Fair Value Measurements (Details 1) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012
Corporate bonds - commingled funds [Member]
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments
Fair Value	$ 12
Unfunded Commitments	0
Redemption Frequency	Daily
Redemption Notice Period	1 to 3 days
Corporate bonds - commingled funds [Member] | Georgia Power [Member]
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments
Fair Value	12
Unfunded Commitments	0
Redemption Frequency	Daily
Redemption Notice Period	1 to 3 days
Other - commingled funds [Member]
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments
Fair Value	87
Unfunded Commitments	0
Redemption Frequency	Daily/Monthly
Redemption Notice Period	Daily/7days
Other - commingled funds [Member] | Alabama Power [Member]
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments
Fair Value	56
Unfunded Commitments	0
Redemption Frequency	Daily/Monthly
Redemption Notice Period	Daily/7days
Other - commingled funds [Member] | Georgia Power [Member]
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments
Fair Value	31
Unfunded Commitments	0
Redemption Frequency	Daily
Redemption Notice Period	Not applicable
Trust owned life insurance [Member]
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments
Fair Value	93
Unfunded Commitments	0
Redemption Frequency	Daily
Redemption Notice Period	15 days
Trust owned life insurance [Member] | Alabama Power [Member]
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments
Fair Value	93
Unfunded Commitments	0
Redemption Frequency	Daily
Redemption Notice Period	15 days
Money market funds [Member]
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments
Fair Value	862
Unfunded Commitments	0
Redemption Frequency	Daily
Redemption Notice Period	Not applicable
Money market funds [Member] | Alabama Power [Member]
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments
Fair Value	234
Unfunded Commitments	0
Redemption Frequency	Daily
Redemption Notice Period	Not applicable
Money market funds [Member] | Gulf Power [Member]
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments
Fair Value	15
Unfunded Commitments	0
Redemption Frequency	Daily
Redemption Notice Period	Not applicable
Money market funds [Member] | Mississippi Power [Member]
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments
Fair Value	439
Unfunded Commitments	$ 0
Redemption Frequency	Daily
Redemption Notice Period	Not applicable