Quarterly Financial Information (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Summarized quarterly financial information
Operating revenues	$ 3,703,000	$ 5,049,000	$ 4,181,000	$ 3,604,000	$ 3,696,000	$ 5,428,000	$ 4,521,000	$ 4,012,000	$ 16,537,000		$ 17,657,000		$ 17,456,000
Operating Income	814,000	1,740,000	1,143,000	766,000	589,000	1,652,000	1,136,000	854,000	4,463,000		4,231,000		3,802,000
Net Income After Dividends on Preferred and Preference Stock	383,000	976,000	623,000	368,000	261,000	916,000	604,000	422,000	2,350,000	[1]	2,203,000	[1]	1,975,000	[1]
Basic Earnings	$ 0.44	$ 1.11	$ 0.71	$ 0.42	$ 0.30	$ 1.07	$ 0.71	$ 0.50	$ 2.70		$ 2.57		$ 2.37
Dividends	$ 0.49	$ 0.4900	$ 0.4900	$ 0.4725	$ 0.4725	$ 0.4725	$ 0.4725	$ 0.4550	$ 1.9425		$ 1.8725		$ 1.8025
Trading price range per common share high	$ 47.09	$ 48.59	$ 48.45	$ 46.06	$ 46.69	$ 43.09	$ 40.87	$ 38.79
Trading price range per common share low	$ 41.75	$ 44.64	$ 44.22	$ 43.71	$ 41	$ 35.73	$ 37.43	$ 36.51
Southern Power [Member]
Summarized quarterly financial information
Operating revenues	291,591	354,971	285,805	253,681	286,400	362,565	305,209	281,787	1,186,048		1,235,961		1,130,341
Operating Income	65,816	119,234	90,038	56,343	63,604	108,708	86,792	77,347	331,431		336,451		282,861
Net Income After Dividends on Preferred and Preference Stock	30,991	68,376	46,602	29,316	23,816	56,071	44,601	37,743
Mississippi Power [Member]
Summarized quarterly financial information
Operating revenues	235,779	305,419	266,084	228,714	237,794	325,766	286,041	263,276	1,035,996		1,112,877		1,143,068
Operating Income	31,662	66,151	46,986	30,213	16,412	53,171	39,056	25,151	175,012		133,790		142,818
Net Income After Dividends on Preferred and Preference Stock	33,200	54,625	35,027	25,255	16,263	38,019	25,283	14,617	148,107		94,182		80,217
Alabama Power [Member]
Summarized quarterly financial information
Operating revenues	1,290,000	1,637,000	1,377,000	1,216,000	1,271,000	1,671,000	1,440,000	1,320,000	5,520,000		5,702,000		5,976,000
Operating Income	271,000	544,000	390,000	291,000	258,000	523,000	404,000	329,000	1,496,000		1,514,000		1,489,000
Net Income After Dividends on Preferred and Preference Stock	113,000	280,000	185,000	126,000	102,000	264,000	190,000	152,000	704,000		708,000		707,000
Georgia Power [Member]
Summarized quarterly financial information
Operating revenues	1,735,000	2,498,000	2,020,000	1,745,000	1,758,000	2,788,000	2,265,000	1,989,000	7,998,000		8,800,000		8,349,000
Operating Income	400,000	924,000	535,000	344,000	222,000	895,000	537,000	393,000	2,203,000		2,047,000		1,665,000
Net Income After Dividends on Preferred and Preference Stock	181,000	525,000	295,000	167,000	110,000	520,000	309,000	206,000	1,168,000		1,145,000		950,000
Gulf Power [Member]
Summarized quarterly financial information
Operating revenues	331,490	421,819	370,208	316,245	327,909	468,030	399,265	324,608	1,439,762		1,519,812		1,590,209
Operating Income	53,818	93,813	71,465	49,098	43,839	81,454	67,387	32,044	268,194		224,724		246,800
Net Income After Dividends on Preferred and Preference Stock	$ 22,549	$ 47,754	$ 34,963	$ 20,666	$ 18,745	$ 41,217	$ 33,352	$ 11,691	$ 125,932		$ 105,005		$ 121,511

[1] *After dividends on preferred and preference stock of subsidiaries.