Derivatives - Financial Statement Presentation (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	$ 27,000	$ 36,000
Liability Derivatives	56,000	111,000
Hedging Instruments for Regulatory Purposes [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	23,000	23,000
Liability Derivatives	55,000	109,000
Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	16,000	10,000
Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	7,000	13,000
Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	26,000	74,000
Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	29,000	35,000
Designated as hedging instruments in cash flow and fair value hedges [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	3,000	10,000
Liability Derivatives	0	0
Designated as hedging instruments in cash flow and fair value hedges [Member] | Interest rate derivatives [Member] | Other current assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	3,000	7,000
Designated as hedging instruments in cash flow and fair value hedges [Member] | Interest rate derivatives [Member] | Other deferred charges and assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	0	3,000
Designated as hedging instruments in cash flow and fair value hedges [Member] | Interest rate derivatives [Member] | Liabilities from risk management activities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	0	0
Designated as hedging instruments in cash flow and fair value hedges [Member] | Interest rate derivatives [Member] | Other deferred credits and liabilities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	0	0
Not designated as hedging instruments [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	1,000	3,000
Liability Derivatives	1,000	2,000
Not designated as hedging instruments [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	0	1,000
Not designated as hedging instruments [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	1,000	2,000
Not designated as hedging instruments [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	1,000	1,000
Not designated as hedging instruments [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	0	1,000
Alabama Power [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	7,000	5,000
Liability Derivatives	8,000	18,000
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	7,000	5,000
Liability Derivatives	8,000	18,000
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	5,000	2,000
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	2,000	3,000
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	3,000	14,000
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	5,000	4,000
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	5,000	11,000
Liability Derivatives	21,000	45,000
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	3,000	6,000
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	2,000	5,000
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	13,000	30,000
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	8,000	15,000
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	6,962	4,358
Liability Derivatives	17,043	27,112
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	4,893	1,293
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	2,069	3,065
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	6,470	16,529
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	10,573	10,583
Mississippi Power [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	4,803	2,519
Liability Derivatives	10,282	19,483
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	4,803	2,519
Liability Derivatives	10,281	19,446
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	3,352	638
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	1,451	1,881
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	3,652	13,116
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	6,629	6,330
Mississippi Power [Member] | Designated as hedging instruments in cash flow and fair value hedges [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	0	0
Liability Derivatives	1	37
Mississippi Power [Member] | Designated as hedging instruments in cash flow and fair value hedges [Member] | Foreign currency derivatives [Member] | Other current assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	0	0
Mississippi Power [Member] | Designated as hedging instruments in cash flow and fair value hedges [Member] | Foreign currency derivatives [Member] | Other deferred charges and assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	0	0
Mississippi Power [Member] | Designated as hedging instruments in cash flow and fair value hedges [Member] | Foreign currency derivatives [Member] | Liabilities from risk management activities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	1	0
Mississippi Power [Member] | Designated as hedging instruments in cash flow and fair value hedges [Member] | Foreign currency derivatives [Member] | Other deferred credits and liabilities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	0	37
Southern Power [Member] | Energy Related Derivative [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	600	2,100
Liability Derivatives	600	1,300
Southern Power [Member] | Not designated as hedging instruments [Member] | Energy Related Derivative [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	600	2,100
Liability Derivatives	600	1,300
Southern Power [Member] | Not designated as hedging instruments [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	400	1,700
Southern Power [Member] | Not designated as hedging instruments [Member] | Energy Related Derivative [Member] | Assets from risk management activities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives	200	400
Southern Power [Member] | Not designated as hedging instruments [Member] | Energy Related Derivative [Member] | Other Current Liabilities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	600	700
Southern Power [Member] | Not designated as hedging instruments [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives	$ 0	$ 600