Income Taxes - Impact of Unrecognized Tax Benefits on Effective Tax Rate, If Recognized (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Impact on effective tax rate
Tax positions impacting the effective tax rate	$ 7,000	$ 5,000	$ 69,000
Tax positions not impacting the effective tax rate	0	65,000	51,000
Balance of unrecognized tax benefits	7,000	70,000	120,000	296,000
Alabama Power [Member]
Impact on effective tax rate
Tax positions impacting the effective tax rate	0	0	5,000
Tax positions not impacting the effective tax rate	0	31,000	27,000
Balance of unrecognized tax benefits	0	31,000	32,000	43,000
Georgia Power [Member]
Impact on effective tax rate
Tax positions impacting the effective tax rate	0	0	28,000
Tax positions not impacting the effective tax rate	0	23,000	19,000
Balance of unrecognized tax benefits	0	23,000	47,000	237,000
Gulf Power [Member]
Impact on effective tax rate
Tax positions impacting the effective tax rate	45	45	1,804
Tax positions not impacting the effective tax rate	0	4,962	1,088
Balance of unrecognized tax benefits	45	5,007	2,892	3,870
Mississippi Power [Member]
Impact on effective tax rate
Tax positions impacting the effective tax rate	3,840	3,656	4,144
Tax positions not impacting the effective tax rate	0	2,099	820
Balance of unrecognized tax benefits	3,840	5,755	4,964	4,288
Southern Power [Member]
Impact on effective tax rate
Tax positions impacting the effective tax rate	1,500	300	500
Tax positions not impacting the effective tax rate	0	2,600	2,100
Balance of unrecognized tax benefits	$ 1,500	$ 2,900	$ 2,600	$ 2,300