Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 942
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Name:	us-gaap_Goodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Goodwill Balances (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Goodwill	$ 5,280	$ 5,280	$ 5,280
Southern Company Gas
Goodwill [Line Items]
Goodwill	5,015	5,015
Gas distribution operations \| Southern Company Gas
Goodwill [Line Items]
Goodwill	4,034	4,034
Gas marketing services \| Southern Company Gas
Goodwill [Line Items]
Goodwill	$ 981	$ 981