v3.26.3
DocumentAndEntityInformation
Oct. 21, 2026
Document Information Line Items  
Entity Central Index Key 0000357301
Document Type 8-K
Document Period End Date Oct. 21, 2026
Entity Registrant Name TrustCo Bank Corp NY
Entity Incorporation, State or Country Code NY
Entity File Number 0-10592
Entity Tax Identification Number 14-1630287
Entity Address, Address Line One 5 SARNOWSKI DRIVE
Entity Address, City or Town GLENVILLE
Entity Address, State or Province NY
Entity Address, Postal Zip Code 12302
City Area Code 518
Local Phone Number 377-3311
Written Communications false
Soliciting Material false
Pre-commencement Tender Offer false
Pre-commencement Issuer Tender Offer false
Title of 12(b) Security Common Stock, $1.00 par value
Trading Symbol TRST
Security Exchange Name NASDAQ
Entity Emerging Growth Company false
Amendment Flag false