v3.26.1
Cover Page
shares in Thousands
3 Months Ended
Mar. 31, 2026
shares
Cover [Abstract]  
Document Type 10-Q
Document Quarterly Report true
Document Period End Date Mar. 31, 2026
Document Transition Report false
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
Entity Current Reporting Status Yes
Entity Interactive Data Current Yes
Entity Filer Category Non-accelerated Filer
Entity Small Business false
Entity Emerging Growth Company false
Entity Shell Company false
Entity Common Stock Shares Outstanding 0
Entity Central Index Key 0002038118
Current Fiscal Year End Date --12-31
Document Fiscal Year Focus 2026
Document Fiscal Period Focus Q1
Amendment Flag false