ACQUISITIONS AND DISPOSITIONS - Southern Company Narrative (Details)			1 Months Ended		3 Months Ended							12 Months Ended
	Dec. 13, 2021 USD ($) project	Oct. 29, 2021 USD ($)	Dec. 31, 2019 USD ($) leveraged_lease	Jan. 31, 2019 USD ($)	Dec. 31, 2021 USD ($)	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2021 USD ($) project	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 30, 2019 USD ($)	Jul. 31, 2019 USD ($)
Business Acquisition [Line Items]
Gain (loss) on dispositions												$ 176,000,000	$ 66,000,000	$ 2,588,000,000
Impairment charges					$ 0
Number of domestic projects subject to leveraged lease sold | project												1
Lease, initial impairment loss							$ 34,000,000
Lease, initial impairment loss, after tax							17,000,000
Lease, impairment loss								$ 154,000,000	$ 17,000,000			$ 7,000,000	206,000,000	0
Lease, impairment loss, after tax								$ 74,000,000	13,000,000
Proceeds from sale of assets subject to leveraged lease	$ 673,000,000	$ 45,000,000
Gain (loss) on sale of assets subject to leveraged lease		$ 0
Leveraged leases, income tax benefits					$ 16,000,000
Number of international projects subject to leveraged lease terminated | project	2											2
Gain (loss) on termination of leveraged leases												$ 93,000,000
Gain (loss) on termination of leveraged leases, after tax												$ 99,000,000
All Other
Business Acquisition [Line Items]
Lease, impairment loss						$ 7,000,000	18,000,000						206,000,000
Lease, impairment loss, after tax						$ 6,000,000	$ 14,000,000						$ 105,000,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Gulf Power
Business Acquisition [Line Items]
Cash proceeds from sale of business				$ 5,800,000,000
Indebtedness assumed				1,300,000,000
Gain (loss) on dispositions				2,600,000,000										2,600,000,000
Gain (loss) on dispositions, after tax				$ 1,400,000,000										1,400,000,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | PowerSecure Utility Infrastructure Services Unit
Business Acquisition [Line Items]
Consideration for sale																$ 65,000,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | PowerSecure International, Inc. Lighting Business
Business Acquisition [Line Items]
Cash proceeds from sale of business			$ 4,000,000
Indebtedness assumed			5,000,000						5,000,000					5,000,000
Gain (loss) on dispositions														(58,000,000)
Gain (loss) on dispositions, after tax														(52,000,000)
Consideration for sale			$ 9,000,000						$ 9,000,000					$ 9,000,000
Disposal Group, Held-for-sale, Not Discontinued Operations | PowerSecure Utility Infrastructure Services Unit
Business Acquisition [Line Items]
Impairment charges											$ 32,000,000
Disposal Group, Held-for-sale, Not Discontinued Operations | PowerSecure International, Inc. Lighting Business
Business Acquisition [Line Items]
Goodwill and intangible asset impairment										$ 18,000,000
Disposal Group, Held-for-sale, Not Discontinued Operations | Leveraged Lease Investment
Business Acquisition [Line Items]
Consideration for sale															$ 20,000,000
Number of domestic projects subject to leveraged lease sold | leveraged_lease			1