Effective Tax Rate and Unrecognized Tax Benefits (Details 1) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011
Impact on effective tax rate
Tax positions impacting the effective tax rate	$ 38	$ 69
Tax positions not impacting the effective tax rate	55	51
Balance of unrecognized tax benefits	93	120
Accrued interest for unrecognized tax benefits
Interest accrued as of December 31, 2011	10
Interest reclassified due to settlements	(9)
Interest accrued during the period
Balance as of June 30, 2012	1
Georgia Power [Member]
Impact on effective tax rate
Tax positions impacting the effective tax rate	3
Tax positions not impacting the effective tax rate	20
Balance of unrecognized tax benefits	23	47
Accrued interest for unrecognized tax benefits
Interest accrued as of December 31, 2011	6
Interest reclassified due to settlements	(6)
Interest accrued during the period
Other Registrants [Member]
Impact on effective tax rate
Tax positions impacting the effective tax rate	4
Tax positions not impacting the effective tax rate	33
Balance of unrecognized tax benefits	37
Accrued interest for unrecognized tax benefits
Interest accrued as of December 31, 2011	3
Interest reclassified due to settlements	(2)
Interest accrued during the period
Balance as of June 30, 2012	$ 1