Derivatives - Contingent Features (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013
Derivatives, Fair Value [Line Items]
Derivative liabilities	$ 1
Alabama Power [Member]
Derivatives, Fair Value [Line Items]
Derivative liabilities	0
Georgia Power [Member]
Derivatives, Fair Value [Line Items]
Derivative liabilities	2
Gulf Power [Member]
Derivatives, Fair Value [Line Items]
Derivative liabilities	0
Mississippi Power [Member]
Derivatives, Fair Value [Line Items]
Derivative liabilities	0
Southern Power [Member]
Derivatives, Fair Value [Line Items]
Derivative liabilities	$ 0

The amount as of the balance sheet date of the fair value of derivative liabilities that in accordance with the entity's accounting policy was not offset against the right to reclaim cash collateral under a master netting arrangement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 8

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=d3e41678-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FIN39-1

-Paragraph 10B

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant