Document and Entity Information	9 Months Ended
	Dec. 27, 2014	Jan. 23, 2015
Document And Entity Information [Abstract]
Document Type	10-Q
Document period end date	Dec. 27, 2014
Amendment flag	false
Document Period Focus	Q3
Document Fiscal Year Focus	2015
Current fiscal year end date	--03-31
Entity central index key	0000088948
Entity current reporting status	Yes
Entity filer category	Accelerated Filer
Entity registrant name	SENECA FOODS CORP /NY/
Entity voluntary filers	No
Entity well known seasoned issuer	No
Common Class A Member
Class Of Stock [Line Items]
Entity common stock shares outstanding		8,717,440
Trading Symbol	SENEA
Common Class B Member
Class Of Stock [Line Items]
Entity common stock shares outstanding		2,015,673
Trading Symbol	SENEB