Income Taxes - Current and Deferred Income Tax Provisions (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Federal -
Current	$ 175,000	$ 363,000	$ 177,000
Deferred	695,000	386,000	1,011,000
Total federal taxes	870,000	749,000	1,188,000
State -
Current	93,000	(10,000)	61,000
Deferred	14,000	110,000	85,000
Total state taxes	107,000	100,000	146,000
Income taxes	977,000	849,000	1,334,000
Alabama Power [Member]
Federal -
Current	198,000	243,000	262,000
Deferred	225,000	160,000	137,000
Total federal taxes	423,000	403,000	399,000
State -
Current	44,000	36,000	51,000
Deferred	45,000	39,000	27,000
Total state taxes	89,000	75,000	78,000
Income taxes	512,000	478,000	477,000
Georgia Power [Member]
Federal -
Current	295,000	277,000	273,000
Deferred	366,000	374,000	370,000
Total federal taxes	661,000	651,000	643,000
State -
Current	82,000	(30,000)	38,000
Deferred	(14,000)	102,000	7,000
Total state taxes	68,000	72,000	45,000
Income taxes	729,000	723,000	688,000
Gulf Power [Member]
Federal -
Current	22,771	5,009	(92,610)
Deferred	52,602	63,134	161,096
Total federal taxes	75,373	68,143	68,486
State -
Current	(39)	(2,410)	(2,484)
Deferred	12,728	13,935	13,209
Total state taxes	12,689	11,525	10,725
Income taxes	88,062	79,668	79,211
Mississippi Power [Member]
Federal -
Current	(431,077)	23,345	1,212
Deferred	183,461	(342,870)	16,994
Total federal taxes	(247,616)	(319,525)	18,206
State -
Current	455	5,219	1,656
Deferred	(38,044)	(53,529)	694
Total state taxes	(37,589)	(48,310)	2,350
Income taxes	(285,205)	(367,835)	20,556
Southern Power [Member]
Federal -
Current	178,600	(120,200)	(133,100)
Deferred	(166,000)	158,700	210,400
Total federal taxes	12,600	38,500	77,300
State -
Current	(13,800)	(5,200)	(3,000)
Deferred	(2,000)	12,600	18,300
Total state taxes	(15,800)	7,400	15,300
Income taxes	$ (3,228)	$ 45,895	$ 92,621