Document and Entity Information	6 Months Ended
	Jun. 30, 2012	Jul. 31, 2012
Document and Entity Information [Abstract]
Entity Registrant Name	TRUSTCO BANK CORP N Y
Entity Central Index Key	0000357301
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		93,807,298
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q2
Document Type	10-Q
Amendment Flag	true
Amendment Description	The sole purpose of this amendment to our Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2012, originally filed with the Securities and Exchange Commission on August 3, 2012, is to correct Exhibit 101 to the Form 10-Q which contains the XBRL (eXtensible Business Reporting Language) Interactive Data File. The error was related to an incorrect detail tag in the Florida impaired loan table. Total Florida impaired loans as of June 30, 2012 were incorrectly tagged to the Florida “Residential 1 to 4 family” line item in that table. No changes have been made to the Form 10-Q other than the furnishing revised Exhibit 101 described above. This amendment does not reflect subsequent events occurring after the original filing date of the Form 10-Q or modify or update in any way disclosures made in the Form 10-Q.
Document Period End Date	Jun. 30, 2012