INCOME TAXES - Narrative (Details) - USD ($)	Mar. 31, 2024	Mar. 25, 2024	Dec. 31, 2023	Aug. 16, 2022	May 31, 2022
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Operating loss carryforwards, not subject to expiration, net of tax				$ 1,000,000,000
Operating loss carryforwards, subject to expiration			$ 8,100,000,000
Deferred tax liabilities, net	$ 46,000,000
Reduction to OPIC	$ 797,000,000
North American Transmission Company II LLC | FET
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Operating loss carryforwards, subject to expiration		$ 7,300,000,000
Sale of ownership interest by parent		49.90%			19.90%