Introduction - Asset Retirement Obligations (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year		$ 2,201
Liabilities incurred		644
Liabilities settled		(19)
Accretion		83
Cash flow revisions		214
Balance at end of period	$ 3,123	3,123
Alabama Power [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year		829
Liabilities incurred		402
Liabilities settled		(1)
Accretion		38
Cash flow revisions		20
Balance at end of period	1,288	1,288
Georgia Power [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year		1,255
Liabilities incurred		0
Liabilities settled		(18)
Accretion		42
Cash flow revisions		193
Balance at end of period	1,472	1,472
Gulf Power [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year		17
Liabilities incurred	30	101
Liabilities settled		0
Accretion		1
Cash flow revisions		3
Balance at end of period	122	122
Mississippi Power [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year		48
Liabilities incurred		97
Liabilities settled		0
Accretion		2
Cash flow revisions		25
Balance at end of period	$ 172	$ 172