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INCOME TAXES - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2025	Mar. 31, 2024	Mar. 25, 2024	Dec. 31, 2023
Provision For Income Tax [Line Items]
Operating Loss Carryforwards				$ 8,100
Deferred tax liabilities, net		$ 46
Reduction to OPIC		$ 803
Forecast
Provision For Income Tax [Line Items]
Operating loss carryforwards, subject to expiration	$ 1,600
North American Transmission Company II LLC | FET
Provision For Income Tax [Line Items]
Tax gain from combined sale			$ 7,000
Sale of ownership interest by parent		19.90%	49.90%

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Deferred Tax assets, Federal And State Income Tax Associated With The Tax Gain

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards that are subject to expiration dates.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-6

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Amount, after deferred tax asset, of deferred tax liability attributable to taxable differences without jurisdictional netting.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-2

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Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
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