ACQUISITIONS AND DISPOSITIONS - GAS Acquisitions and Dispositions Narrative (Details) - Southern Company Gas $ in Millions	1 Months Ended	3 Months Ended	12 Months Ended
	Jul. 31, 2021 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Sep. 30, 2022 USD ($) storageFacility
Business Acquisition [Line Items]
Gain (loss) on dispositions			$ 7	$ 4	$ 127
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Sequent
Business Acquisition [Line Items]
Consideration for sale	$ 159
Gain (loss) on dispositions	121		121		121
Gain (loss) on dispositions, after tax	92		92		92
Deferred tax expense, increase from change in appointment rate	$ 85		$ 85		$ 85
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Natural Gas Storage Facilities
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