Effective Tax Rate and Unrecognized Tax Benefits (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended		12 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Changes for unrecognized tax benefits
Unrecognized tax benefits as of December 31, 2010	$ 296
Tax positions from current periods	43
Tax positions from prior periods	(108)
Reductions due to settlements	(112)
Reductions due to expired statute of limitations
Balance as of September 30, 2011	119		296
Impact on effective tax rate
Tax positions impacting the effective tax rate	76		217
Tax positions not impacting the effective tax rate	43		79
Balance of unrecognized tax benefits	119		296
Accrued interest for unrecognized tax benefits
Interest accrued as of December 31, 2010	29
Interest reclassified due to settlements	(24)
Interest accrued during the period	4
Balance as of September 30, 2011	9		29
Effective Tax Rate and Unrecognized Tax Benefits (Textual) [Abstract]
Effective tax rate	36.10%	33.10%
Significantly increase or decrease in the amount of the unrecognized tax benefits associated with a majority of Southern	Next 12 Months
Positive cash flow due to tax accounting method for repair costs			297
Alabama Power [Member]
Changes for unrecognized tax benefits
Unrecognized tax benefits as of December 31, 2010	43
Tax positions from current periods	2
Tax positions from prior periods	(18)
Reductions due to expired statute of limitations
Balance as of September 30, 2011	27		43
Impact on effective tax rate
Balance of unrecognized tax benefits	27		43
Effective Tax Rate and Unrecognized Tax Benefits (Textual) [Abstract]
Effective tax rate	39.00%	36.90%
Positive cash flow due to tax accounting method for repair costs			141
Georgia Power [Member]
Changes for unrecognized tax benefits
Unrecognized tax benefits as of December 31, 2010	237
Tax positions from current periods	7
Tax positions from prior periods	(87)
Reductions due to settlements	(112)
Reductions due to expired statute of limitations
Balance as of September 30, 2011	45		237
Impact on effective tax rate
Tax positions impacting the effective tax rate	28
Tax positions not impacting the effective tax rate	17
Balance of unrecognized tax benefits	45		237
Accrued interest for unrecognized tax benefits
Interest accrued as of December 31, 2010	27
Interest reclassified due to settlements	(24)
Interest accrued during the period	2
Balance as of September 30, 2011	5		27
Effective Tax Rate and Unrecognized Tax Benefits (Textual) [Abstract]
Effective tax rate	35.80%	32.30%
Positive cash flow due to tax accounting method for repair costs			133
Gulf Power [Member]
Changes for unrecognized tax benefits
Unrecognized tax benefits as of December 31, 2010	4
Tax positions from current periods	1
Tax positions from prior periods	(2)
Reductions due to expired statute of limitations
Balance as of September 30, 2011	3		4
Impact on effective tax rate
Balance of unrecognized tax benefits	3		4
Effective Tax Rate and Unrecognized Tax Benefits (Textual) [Abstract]
Effective tax rate	36.60%	36.40%
Positive cash flow due to tax accounting method for repair costs			8
Mississippi Power [Member]
Changes for unrecognized tax benefits
Unrecognized tax benefits as of December 31, 2010	4
Tax positions from current periods	1
Tax positions from prior periods	(1)
Reductions due to expired statute of limitations
Balance as of September 30, 2011	4		4
Impact on effective tax rate
Balance of unrecognized tax benefits	4		4
Effective Tax Rate and Unrecognized Tax Benefits (Textual) [Abstract]
Effective tax rate	32.60%	36.50%
Positive cash flow due to tax accounting method for repair costs			5
Other Registrants [Member]
Changes for unrecognized tax benefits
Balance as of September 30, 2011	37
Impact on effective tax rate
Tax positions impacting the effective tax rate	12
Tax positions not impacting the effective tax rate	25
Balance of unrecognized tax benefits	37
Accrued interest for unrecognized tax benefits
Interest accrued as of December 31, 2010	2
Interest accrued during the period	1
Balance as of September 30, 2011	3
Southern Power [Member]
Changes for unrecognized tax benefits
Unrecognized tax benefits as of December 31, 2010	2
Tax positions from current periods	1
Reductions due to expired statute of limitations
Balance as of September 30, 2011	3		2
Impact on effective tax rate
Balance of unrecognized tax benefits	3		2
Effective Tax Rate and Unrecognized Tax Benefits (Textual) [Abstract]
Effective tax rate	35.90%	30.10%
Positive cash flow due to tax accounting method for repair costs			$ 6