Derivatives (Details 3) (USD $)	12 Months Ended			12 Months Ended
	Dec. 31, 2011 MMBTU	Dec. 31, 2011 Alabama Power [Member]	Oct. 20, 2011 Mississippi Power [Member]	Dec. 31, 2011 Southern Power [Member]	Dec. 31, 2010 Southern Power [Member]	Dec. 31, 2009 Southern Power [Member]	Dec. 31, 2011 Series 2012A 4.10% Senior Note [Member] Alabama Power [Member]
Derivatives (Textual) [Abstract]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints	9,000,000
Realized gains on termination of interest rate derivative	$ 5,000,000			$ (8,000,000)	$ (1,492,000)	$ (5,204,000)
Pre tax losses from interest expense	15,000,000
Interest rate hedge settlement							100,000,000
Series 2012A Senior Note			7.13%				4.10%
Loss on interest rate hedges		1,000,000
Period of amortized loss to interest expense		10 years
Pre-tax gains from interest rate derivatives designated as fair value hedging instruments	3,000,000
Pre-tax losses from foreign currency derivatives designated as fair value hedging instruments including pre-tax losses associated with de-designated hedges prior to de-designation	4,000,000
Fair value of derivative liabilities with contingent features	36,000,000
Maximum potential collateral requirements arising the from credit-risk-related contingent features	$ 36,000,000