Derivatives - Textual (Details) (USD $)	1 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2012 MMBTU		Dec. 31, 2011	Dec. 31, 2010	Oct. 20, 2011
Derivatives (Textual) [Abstract]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints		6,000,000
Realized gains on termination of interest rate derivative		$ 52,000,000
Realized gain on termination of interest rate derivatives		(19,000,000)		(28,000,000)	(1,000,000)
Estimated pre-tax losses that will be reclassifed from OCI to interest expense for the next 12-month period		14,000,000
Fair value of derivative liabilities with contingent features		15,000,000
Maximum potential collateral requirements arising the from credit-risk-related contingent features		15,000,000
Alabama Power [Member]
Derivatives (Textual) [Abstract]
Net volume of energy-related derivative contracts for natural gas positions		57,000,000	[1]
Longest Hedge Date		2017
Realized gains on termination of interest rate derivative		36,000,000
Estimated pre-tax losses that will be reclassifed from OCI to interest expense for the next 12-month period		3,000,000
Fair value of derivative liabilities with contingent features		2,000,000
Maximum potential collateral requirements arising the from credit-risk-related contingent features		15,000,000
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
Series 2012A Senior Note		7.90%		7.40%
Fair value of derivative liabilities with contingent features		6,000,000
Maximum potential collateral requirements arising the from credit-risk-related contingent features		15,000,000
Description of Reclassification of Interest Rate Cash Flow Hedge Gain (Loss)		2037
Gulf Power [Member]
Derivatives (Textual) [Abstract]
Net volume of energy-related derivative contracts for natural gas positions		70,510,000	[2]
Longest Hedge Date		2017
Estimated pre-tax losses that will be reclassifed from OCI to interest expense for the next 12-month period		800,000
Fair value of derivative liabilities with contingent features		4,000,000
Maximum potential collateral requirements arising the from credit-risk-related contingent features		15,000,000
Mississippi Power [Member]
Derivatives (Textual) [Abstract]
Net volume of energy-related derivative contracts for natural gas positions		38,000,000	[2]
Longest Hedge Date		2017
Realized gain on termination of interest rate derivatives		16,000,000
Interest rate hedge settlement	300,000,000
Series 2012A Senior Note		9.967%				7.13%
Estimated pre-tax losses that will be reclassifed from OCI to interest expense for the next 12-month period		1,400,000
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		600,000		3,600,000	3,300,000
Fair value of derivative liabilities with contingent features		2,900,000
Maximum potential collateral requirements arising the from credit-risk-related contingent features		15,100,000
Southern Power [Member]
Derivatives (Textual) [Abstract]
Realized gains on termination of interest rate derivative		9,275,000		(8,000,000)	(1,492,000)
Realized gain on termination of interest rate derivatives		(200,000)		100,000	1,500,000
Maximum potential collateral requirements arising the from credit-risk-related contingent features		15,100,000
Interest rate hedges [Member] | Southern Power [Member]
Derivatives (Textual) [Abstract]
Estimated pre-tax losses that will be reclassifed from OCI to interest expense for the next 12-month period		$ (6,500,000)
Public Utilities, Inventory, Natural Gas [Member]
Derivatives (Textual) [Abstract]
Net volume of energy-related derivative contracts for natural gas positions		276,000,000	[3]
Public Utilities, Inventory, Natural Gas [Member] | Georgia Power [Member]
Derivatives (Textual) [Abstract]
Net volume of energy-related derivative contracts for natural gas positions		105,000,000
Longest Hedge Date		2017
Public Utilities, Inventory, Natural Gas [Member] | Southern Power [Member]
Derivatives (Textual) [Abstract]
Net volume of energy-related derivative contracts for natural gas positions		5,000,000
Longest Non-Hedge Date		2017

[1] *mmBtu – million British thermal units

[2] *mmBtu — million British thermal units

[3] *million British thermal units