Derivatives - Balance Sheet Presentation (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	$ 1
Southern Company [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	63	$ 29
Derivatives, liabilities	155	250
Southern Company [Member] | Energy Related Derivative [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount offset against collateral	4	1
Derivative liability amount offset against collateral	78	214
Southern Company [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	36	7
Derivatives, liabilities	110	220
Southern Company [Member] | Energy Related Derivative [Member] | Gross Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount not offset against collateral	32	6
Derivative liability amount not offset against collateral	32	6
Southern Company [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount offset against collateral		13
Derivative liability amount offset against collateral		21
Southern Company [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		22
Derivatives, liabilities		30
Southern Company [Member] | Interest Rate Contract [Member] | Gross Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount not offset against collateral		9
Derivative liability amount not offset against collateral		9
Southern Company [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		4
Southern Company [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	2	1
Southern Company [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		1
Southern Company [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		3
Southern Company [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	28
Derivatives, liabilities	105	217
Southern Company [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	12	3
Southern Company [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	16
Southern Company [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	61	130
Southern Company [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	44	87
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	33	22
Derivatives, liabilities	49	32
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	5	3
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	3	2
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	1
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	11	19
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	16
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	7	23
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		7
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	24
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	14
Alabama Power [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	10	1
Derivatives, liabilities	22	70
Alabama Power [Member] | Energy Related Derivative [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount offset against collateral	2	0
Derivative liability amount offset against collateral	14	54
Alabama Power [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	10	1
Derivatives, liabilities	22	55
Alabama Power [Member] | Energy Related Derivative [Member] | Gross Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount not offset against collateral	8	1
Derivative liability amount not offset against collateral	8	1
Alabama Power [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount offset against collateral		0
Derivative liability amount offset against collateral		15
Alabama Power [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Derivatives, liabilities		15
Alabama Power [Member] | Interest Rate Contract [Member] | Gross Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount not offset against collateral		0
Derivative liability amount not offset against collateral		0
Alabama Power [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Alabama Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Alabama Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	0
Alabama Power [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	10
Derivatives, liabilities	22	55
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	5	1
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	5
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	17	40
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	5	15
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Derivatives, liabilities	0	15
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	0
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	15
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0
Georgia Power [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	29	7
Derivatives, liabilities	5	21
Georgia Power [Member] | Energy Related Derivative [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount offset against collateral	11	0
Derivative liability amount offset against collateral	1	13
Georgia Power [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	15	2
Derivatives, liabilities	5	15
Georgia Power [Member] | Energy Related Derivative [Member] | Gross Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount not offset against collateral	4	2
Derivative liability amount not offset against collateral	4	2
Georgia Power [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount offset against collateral		1
Derivative liability amount offset against collateral		2
Georgia Power [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		5
Derivatives, liabilities		6
Georgia Power [Member] | Interest Rate Contract [Member] | Gross Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount not offset against collateral		4
Derivative liability amount not offset against collateral		4
Georgia Power [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Georgia Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Georgia Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	0
Georgia Power [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	15
Derivatives, liabilities	5	15
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	6	2
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	9
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	4	12
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	1	3
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	14	5
Derivatives, liabilities	0	6
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	0
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	6	5
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	8
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	0
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		6
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0
Gulf Power [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	2	1
Derivatives, liabilities	62	100
Gulf Power [Member] | Energy Related Derivative [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount offset against collateral	0	0
Derivative liability amount offset against collateral	53	100
Gulf Power [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	2	0
Derivatives, liabilities	55	100
Gulf Power [Member] | Energy Related Derivative [Member] | Gross Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount not offset against collateral	2	0
Derivative liability amount not offset against collateral	2	0
Gulf Power [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount offset against collateral		1
Derivative liability amount offset against collateral		0
Gulf Power [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		1
Derivatives, liabilities		0
Gulf Power [Member] | Interest Rate Contract [Member] | Gross Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount not offset against collateral		0
Derivative liability amount not offset against collateral		0
Gulf Power [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Gulf Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Gulf Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	0
Gulf Power [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	2
Derivatives, liabilities	55	100
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1	0
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	25	49
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	30	51
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	1
Derivatives, liabilities	7	0
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	0
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	1
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	7	0
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0
Mississippi Power [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1	0
Derivatives, liabilities	23	47
Mississippi Power [Member] | Energy Related Derivative [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount offset against collateral	0	0
Derivative liability amount offset against collateral	22	47
Mississippi Power [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1	0
Derivatives, liabilities	23	47
Mississippi Power [Member] | Energy Related Derivative [Member] | Gross Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount not offset against collateral	1	0
Derivative liability amount not offset against collateral	1	0
Mississippi Power [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount offset against collateral		0
Derivative liability amount offset against collateral		0
Mississippi Power [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Derivatives, liabilities		0
Mississippi Power [Member] | Interest Rate Contract [Member] | Gross Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount not offset against collateral		0
Derivative liability amount not offset against collateral		0
Mississippi Power [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Mississippi Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Mississippi Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	0
Mississippi Power [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1
Derivatives, liabilities	23	47
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	15	29
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	8	18
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Derivatives, liabilities	0	0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0
Southern Power [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	8	7
Derivatives, liabilities	43	3
Southern Power [Member] | Energy Related Derivative [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount offset against collateral	5	3
Derivative liability amount offset against collateral	2	2
Southern Power [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	8	4
Derivatives, liabilities	5	3
Southern Power [Member] | Energy Related Derivative [Member] | Gross Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount not offset against collateral	3	1
Derivative liability amount not offset against collateral	3	1
Southern Power [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount offset against collateral		3
Derivative liability amount offset against collateral		0
Southern Power [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		3
Derivatives, liabilities		0
Southern Power [Member] | Interest Rate Contract [Member] | Gross Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative asset amount not offset against collateral		0
Derivative liability amount not offset against collateral		0
Southern Power [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		4
Southern Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	2	1
Southern Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	1	1
Southern Power [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		3
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	6	3
Derivatives, liabilities	42	2
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	5	3
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	3	2
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	1
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	0
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		$ 0
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	24
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	$ 14