Document And Entity Information	9 Months Ended
	Sep. 30, 2011	Nov. 01, 2011
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2011
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	Q3
Entity Filer Category	Accelerated Filer
Entity Registrant Name	SUFFOLK BANCORP
Entity Central Index Key	0000754673
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding		9,726,814