Financing - Committed Credit Arrangements With Banks (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Credit arrangements by company
Line of Credit Expire Year One	$ 423	[1]
Line of Credit Expire Year Two	960	[1]
Line of Credit Expire Year Four	3,800	[1]
Total	5,183
Unused	5,173
Due Within One Year, Term Out	191
Due Within One Year, No Term Out	232
Executable Term-Loans, One Year	151
Executable Term-Loans, Two Years	40
Southern Company [Member]
Credit arrangements by company
Line of Credit Expire Year One	0	[1]
Line of Credit Expire Year Two	0	[1]
Line of Credit Expire Year Four	1,000	[1]
Total	1,000
Unused	1,000
Due Within One Year, Term Out	0
Due Within One Year, No Term Out	0
Executable Term-Loans, One Year	0
Executable Term-Loans, Two Years	0
Alabama Power [Member]
Credit arrangements by company
Line of Credit Expire Year One	158	[1]
Line of Credit Expire Year Two	350	[1]
Line of Credit Expire Year Four	800	[1]
Total	1,308
Unused	1,308
Due Within One Year, Term Out	56
Due Within One Year, No Term Out	102
Executable Term-Loans, One Year	56
Executable Term-Loans, Two Years	0
Georgia Power [Member]
Credit arrangements by company
Line of Credit Expire Year One	0	[1]
Line of Credit Expire Year Two	250	[1],[2]
Line of Credit Expire Year Four	1,500	[1],[2]
Total	1,750
Unused	1,740
Due Within One Year, Term Out	0
Due Within One Year, No Term Out	0
Executable Term-Loans, One Year	0
Executable Term-Loans, Two Years	0
Gulf Power [Member]
Credit arrangements by company
Line of Credit Expire Year One	80	[1]
Line of Credit Expire Year Two	195	[1]
Line of Credit Expire Year Four	0	[1]
Total	275	[3]
Unused	275
Due Within One Year, Term Out	45
Due Within One Year, No Term Out	35
Executable Term-Loans, One Year	45
Executable Term-Loans, Two Years	0
Mississippi Power [Member]
Credit arrangements by company
Line of Credit Expire Year One	135	[1],[3]
Line of Credit Expire Year Two	165	[1],[3]
Line of Credit Expire Year Four	0	[1]
Total	300	[3]
Unused	300
Due Within One Year, Term Out	65
Due Within One Year, No Term Out	70
Executable Term-Loans, One Year	25
Executable Term-Loans, Two Years	40
Southern Power [Member]
Credit arrangements by company
Line of Credit Expire Year One	0	[1]
Line of Credit Expire Year Two	0	[1]
Line of Credit Expire Year Four	500	[1]
Total	500
Unused	500
Due Within One Year, Term Out	0
Due Within One Year, No Term Out	0
Executable Term-Loans, One Year	0
Executable Term-Loans, Two Years	0
Other Subsidiaries [Member]
Credit arrangements by company
Line of Credit Expire Year One	50	[1]
Line of Credit Expire Year Two	0	[1]
Line of Credit Expire Year Four	0	[1]
Total	50
Unused	50
Due Within One Year, Term Out	25
Due Within One Year, No Term Out	25
Executable Term-Loans, One Year	25
Executable Term-Loans, Two Years	$ 0

[1] No credit arrangements expire in 2015.

[2] (a)No credit arrangements expire in 2013 or 2015.

[3] No credit arrangements expire after 2014.