Effective Tax Rate and Unrecognized Tax Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012
Changes for unrecognized tax benefits
Unrecognized tax benefits as of December 31, 2011	$ 120
Tax positions from current periods	3
Tax positions from prior periods	(6)
Reductions due to settlements	(5)
Reductions due to expired statute of limitations
Unrecognized tax benefits as of March 31, 2012	112
Alabama Power [Member]
Changes for unrecognized tax benefits
Unrecognized tax benefits as of December 31, 2011	32
Tax positions from current periods	1
Tax positions from prior periods	(3)
Reductions due to settlements	(2)
Reductions due to expired statute of limitations
Unrecognized tax benefits as of March 31, 2012	28
Georgia Power [Member]
Changes for unrecognized tax benefits
Unrecognized tax benefits as of December 31, 2011	47
Tax positions from current periods	1
Tax positions from prior periods	(1)
Reductions due to settlements	(3)
Reductions due to expired statute of limitations
Unrecognized tax benefits as of March 31, 2012	44
Gulf Power [Member]
Changes for unrecognized tax benefits
Unrecognized tax benefits as of December 31, 2011	3
Reductions due to settlements	(1)
Reductions due to expired statute of limitations
Unrecognized tax benefits as of March 31, 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)
Reductions due to expired statute of limitations
Unrecognized tax benefits as of March 31, 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
Reductions due to expired statute of limitations
Unrecognized tax benefits as of March 31, 2012	$ 2