Financing - Committed Credit Arrangements With Banks (Details) - USD ($)	Dec. 31, 2015	Aug. 31, 2015	Dec. 31, 2014	Mar. 31, 2012
Credit arrangements by company
Expires, 2015	$ 410,000,000
Expires, 2016	30,000,000
Expires, 2017	1,665,000,000
Expires, 2020	4,400,000,000
Total	6,505,000,000
Unused	6,428,000,000
Executable Term-Loans, One Year	80,000,000
Executable Term-Loans, Two Years	15,000,000
Due Within One Year, Term Out	95,000,000
Due Within One Year, No Term Out	315,000,000
Southern Company [Member]
Credit arrangements by company
Expires, 2015	0
Expires, 2016	0
Expires, 2017	1,000,000,000
Expires, 2020	1,250,000,000
Total	2,250,000,000	$ 1,250,000,000	$ 1,000,000,000
Unused	2,250,000,000
Executable Term-Loans, One Year	0
Executable Term-Loans, Two Years	0
Due Within One Year, Term Out	0
Due Within One Year, No Term Out	0
Alabama Power [Member]
Credit arrangements by company
Expires, 2015	40,000,000
Expires, 2016	0
Expires, 2017	500,000,000
Expires, 2020	800,000,000
Total	1,340,000,000
Unused	1,340,000,000
Executable Term-Loans, One Year	0
Executable Term-Loans, Two Years	0
Due Within One Year, Term Out	0
Due Within One Year, No Term Out	40,000,000
Georgia Power [Member]
Credit arrangements by company
Expires, 2015	0
Expires, 2016	0
Expires, 2017	0
Expires, 2020	1,750,000,000
Total	1,750,000,000
Unused	1,732,000,000
Executable Term-Loans, One Year	0
Executable Term-Loans, Two Years	0
Due Within One Year, Term Out	0
Due Within One Year, No Term Out	0
Gulf Power [Member]
Credit arrangements by company
Expires, 2015	80,000,000
Expires, 2016	30,000,000
Expires, 2017	165,000,000
Expires, 2020	0
Total	275,000,000
Unused	275,000,000
Executable Term-Loans, One Year	50,000,000
Executable Term-Loans, Two Years	0
Due Within One Year, Term Out	50,000,000
Due Within One Year, No Term Out	30,000,000
Mississippi Power [Member]
Line of Credit Facility [Line Items]
Deposit Liability, Current				$ 150,000,000
Credit arrangements by company
Expires, 2015	220,000,000
Expires, 2016	0
Expires, 2017	0
Expires, 2020	0
Total	220,000,000
Unused	195,000,000
Executable Term-Loans, One Year	30,000,000
Executable Term-Loans, Two Years	15,000,000
Due Within One Year, Term Out	45,000,000
Due Within One Year, No Term Out	175,000,000
Southern Power [Member]
Credit arrangements by company
Expires, 2015	0
Expires, 2016	0
Expires, 2017	0
Expires, 2020	600,000,000
Total	600,000,000	$ 600,000,000	500,000,000
Unused	566,000,000		$ 488,000,000
Executable Term-Loans, One Year	0
Executable Term-Loans, Two Years	0
Due Within One Year, Term Out	0
Due Within One Year, No Term Out	0
Other Subsidiaries [Member]
Credit arrangements by company
Expires, 2015	70,000,000
Expires, 2016	0
Expires, 2017	0
Expires, 2020	0
Total	70,000,000
Unused	70,000,000
Executable Term-Loans, One Year	0
Executable Term-Loans, Two Years	0
Due Within One Year, Term Out	0
Due Within One Year, No Term Out	70,000,000
Scenario, Plan [Member] | Bridge Agreement [Member]
Credit arrangements by company
Total	$ 8,100,000,000.0