Stockholders' Equity - Changes in Stockholders' Equity (Details) - USD ($) shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Changes in Stockholders' Equity
Beginning Balance, Treasury Shares			(3,400)
Beginning Balance			$ 21,982	$ 20,926
Consolidated net income attributable to Southern Company	$ 612	$ 629	1,097	1,138
Other comprehensive income (loss)	$ (3)	22	(117)	7
Stock issued			1,383	117
Stock-based compensation			82	66
Stock repurchased, at cost				(115)
Cash dividends on common stock			(1,023)	(972)
Preference stock redemption				(150)
Contributions from noncontrolling interests			169	135
Distributions to noncontrolling interests			(10)	(5)
Purchase of membership interests from noncontrolling interests			(129)
Net income attributable to noncontrolling interests			11	4
Other			$ 1	(5)
Beginning Balance, Treasury Shares	(800)		(800)
Ending Balance	$ 23,446	$ 21,146	$ 23,446	$ 21,146
Noncontrolling Interest in Preferred Unit Holders	609		609		$ 609
Nonredeemable Noncontrolling Interest	$ 822		$ 822		$ 781
Number of Common shares Issued [Member]
Changes in Stockholders' Equity
Beginning Balance, Shares			915,073	908,502
Stock issued, Shares			27,297	3,222
Ending Balance, Shares	942,370	911,724	942,370	911,724
Number of Common shares Treasury [Member]
Changes in Stockholders' Equity
Beginning Balance, Treasury Shares			(3,352)	(725)
Stock issued, Shares			2,599
Stock repurchased, at cost, Shares				(2,599)
Other, Shares			(19)	25
Beginning Balance, Treasury Shares	(772)	(3,299)	(772)	(3,299)
Common Stockholders' Equity [Member]
Changes in Stockholders' Equity
Beginning Balance			$ 20,592	$ 19,949
Consolidated net income attributable to Southern Company			1,097	1,138
Other comprehensive income (loss)			(117)	7
Stock issued			1,383	117
Stock-based compensation			82	66
Stock repurchased, at cost				(115)
Cash dividends on common stock			(1,023)	(972)
Other			1	(8)
Ending Balance	$ 22,015	$ 20,182	22,015	20,182
Preferred And Preference Stock [Member]
Changes in Stockholders' Equity
Beginning Balance			609	756
Preference stock redemption				(150)
Other				3
Ending Balance	609	609	609	609
Noncontrolling Interest [Member]
Changes in Stockholders' Equity
Beginning Balance			781	221
Contributions from noncontrolling interests			169	135
Distributions to noncontrolling interests			(10)	(5)
Purchase of membership interests from noncontrolling interests			(129)
Net income attributable to noncontrolling interests			11	4
Ending Balance	$ 822	$ 355	$ 822	$ 355