Derivatives (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Interest expense, net of amounts capitalized [Member]
Pre-tax effect of derivatives designated as cash flow hedging instruments
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	$ (4)	$ (5)	$ (12)	$ (10)
Alabama Power [Member] | Interest expense, net of amounts capitalized [Member]
Pre-tax effect of derivatives designated as cash flow hedging instruments
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	0	0	0	3
Georgia Power [Member] | Interest expense, net of amounts capitalized [Member]
Pre-tax effect of derivatives designated as cash flow hedging instruments
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(1)	(1)	(3)	(3)
Gulf Power [Member] | Interest expense, net of amounts capitalized [Member]
Pre-tax effect of derivatives designated as cash flow hedging instruments
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)			(1)	(1)
Mississippi Power [Member] | Interest expense, net of amounts capitalized [Member]
Pre-tax effect of derivatives designated as cash flow hedging instruments
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	0	0	(1)	0
Southern Power [Member] | Interest expense, net of amounts capitalized [Member]
Pre-tax effect of derivatives designated as cash flow hedging instruments
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(3)	(3)	(8)	(8)
Interest rate derivatives [Member]
Pre-tax effect of derivatives designated as cash flow hedging instruments
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	(4)	(27)	(16)	(23)
Interest rate derivatives [Member] | Alabama Power [Member]
Pre-tax effect of derivatives designated as cash flow hedging instruments
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	(4)	(12)	(15)	(8)
Interest rate derivatives [Member] | Georgia Power [Member]
Pre-tax effect of derivatives designated as cash flow hedging instruments
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	0	0	0	0
Interest rate derivatives [Member] | Gulf Power [Member]
Pre-tax effect of derivatives designated as cash flow hedging instruments
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)			0	0
Interest rate derivatives [Member] | Mississippi Power [Member]
Pre-tax effect of derivatives designated as cash flow hedging instruments
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	0	(15)	(1)	(15)
Interest rate derivatives [Member] | Southern Power [Member]
Pre-tax effect of derivatives designated as cash flow hedging instruments
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	$ 0	$ 0	$ 0	$ 0