Derivatives (Details 1) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	$ 39
Liability Derivatives	300
Energy-related derivatives [Member]
Pre-tax effect of unrealized derivative gains (losses)
Regulatory hedge unrealized gain (loss) recognized on balance sheet	(249)
Energy-related derivatives [Member] | Other regulatory assets, current [Member]
Pre-tax effect of unrealized derivative gains (losses)
Regulatory hedge unrealized gain (loss) recognized on balance sheet	(191)
Energy-related derivatives [Member] | Other regulatory assets, deferred [Member]
Pre-tax effect of unrealized derivative gains (losses)
Regulatory hedge unrealized gain (loss) recognized on balance sheet	(81)
Energy-related derivatives [Member] | Other regulatory liabilities, current [Member]
Pre-tax effect of unrealized derivative gains (losses)
Regulatory hedge unrealized gain (loss) recognized on balance sheet	17
Energy-related derivatives [Member] | Other regulatory liabilities, deferred [Member]
Pre-tax effect of unrealized derivative gains (losses)
Regulatory hedge unrealized gain (loss) recognized on balance sheet	6
Alabama Power [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	1
Liability Derivatives	64
Alabama Power [Member] | Energy-related derivatives [Member]
Pre-tax effect of unrealized derivative gains (losses)
Regulatory hedge unrealized gain (loss) recognized on balance sheet	(53)
Alabama Power [Member] | Energy-related derivatives [Member] | Other regulatory assets, current [Member]
Pre-tax effect of unrealized derivative gains (losses)
Regulatory hedge unrealized gain (loss) recognized on balance sheet	(41)
Alabama Power [Member] | Energy-related derivatives [Member] | Other regulatory assets, deferred [Member]
Pre-tax effect of unrealized derivative gains (losses)
Regulatory hedge unrealized gain (loss) recognized on balance sheet	(13)
Alabama Power [Member] | Energy-related derivatives [Member] | Other regulatory liabilities, deferred [Member]
Pre-tax effect of unrealized derivative gains (losses)
Regulatory hedge unrealized gain (loss) recognized on balance sheet	1
Georgia Power [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	22
Liability Derivatives	108
Georgia Power [Member] | Energy-related derivatives [Member]
Pre-tax effect of unrealized derivative gains (losses)
Regulatory hedge unrealized gain (loss) recognized on balance sheet	(86)
Georgia Power [Member] | Energy-related derivatives [Member] | Other deferred credits and liabilities [Member]
Pre-tax effect of unrealized derivative gains (losses)
Regulatory hedge unrealized gain (loss) recognized on balance sheet	5
Georgia Power [Member] | Energy-related derivatives [Member] | Other regulatory assets, current [Member]
Pre-tax effect of unrealized derivative gains (losses)
Regulatory hedge unrealized gain (loss) recognized on balance sheet	(80)
Georgia Power [Member] | Energy-related derivatives [Member] | Other regulatory assets, deferred [Member]
Pre-tax effect of unrealized derivative gains (losses)
Regulatory hedge unrealized gain (loss) recognized on balance sheet	(28)
Georgia Power [Member] | Energy-related derivatives [Member] | Other regulatory liabilities, current [Member]
Pre-tax effect of unrealized derivative gains (losses)
Regulatory hedge unrealized gain (loss) recognized on balance sheet	17
Gulf Power [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	54
Gulf Power [Member] | Energy-related derivatives [Member]
Pre-tax effect of unrealized derivative gains (losses)
Regulatory hedge unrealized gain (loss) recognized on balance sheet	(54)
Gulf Power [Member] | Energy-related derivatives [Member] | Other regulatory assets, current [Member]
Pre-tax effect of unrealized derivative gains (losses)
Regulatory hedge unrealized gain (loss) recognized on balance sheet	(31)
Gulf Power [Member] | Energy-related derivatives [Member] | Other regulatory assets, deferred [Member]
Pre-tax effect of unrealized derivative gains (losses)
Regulatory hedge unrealized gain (loss) recognized on balance sheet	(23)
Mississippi Power [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	1
Liability Derivatives	57
Mississippi Power [Member] | Energy-related derivatives [Member]
Pre-tax effect of unrealized derivative gains (losses)
Regulatory hedge unrealized gain (loss) recognized on balance sheet	(56)
Mississippi Power [Member] | Energy-related derivatives [Member] | Other regulatory assets, current [Member]
Pre-tax effect of unrealized derivative gains (losses)
Regulatory hedge unrealized gain (loss) recognized on balance sheet	(39)
Mississippi Power [Member] | Energy-related derivatives [Member] | Other regulatory assets, deferred [Member]
Pre-tax effect of unrealized derivative gains (losses)
Regulatory hedge unrealized gain (loss) recognized on balance sheet	(17)
Southern Power [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	1
Liability Derivatives	17
Cash Flow and Fair Value Hedging [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	14
Liability Derivatives	12
Cash Flow and Fair Value Hedging [Member] | Energy-related derivatives [Member] | Liabilities from risk management activities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	2
Cash Flow and Fair Value Hedging [Member] | Interest rate derivatives [Member] | Other current assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	6
Cash Flow and Fair Value Hedging [Member] | Interest rate derivatives [Member] | Other deferred charges and assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	8
Cash Flow and Fair Value Hedging [Member] | Interest rate derivatives [Member] | Liabilities from risk management activities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	10
Cash Flow and Fair Value Hedging [Member] | Alabama Power [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	10
Cash Flow and Fair Value Hedging [Member] | Alabama Power [Member] | Interest rate derivatives [Member] | Liabilities from risk management activities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	10
