Expected volume of natural gas subject to option to sell back excess gas due to operational constraints.

No definition available.

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- Definition

The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=35736893&loc=d3e80748-113994

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- Definition

The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4H
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624258-113959

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

The estimated net amount of unrealized gains or losses on foreign currency cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

+ References

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Derivatives - Narrative (Details) MMBTU in Millions	9 Months Ended
Derivatives - Narrative (Details) MMBTU in Millions	Sep. 30, 2017 USD ($) MMBTU	Dec. 31, 2016 USD ($)
Derivative [Line Items]
Collateral already posted, aggregate fair value	$ 76,000,000
Southern Company
Derivative [Line Items]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints \| MMBTU	34
Cash flow hedge gain (loss) to be reclassified within twelve months	$ (19,000,000)
GEORGIA POWER CO
Derivative [Line Items]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints \| MMBTU	11
ALABAMA POWER CO
Derivative [Line Items]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints \| MMBTU	5
Gulf Power and Mississippi Power
Derivative [Line Items]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints \| MMBTU	3
MISSISSIPPI POWER CO
Derivative [Line Items]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints \| MMBTU	4
SOUTHERN POWER CO
Derivative [Line Items]
Cash flow hedge gain (loss) to be reclassified within twelve months	$ 5,000,000
Parent Company and Southern Power
Derivative [Line Items]
Foreign currency cash flow hedge gain (loss) to be reclassified during next 12 months	(23,000,000)
SOUTHERN Co GAS
Derivative [Line Items]
Collateral already posted, aggregate fair value	76,000,000	$ 62,000,000
Derivative Counterparties \| Registrants
Derivative [Line Items]
Collateral already posted, aggregate fair value	$ 0