Derivatives - Balance Sheet Presentation (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Southern Company [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 13		$ 27
Derivative Liability, Fair Value, Gross Liability	56		56
Southern Company [Member] | Hedging Instruments for Regulatory Purposes [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	11		23
Derivative Liability, Fair Value, Gross Liability	52		55
Southern Company [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	27	[1]	26	[1]
Southern Company [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	25		29
Southern Company [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	9		16
Southern Company [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		7
Southern Company [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 Company [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 Company [Member] | Interest Rate Contract [Member] | Cash Flow and Fair Value Hedging [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	4
Southern Company [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	2		3
Alabama Power [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	5		7
Derivative Liability, Fair Value, Gross Liability	12		8
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	5		7
Derivative Liability, Fair Value, Gross Liability	11		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	5	[1]	3	[1]
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	6		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	4		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 deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	1
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	1		5
Derivative Liability, Fair Value, Gross Liability	12		21
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	1		5
Derivative Liability, Fair Value, Gross Liability	12		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	[1]	13	[1]
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	2		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	1		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 deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	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	3		7
Derivative Liability, Fair Value, Gross Liability	19		17
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	3		7
Derivative Liability, Fair Value, Gross Liability	19		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	7	[1]	6	[1]
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	12		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	2		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	1		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 deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	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	2		5
Derivative Liability, Fair Value, Gross Liability	10		10
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	2		5
Derivative Liability, Fair Value, Gross Liability	10		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	5	[1]	4	[1]
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	5		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	2		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	0		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 deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	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	0		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 deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	0
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

[1] Georgia Power includes liabilities from risk management activities in other current liabilities.