Cash Flow and Fair Value Hedging [Member] | Southern Power [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	2
Cash Flow and Fair Value Hedging [Member] | Southern Power [Member] | Energy-related derivatives [Member] | Liabilities from risk management activities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	2
Hedging Instruments for Regulatory Purposes [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	23
Liability Derivatives	272
Hedging Instruments for Regulatory Purposes [Member] | Energy-related derivatives [Member] | Other current assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	17
Hedging Instruments for Regulatory Purposes [Member] | Energy-related derivatives [Member] | Other deferred charges and assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	6
Hedging Instruments for Regulatory Purposes [Member] | Energy-related derivatives [Member] | Liabilities from risk management activities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	191
Hedging Instruments for Regulatory Purposes [Member] | Energy-related derivatives [Member] | Other deferred credits and liabilities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	81
Hedging Instruments for Regulatory Purposes [Member] | Alabama Power [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	1
Liability Derivatives	54
Hedging Instruments for Regulatory Purposes [Member] | Alabama Power [Member] | Energy-related derivatives [Member] | Other deferred charges and assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	1
Hedging Instruments for Regulatory Purposes [Member] | Alabama Power [Member] | Energy-related derivatives [Member] | Liabilities from risk management activities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	41
Hedging Instruments for Regulatory Purposes [Member] | Alabama Power [Member] | Energy-related derivatives [Member] | Other deferred credits and liabilities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	13
Hedging Instruments for Regulatory Purposes [Member] | Georgia Power [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	22
Liability Derivatives	108
Hedging Instruments for Regulatory Purposes [Member] | Georgia Power [Member] | Energy-related derivatives [Member] | Other current assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	17
Hedging Instruments for Regulatory Purposes [Member] | Georgia Power [Member] | Energy-related derivatives [Member] | Other deferred charges and assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	5
Hedging Instruments for Regulatory Purposes [Member] | Georgia Power [Member] | Energy-related derivatives [Member] | Liabilities from risk management activities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	80
Hedging Instruments for Regulatory Purposes [Member] | Georgia Power [Member] | Energy-related derivatives [Member] | Other deferred credits and liabilities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	28
Hedging Instruments for Regulatory Purposes [Member] | Gulf Power [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	54
Hedging Instruments for Regulatory Purposes [Member] | Gulf Power [Member] | Energy-related derivatives [Member] | Liabilities from risk management activities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	31
Hedging Instruments for Regulatory Purposes [Member] | Gulf Power [Member] | Energy-related derivatives [Member] | Other deferred credits and liabilities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	23
Hedging Instruments for Regulatory Purposes [Member] | Mississippi Power [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	56
Hedging Instruments for Regulatory Purposes [Member] | Mississippi Power [Member] | Energy-related derivatives [Member] | Liabilities from risk management activities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	39
Hedging Instruments for Regulatory Purposes [Member] | Mississippi Power [Member] | Energy-related derivatives [Member] | Other deferred credits and liabilities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	17
Not Designated as Hedging Instrument [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	2
Liability Derivatives	16
Not Designated as Hedging Instrument [Member] | Energy-related derivatives [Member] | Other deferred charges and assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	1
Not Designated as Hedging Instrument [Member] | Energy-related derivatives [Member] | Liabilities from risk management activities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	15
Not Designated as Hedging Instrument [Member] | Foreign currency derivatives [Member] | Other current assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	1
Not Designated as Hedging Instrument [Member] | Foreign currency derivatives [Member] | Liabilities from risk management activities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	1
Not Designated as Hedging Instrument [Member] | Mississippi Power [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	1
Liability Derivatives	1
Not Designated as Hedging Instrument [Member] | Mississippi Power [Member] | Foreign currency derivatives [Member] | Other current assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	1
Not Designated as Hedging Instrument [Member] | Mississippi Power [Member] | Foreign currency derivatives [Member] | Liabilities from risk management activities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	1
Not Designated as Hedging Instrument [Member] | Southern Power [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	1
Liability Derivatives	15
Not Designated as Hedging Instrument [Member] | Southern Power [Member] | Energy-related derivatives [Member] | Other deferred charges and assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	1
Not Designated as Hedging Instrument [Member] | Southern Power [Member] | Energy-related derivatives [Member] | Liabilities from risk management activities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	$ 15