Effective Tax Rate and Unrecognized Tax Benefits (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012
Changes for unrecognized tax benefits
Unrecognized tax benefits as of December 31, 2011	$ 120
Tax positions from current periods	4
Tax positions from prior periods	(23)
Reductions due to settlements	(5)
Reductions due to expired statute of limitations	(3)
Unrecognized tax benefits as of June 30, 2012	93
Alabama Power [Member]
Changes for unrecognized tax benefits
Unrecognized tax benefits as of December 31, 2011	32
Tax positions from current periods	2
Tax positions from prior periods	(3)
Reductions due to settlements	(2)
Unrecognized tax benefits as of June 30, 2012	29
Georgia Power [Member]
Changes for unrecognized tax benefits
Unrecognized tax benefits as of December 31, 2011	47
Tax positions from current periods	2
Tax positions from prior periods	(19)
Reductions due to settlements	(4)
Reductions due to expired statute of limitations	(3)
Unrecognized tax benefits as of June 30, 2012	23
Gulf Power [Member]
Changes for unrecognized tax benefits
Unrecognized tax benefits as of December 31, 2011	3
Tax positions from current periods	1
Tax positions from prior periods	(1)
Reductions due to settlements	(1)
Unrecognized tax benefits as of June 30, 2012	2
Mississippi Power [Member]
Changes for unrecognized tax benefits
Unrecognized tax benefits as of December 31, 2011	5
Tax positions from prior periods	(1)
Unrecognized tax benefits as of June 30, 2012	4
Southern Power [Member]
Changes for unrecognized tax benefits
Unrecognized tax benefits as of December 31, 2011	3
Tax positions from prior periods	(2)
Reductions due to settlements	1
Unrecognized tax benefits as of June 30, 2012	$ 2