v3.26.3
Cover Page
Oct. 23, 2026
Cover [Abstract]  
Document Type 8-K
Document Period End Date Oct. 23, 2026
Entity File Number 333-282554
Entity Registrant Name FIRSTENERGY TRANSMISSION, LLC
Entity Tax Identification Number 20-5763884
Entity Incorporation, State or Country Code DE
Entity Address, Address Line One 5001 NASA Boulevard
Entity Address, City or Town Fairmont
Entity Address, State or Province WV
Entity Address, Postal Zip Code 26554
City Area Code (800)
Local Phone Number 736-3402
Written Communications false
Soliciting Material false
Pre-commencement Tender Offer false
Pre-commencement Issuer Tender Offer false
Entity Emerging Growth Company false
Entity Central Index Key 0002038118
Amendment Flag false