Financing (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012
Credit arrangements by company
Expires, 2012	$ 327
Expires, 2013	120
Expires, 2014 and Beyond	4,730
Total	5,177
Unused	5,172
Executable Term-Loans, One Year	176
Executable Term-Loans, Two Years	41
Due Within One Year, Term Out	217
Due Within One Year, No Term Out	171
Southern Company [Member]
Credit arrangements by company
Expires, 2014 and Beyond	1,000
Total	1,000
Unused	1,000
Alabama Power [Member]
Credit arrangements by company
Expires, 2012	121
Expires, 2013	35
Expires, 2014 and Beyond	1,150
Total	1,306
Unused	1,306
Executable Term-Loans, One Year	51
Due Within One Year, Term Out	51
Due Within One Year, No Term Out	71
Georgia Power [Member]
Credit arrangements by company
Expires, 2014 and Beyond	1,750
Total	1,750
Unused	1,745
Gulf Power [Member]
Credit arrangements by company
Expires, 2012	75
Expires, 2013	35
Expires, 2014 and Beyond	165
Total	275
Unused	275
Executable Term-Loans, One Year	75
Due Within One Year, Term Out	75
Due Within One Year, No Term Out	35
Mississippi Power [Member]
Credit arrangements by company
Expires, 2012	106
Expires, 2013	25
Expires, 2014 and Beyond	165
Total	296
Unused	296
Executable Term-Loans, One Year	25
Executable Term-Loans, Two Years	41
Due Within One Year, Term Out	66
Due Within One Year, No Term Out	65
Southern Power [Member]
Credit arrangements by company
Expires, 2014 and Beyond	500
Total	500
Unused	500
Other Subsidiaries [Member]
Credit arrangements by company
Expires, 2012	25
Expires, 2013	25
Total	50
Unused	50
Executable Term-Loans, One Year	25
Due Within One Year, Term Out	$ 25