Derivatives - Balance Sheet Presentation (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 43	$ 27
Derivative Liability, Fair Value, Gross Liability	43	56
Hedging Instruments for Regulatory Purposes [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	40	23
Derivative Liability, Fair Value, Gross Liability		55
Energy Related Derivative [Member] | Hedging Instruments for Regulatory Purposes [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	17	26
Energy Related Derivative [Member] | Hedging Instruments for Regulatory Purposes [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	26	29
Energy Related Derivative [Member] | Hedging Instruments for Regulatory Purposes [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	36	16
Energy Related Derivative [Member] | Hedging Instruments for Regulatory Purposes [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	4	7
Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		1
Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		1
Interest Rate Contract [Member] | Cash Flow and Fair Value Hedging [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	3	3
Alabama Power [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	12	7
Derivative Liability, Fair Value, Gross Liability	6	8
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	12	7
Derivative Liability, Fair Value, Gross Liability		8
Alabama Power [Member] | Energy Related Derivative [Member] | Hedging Instruments for Regulatory Purposes [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	1	3
Alabama Power [Member] | Energy Related Derivative [Member] | Hedging Instruments for Regulatory Purposes [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	5	5
Alabama Power [Member] | Energy Related Derivative [Member] | Hedging Instruments for Regulatory Purposes [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	11	5
Alabama Power [Member] | Energy Related Derivative [Member] | Hedging Instruments for Regulatory Purposes [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	1	2
Alabama Power [Member] | Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		0
Alabama Power [Member] | Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		0
Alabama Power [Member] | Interest Rate Contract [Member] | Cash Flow and Fair Value Hedging [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Georgia Power [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	8	5
Derivative Liability, Fair Value, Gross Liability	16	21
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	8	5
Derivative Liability, Fair Value, Gross Liability		21
Georgia Power [Member] | Energy Related Derivative [Member] | Hedging Instruments for Regulatory Purposes [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	10	13
Georgia Power [Member] | Energy Related Derivative [Member] | Hedging Instruments for Regulatory Purposes [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	6	8
Georgia Power [Member] | Energy Related Derivative [Member] | Hedging Instruments for Regulatory Purposes [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	8	3
Georgia Power [Member] | Energy Related Derivative [Member] | Hedging Instruments for Regulatory Purposes [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	2
Georgia Power [Member] | Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		0
Georgia Power [Member] | Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		0
Georgia Power [Member] | Interest Rate Contract [Member] | Cash Flow and Fair Value Hedging [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Gulf Power [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	12	7
Derivative Liability, Fair Value, Gross Liability	13	17
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	12	7
Derivative Liability, Fair Value, Gross Liability		17
Gulf Power [Member] | Energy Related Derivative [Member] | Hedging Instruments for Regulatory Purposes [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	4	6
Gulf Power [Member] | Energy Related Derivative [Member] | Hedging Instruments for Regulatory Purposes [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	9	11
Gulf Power [Member] | Energy Related Derivative [Member] | Hedging Instruments for Regulatory Purposes [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	10	5
Gulf Power [Member] | Energy Related Derivative [Member] | Hedging Instruments for Regulatory Purposes [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	2	2
Gulf Power [Member] | Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		0
Gulf Power [Member] | Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		0
Gulf Power [Member] | Interest Rate Contract [Member] | Cash Flow and Fair Value Hedging [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Mississippi Power [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	8	5
Derivative Liability, Fair Value, Gross Liability	8	10
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	8	5
Derivative Liability, Fair Value, Gross Liability		10
Mississippi Power [Member] | Energy Related Derivative [Member] | Hedging Instruments for Regulatory Purposes [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	2	4
Mississippi Power [Member] | Energy Related Derivative [Member] | Hedging Instruments for Regulatory Purposes [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	6	6
Mississippi Power [Member] | Energy Related Derivative [Member] | Hedging Instruments for Regulatory Purposes [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	7	3
Mississippi Power [Member] | Energy Related Derivative [Member] | Hedging Instruments for Regulatory Purposes [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	1	2
Mississippi Power [Member] | Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		0
Mississippi Power [Member] | Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		0
Mississippi Power [Member] | Interest Rate Contract [Member] | Cash Flow and Fair Value Hedging [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Southern Power [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	1
Derivative Liability, Fair Value, Gross Liability		1
Southern Power [Member] | Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		1
Southern Power [Member] | Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		1
Southern Power [Member] | Interest Rate Contract [Member] | Cash Flow and Fair Value Hedging [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 0	$ 0