Income Taxes (Tables)

9 Months Ended

Sep. 30, 2016

Income Tax Disclosure [Abstract]

Change in Unrecognized Tax Benefits

Changes during 2016 for unrecognized tax benefits were as follows:

	Mississippi Power		Southern Power			Southern Company
	(in millions)
Unrecognized tax benefits as of December 31, 2015	$	421	$	8		$	433
Tax positions from current periods	—		12			12
Tax positions from prior periods	18		(1		)	13
Balance as of September 30, 2016	$	439	$	19		$	458

Impact on Effective Tax Rate, If Recognized

The impact on the effective tax rate, if recognized, is as follows:

	As of September 30, 2016						As of December 31, 2015
	Mississippi Power		Southern Power		Southern Company		Southern Company
	(in millions)
Tax positions impacting the effective tax rate	$	1	$	19	$	20	$	10
Tax positions not impacting the effective tax rate	438		—		438		423
Balance of unrecognized tax benefits	$	439	$	19	$	458	$	433