Condensed Consolidated Statements of Comprehensive Income (Unaudited) - GAS (Parenthetical) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Changes in fair value, tax	$ 8	$ (10)
Qualifying hedges, reclassification adjustment, tax	6	18
SOUTHERN Co GAS
Changes in fair value, tax	10	0
Qualifying hedges, reclassification adjustment, tax	$ (2)	$ 1

Amount of tax expense (benefit) for reclassification of gain (loss) from accumulated other comprehensive income (AOCI) for derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=124509347&loc=d3e640-108580

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration