Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Consolidated Net Income	$ 665	$ 501
Qualifying hedges:
Changes in fair value, net of tax	(9)	(117)
Reclassification adjustment for amounts included in net income, net of tax	(1)	2
Pension and other post retirement benefit plans:
Reclassification adjustment for amounts included in net income, net of tax	1	1
Total other comprehensive income (loss)	(9)	(114)
Dividends on preferred and preference stock of subsidiaries	11	11
Comprehensive income (loss) attributable to noncontrolling interests	(4)	1
Consolidated Comprehensive Income Attributable to Southern Company	649	375
Alabama Power [Member]
Consolidated Net Income	178	160
Qualifying hedges:
Changes in fair value, net of tax	0	(2)
Reclassification adjustment for amounts included in net income, net of tax	1	1
Pension and other post retirement benefit plans:
Total other comprehensive income (loss)	1	(1)
Dividends on preferred and preference stock of subsidiaries	4	4
Consolidated Comprehensive Income Attributable to Southern Company	179	159
Georgia Power [Member]
Consolidated Net Income	264	273
Qualifying hedges:
Changes in fair value, net of tax	0	0
Reclassification adjustment for amounts included in net income, net of tax	1	1
Pension and other post retirement benefit plans:
Total other comprehensive income (loss)	1	1
Dividends on preferred and preference stock of subsidiaries	4	4
Consolidated Comprehensive Income Attributable to Southern Company	265	274
Gulf Power [Member]
Consolidated Net Income	20	31
Qualifying hedges:
Changes in fair value, net of tax	(1)	(3)
Pension and other post retirement benefit plans:
Total other comprehensive income (loss)	(1)	(3)
Dividends on preferred and preference stock of subsidiaries	2	2
Consolidated Comprehensive Income Attributable to Southern Company	19	28
Mississippi Power [Member]
Consolidated Net Income	(20)	11
Qualifying hedges:
Changes in fair value, net of tax	1	0
Pension and other post retirement benefit plans:
Total other comprehensive income (loss)	1	0
Dividends on preferred and preference stock of subsidiaries	0	0
Consolidated Comprehensive Income Attributable to Southern Company	(19)	11
Southern Power [Member]
Consolidated Net Income	66	51
Qualifying hedges:
Changes in fair value, net of tax	(8)	0
Reclassification adjustment for amounts included in net income, net of tax	(4)	1
Pension and other post retirement benefit plans:
Total other comprehensive income (loss)	(12)	1
Comprehensive income (loss) attributable to noncontrolling interests	(4)	1
Consolidated Comprehensive Income Attributable to Southern Company	58	51
Southern Company Gas [Member]
Consolidated Net Income	239
Qualifying hedges:
Changes in fair value, net of tax	(1)
Reclassification adjustment for amounts included in net income, net of tax	0
Pension and other post retirement benefit plans:
Reclassification adjustment for amounts included in net income, net of tax	(1)
Total other comprehensive income (loss)	(2)
Comprehensive income (loss) attributable to noncontrolling interests	0
Consolidated Comprehensive Income Attributable to Southern Company	$ 237
Predecessor [Member] | Southern Company Gas [Member]
Consolidated Net Income		193
Qualifying hedges:
Changes in fair value, net of tax		(29)
Reclassification adjustment for amounts included in net income, net of tax		(1)
Pension and other post retirement benefit plans:
Reclassification adjustment for amounts included in net income, net of tax		3
Total other comprehensive income (loss)		(27)
Comprehensive income (loss) attributable to noncontrolling interests		11
Consolidated Comprehensive Income Attributable to Southern Company		$ 155