Condensed Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Changes in fair value, tax	$ (18)	$ 23	$ (3)	$ 17
Reclassification adjustment for cash flow hedge, gain (loss), tax	21	(25)	15	(26)
Reclassification adjustment for pension and other post retirement benefit plans, tax	1	1	1	1
ALABAMA POWER CO
Reclassification adjustment for cash flow hedge, gain (loss), tax	0	1	1	1
GEORGIA POWER CO
Reclassification adjustment for cash flow hedge, gain (loss), tax	0	0	1	1
GULF POWER CO
Changes in fair value, tax	0	0	0	(1)
MISSISSIPPI POWER CO
Changes in fair value, tax	0	0	(1)	0
Reclassification adjustment for cash flow hedge, gain (loss), tax	0	0	0	0
SOUTHERN POWER CO
Changes in fair value, tax	(19)	24	(3)	20
Reclassification adjustment for cash flow hedge, gain (loss), tax	20	(27)	12	(30)
Reclassification adjustment for pension and other post retirement benefit plans, tax	0	0	0	0
SOUTHERN Co GAS
Changes in fair value, tax	0	(1)	0	(2)
Reclassification adjustment for cash flow hedge, gain (loss), tax	0	0	1	0
Reclassification adjustment for pension and other post retirement benefit plans, tax	$ 0	$ 0	$ 0	$ 0