Effective Tax Rate and Unrecognized Tax Benefits (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
Changes for Unrecognized Tax Benefits [Roll Forward]
Unrecognized tax benefits as of December 31, 2011	$ 120
Tax positions from current periods	7
Tax positions from prior periods	(21)
Reductions due to settlements	(5)
Reductions due to expired statute of limitations	(3)
Unrecognized tax benefits as of September 30, 2012	98
Alabama Power [Member]
Changes for Unrecognized Tax Benefits [Roll Forward]
Unrecognized tax benefits as of December 31, 2011	32
Tax positions from current periods	3
Tax positions from prior periods	(4)
Reductions due to settlements	(2)
Reductions due to expired statute of limitations	0
Unrecognized tax benefits as of September 30, 2012	29
Georgia Power [Member]
Changes for Unrecognized Tax Benefits [Roll Forward]
Unrecognized tax benefits as of December 31, 2011	47
Tax positions from current periods	2
Tax positions from prior periods	(18)
Reductions due to settlements	(3)
Reductions due to expired statute of limitations	(3)
Unrecognized tax benefits as of September 30, 2012	25
Gulf Power [Member]
Changes for Unrecognized Tax Benefits [Roll Forward]
Unrecognized tax benefits as of December 31, 2011	3
Tax positions from current periods	0
Tax positions from prior periods	1
Reductions due to settlements	(1)
Reductions due to expired statute of limitations	0
Unrecognized tax benefits as of September 30, 2012	3
Mississippi Power [Member]
Changes for Unrecognized Tax Benefits [Roll Forward]
Unrecognized tax benefits as of December 31, 2011	5
Tax positions from current periods	0
Tax positions from prior periods	0
Reductions due to settlements	0
Reductions due to expired statute of limitations	0
Unrecognized tax benefits as of September 30, 2012	5
Southern Power [Member]
Changes for Unrecognized Tax Benefits [Roll Forward]
Unrecognized tax benefits as of December 31, 2011	3
Tax positions from current periods	1
Tax positions from prior periods	(2)
Reductions due to settlements	1
Reductions due to expired statute of limitations	0
Unrecognized tax benefits as of September 30, 2012	$ 3