ACQUISITIONS AND DISPOSITIONS - SO Dispositions Narrative (Details) - USD ($)			3 Months Ended				12 Months Ended
	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 30, 2019	Jul. 22, 2019
Business Acquisition [Line Items]
Gain (loss) on dispositions							$ (2,569,000,000)	$ (291,000,000)	$ (40,000,000)
Impairment charges			$ 0
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	70,000,000	$ 4,000,000	$ (15,000,000)	$ 2,500,000,000	2,600,000,000
Gain on dispositions, after tax		$ 1,400,000,000	102,000,000	4,000,000	(11,000,000)	$ 1,300,000,000	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 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 | Leveraged Lease Investment
Business Acquisition [Line Items]
Consideration for sale										$ 20,000,000
Disposal Group, Held-for-sale, Not Discontinued Operations | PowerSecure International, Inc. Lighting Business
Business Acquisition [Line Items]
Impairment charges				2,000,000
Goodwill and Intangible Asset Impairment				$ 18,000,000