ACQUISITIONS AND DISPOSITIONS - GAS Acquisitions and Dispositions Narrative (Details) $ in Millions		1 Months Ended			3 Months Ended	6 Months Ended		12 Months Ended
	Jul. 01, 2021 USD ($)	Jul. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Mar. 31, 2020 USD ($) payment	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Sep. 07, 2022 USD ($) storageFacility	May 31, 2022 USD ($)	Apr. 22, 2021 USD ($)
Business Acquisition [Line Items]
Gain (loss) on dispositions								$ 42	$ 176	$ 66
Southern Company Gas
Business Acquisition [Line Items]
Gain (loss) on dispositions								4	$ 127	$ 22
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Sequent | Southern Company Gas
Business Acquisition [Line Items]
Consideration for sale	$ 159
Gain (loss) on dispositions	121							121
Gain (loss) on dispositions, after tax	$ 92							92
Deferred tax expense, increase from change in appointment rate		$ 85				$ 85	$ 85	$ 85
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Pivotal LNG | Southern Company Gas
Business Acquisition [Line Items]
Cash proceeds from sale of business				$ 178
Number of contingent milestone payments | payment				2
Contingent milestone payment, amount												$ 5	$ 5
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Jefferson Island | Southern Company Gas | Natural Gas Storage Facility
Business Acquisition [Line Items]
Gain (loss) on dispositions			$ 22
Gain (loss) on dispositions, after tax			16
Cash proceeds from sale of business			$ 33
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Natural Gas Storage Facilities | Southern Company Gas
Business Acquisition [Line Items]
Consideration for sale											$ 186
Gain (loss) on dispositions					$ (131)
Gain (loss) on dispositions, after tax					$ (99)
Number of natural gas storage facilities sold | storageFacility											2