Introduction - Asset Retirement Obligations (Details) $ in Millions	6 Months Ended
	Jun. 30, 2016 USD ($)
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year	$ 3,759
Liabilities incurred	9
Liabilities settled	(66)
Accretion	77
Cash flow revisions	699
Balance at end of period	4,478
Alabama Power [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year	1,448
Liabilities incurred	5
Liabilities settled	(6)
Accretion	36
Cash flow revisions	19
Balance at end of period	$ 1,502
Georgia Power [Member]
Property, Plant and Equipment [Line Items]
Asset Retirement Obligation, Period Of Update Cycle	3 years
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year	$ 1,916
Liabilities incurred	0
Liabilities settled	(52)
Accretion	34
Cash flow revisions	673
Balance at end of period	2,571
Gulf Power [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year	130
Liabilities incurred	0
Liabilities settled	(1)
Accretion	1
Cash flow revisions	3
Balance at end of period	133
Mississippi Power [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year	177
Liabilities incurred	0
Liabilities settled	(7)
Accretion	2
Cash flow revisions	6
Balance at end of period	178
Southern Power [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year	21
Liabilities incurred	4
Liabilities settled	0
Accretion	1
Cash flow revisions	2
Balance at end of period	$ 28