Accumulated Provisions for Decommissioning.

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Amount expensed for rate making purpose.

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Fair market value of fund's securities on loan under fund's managers securities lending program.

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Fair value of collateral received amount.

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Significant Assumption Of Inflation Rate Used To Determine Costs For Rate Making

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Significant Assumption Of Trust Earnings Rate Used To Determine Costs For Rate Making

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- Definition

Amount of increase (decrease) in asset retirement obligations.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

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Amount of increase (decrease) in the asset retirement obligation from changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
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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.

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ASSET RETIREMENT OBLIGATIONS - Narrative (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Jointly Owned Utility Plant Interests [Line Items]
Cash flow revisions			$ 1,026	$ 912
Alabama Power
Jointly Owned Utility Plant Interests [Line Items]
Increase to AROs				501
Cash flow revisions			$ 406	501
Estimated inflation rate			4.50%
Estimated trust earnings rate			7.00%
Alabama Power \| Internal reserves
Jointly Owned Utility Plant Interests [Line Items]
Accumulated provisions for decommissioning			$ 15	15
Georgia Power
Jointly Owned Utility Plant Interests [Line Items]
Increase to AROs		$ 411
Cash flow revisions	$ 435		530	418
Fair market value of securities on loan and pledged to creditors			42	44
Fair value of collateral received			$ 43	45
Estimated inflation rate			2.50%
Estimated trust earnings rate			4.50%
Georgia Power \| Plant Hatch and Plant Vogtle Units 1 And 2
Jointly Owned Utility Plant Interests [Line Items]
Annual decommissioning cost for ratemaking				4	$ 5
Mississippi Power
Jointly Owned Utility Plant Interests [Line Items]
Cash flow revisions	$ 31		$ 31	$ 0