Consolidated Statements of Comprehensive Income (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Changes in fair value of qualifying hedges, tax	$ (6,000,000)	$ 0	$ (7,000,000)
Reclassification adjustment for amounts of qualifying hedges included in net income, tax	3,000,000	5,000,000	7,000,000
Change in fair value of marketable securities, tax	0	(2,000,000)	0
Benefit plan net gain (loss), tax	(32,000,000)	22,000,000	(2,000,000)
Reclassification adjustment for amounts of pension and other post retirement benefit plans included in net income, tax	2,000,000	4,000,000	(4,000,000)
Alabama Power [Member]
Changes in fair value of qualifying hedges, tax	(3,000,000)	0	(7,000,000)
Reclassification adjustment for amounts of qualifying hedges included in net income, tax	1,000,000	1,000,000	1,000,000
Georgia Power [Member]
Changes in fair value of qualifying hedges, tax	(3,000,000)	0	0
Reclassification adjustment for amounts of qualifying hedges included in net income, tax	1,000,000	1,000,000	1,000,000
Gulf Power [Member]
Reclassification adjustment for amounts of qualifying hedges included in net income, tax	234,000	297,000	360,000
Mississippi Power [Member]
Changes in fair value of qualifying hedges, tax	0	0	(296,000)
Reclassification adjustment for amounts of qualifying hedges included in net income, tax	526,000	526,000	411,000
Southern Power [Member]
Changes in fair value of qualifying hedges, tax	0	0	(90,000)
Reclassification adjustment for amounts of qualifying hedges included in net income, tax	$ 169,000	$ 2,357,000	$ 3,919,000