy-related derivatives [Member]
Derivatives (Textual) [Abstract]
Pre-tax losses from energy-related derivatives not designated as hedging instruments on the statements of income	6
Alabama Power [Member]
Derivatives (Textual) [Abstract]
Maximum potential collateral requirements arising the from credit-risk-related contingent features	36
Georgia Power [Member]
Derivatives (Textual) [Abstract]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints	4,000,000
Maximum potential collateral requirements arising the from credit-risk-related contingent features	36
Gulf Power [Member]
Derivatives (Textual) [Abstract]
Maximum potential collateral requirements arising the from credit-risk-related contingent features	36
Mississippi Power [Member]
Derivatives (Textual) [Abstract]
Pre-tax gains from foreign currency derivatives designated as fair value hedging instruments	3
Maximum potential collateral requirements arising the from credit-risk-related contingent features	36
Southern Power [Member]
Derivatives (Textual) [Abstract]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints	2,000,000
Maximum potential collateral requirements arising the from credit-risk-related contingent features	36
Southern Power [Member] | Energy-related derivatives [Member]
Derivatives (Textual) [Abstract]
Pre-tax losses from energy-related derivatives not designated as hedging instruments on the statements of income	$ 6