Derivatives - Balance Sheet Offsetting (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 27,000		$ 36,000
Derivative Liability, Fair Value, Gross Liability	56,000		111,000
Alabama Power [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	7,000		5,000
Derivative Liability, Fair Value, Gross Liability	8,000		18,000
Mississippi Power [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	4,803		2,519
Derivative Liability, Fair Value, Gross Liability	10,282		19,483
Energy Related Derivative [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Amount Offset Against Collateral	2,000		3,000
Derivative Liability, Fair Value, Amount Offset Against Collateral	34,000		88,000
Energy Related Derivative [Member] | Alabama Power [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Amount Offset Against Collateral	2,000		1,000
Derivative Liability, Fair Value, Amount Offset Against Collateral	3,000		14,000
Energy Related Derivative [Member] | Georgia Power [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Amount Offset Against Collateral	0		0
Derivative Liability, Fair Value, Amount Offset Against Collateral	16,000		34,000
Energy Related Derivative [Member] | Gulf Power [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Amount Offset Against Collateral	1,000		0
Derivative Liability, Fair Value, Amount Offset Against Collateral	11,000		23,000
Energy Related Derivative [Member] | Mississippi Power [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Amount Offset Against Collateral	947		186
Derivative Liability, Fair Value, Amount Offset Against Collateral	6,425		17,113
Energy Related Derivative [Member] | Southern Power [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	600		2,100
Derivative Asset, Fair Value, Amount Offset Against Collateral	500		1,100
Derivative Liability, Fair Value, Gross Liability	600		1,300
Derivative Liability, Fair Value, Amount Offset Against Collateral	500		300
Net Amount Of Derivatives [Member] | Energy Related Derivative [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	24,000	[1]	26,000	[1]
Derivative Liability, Fair Value, Gross Liability	56,000	[1]	111,000	[1]
Net Amount Of Derivatives [Member] | Energy Related Derivative [Member] | Alabama Power [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	7,000	[1]	5,000	[1]
Derivative Liability, Fair Value, Gross Liability	8,000	[1]	18,000	[1]
Net Amount Of Derivatives [Member] | Energy Related Derivative [Member] | Georgia Power [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	5,000	[1]	11,000	[1]
Derivative Liability, Fair Value, Gross Liability	21,000	[1]	45,000	[1]
Net Amount Of Derivatives [Member] | Energy Related Derivative [Member] | Gulf Power [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	7,000	[1]	4,000	[1]
Derivative Liability, Fair Value, Gross Liability	17,000	[1]	27,000	[1]
Net Amount Of Derivatives [Member] | Energy Related Derivative [Member] | Mississippi Power [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	4,803	[1]	2,519	[1]
Derivative Liability, Fair Value, Gross Liability	10,281	[1]	19,446	[1]
Net Amount Of Derivatives [Member] | Energy Related Derivative [Member] | Southern Power [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	600	[1]	2,100	[1]
Derivative Liability, Fair Value, Gross Liability	600	[1]	1,300	[1]
Gross Amount Of Derivatives [Member] | Energy Related Derivative [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	(22,000)	[2]	(23,000)	[2]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	(22,000)	[2]	(23,000)	[2]
Gross Amount Of Derivatives [Member] | Energy Related Derivative [Member] | Alabama Power [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	(5,000)	[2]	(4,000)	[2]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	(5,000)	[2]	(4,000)	[2]
Gross Amount Of Derivatives [Member] | Energy Related Derivative [Member] | Georgia Power [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	(5,000)	[2]	(11,000)	[2]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	(5,000)	[2]	(11,000)	[2]
Gross Amount Of Derivatives [Member] | Energy Related Derivative [Member] | Gulf Power [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	(6,000)	[3]	(4,000)	[3]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	(6,000)	[3]	(4,000)	[3]
Gross Amount Of Derivatives [Member] | Energy Related Derivative [Member] | Mississippi Power [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	(3,856)	[2]	(2,333)	[2]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	(3,856)	[2]	(2,333)	[2]
Gross Amount Of Derivatives [Member] | Energy Related Derivative [Member] | Southern Power [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	(100)	[2]	(1,000)	[2]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	$ (100)	[2]	$ (1,000)	[2]

[1] The Company does not offset fair value amounts for multiple derivative instruments executed with the same counterparty on the balance sheets; therefore, gross and net amounts of derivative assets and liabilities presented on the balance sheets are the same.

[2] Includes gross amounts subject to netting terms that are not offset on the balance sheets and any cash/financial collateral pledged or received.

[3] (b) Includes gross amounts subject to netting terms that are not offset on the balance sheets and any cash/financial collateral pledged or received.