Stockholders' Equity - Changes in Stockholders' Equity (Details) - USD ($) shares in Thousands, $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	May 31, 2017	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Changes in Stockholders' Equity
Beginning balance, treasury shares (in shares)				(800)
Beginning balance				$ 26,612	$ 21,982
Consolidated net income (loss) attributable to Southern Company		$ (1,381)	$ 623	(723)	1,112
Other comprehensive income (loss)				(11)	(117)
Stock issued				417	1,383
Stock-based compensation				72	67
Cash dividends on common stock				(1,134)	(1,023)
Preference stock redemption				(150)
Contributions from noncontrolling interests				71	169
Distributions to noncontrolling interests				(40)	(10)
Purchase of membership interests from noncontrolling interests					(129)
Net income attributable to noncontrolling interests				16	11
Reclassification from redeemable noncontrolling interests				114
Other				$ (3)	1
Ending balance, treasury shares (in shares)		(900)		(900)
Ending balance		$ 25,241	$ 23,446	$ 25,241	$ 23,446
Number of Common Shares Issued
Changes in Stockholders' Equity
Beginning balance (in shares)				991,213	915,073
Stock issued (in shares)				9,129	27,297
Other (in shares)				0
Ending balance (in shares)		1,000,342	942,370	1,000,342	942,370
Number of Common Shares Treasury Issued
Changes in Stockholders' Equity
Beginning balance, treasury shares (in shares)				(819)	(3,352)
Stock issued (in shares)				0	2,599
Other (in shares)				(49)	(19)
Ending balance, treasury shares (in shares)		(868)	(772)	(868)	(772)
Common Stockholders' Equity
Changes in Stockholders' Equity
Beginning balance				$ 24,758	$ 20,592
Consolidated net income (loss) attributable to Southern Company				(723)	1,112
Other comprehensive income (loss)				(11)	(117)
Stock issued				417	1,383
Stock-based compensation				72	67
Cash dividends on common stock				(1,134)	(1,023)
Other				(7)	1
Ending balance		$ 23,372	$ 22,015	23,372	22,015
Preferred and Preference Stock of Subsidiaries
Changes in Stockholders' Equity
Beginning balance				609	609
Preference stock redemption				(150)
Other				3
Ending balance		462	609	462	609
Noncontrolling Interest
Changes in Stockholders' Equity
Beginning balance				1,245	781
Contributions from noncontrolling interests				71	169
Distributions to noncontrolling interests				(40)	(10)
Purchase of membership interests from noncontrolling interests					(129)
Net income attributable to noncontrolling interests				16	11
Reclassification from redeemable noncontrolling interests				114
Other				1
Ending balance		$ 1,407	$ 822	$ 1,407	$ 822
SunPower Corp. | Noncontrolling Interest
Changes in Stockholders' Equity
Beginning balance	$ 114