Condensed Consolidated Statements of Cash Flows (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Interest capitalized	$ 21	$ 20
ALABAMA POWER CO
Interest capitalized	3	3
GEORGIA POWER CO
Interest capitalized	15	11
MISSISSIPPI POWER CO
Interest capitalized	0	0
SOUTHERN POWER CO
Interest capitalized	1	4
SOUTHERN Co GAS
Interest capitalized	$ 2	$ 2

Amount of cash paid for interest capitalized, classified as investing activity.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3213-108585

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121583591&loc=d3e4297-108586

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration