Document and Entity Information - shares	6 Months Ended
	Sep. 26, 2015	Oct. 23, 2015
Document And Entity Information [Abstract]
Document Type	10-Q
Document period end date	Sep. 26, 2015
Amendment flag	false
Document Period Focus	Q2
Document Fiscal Year Focus	2016
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		7,922,246
Trading Symbol	SENEA
Common Class B Member
Class Of Stock [Line Items]
Entity common stock shares outstanding		1,967,858
Trading Symbol	SENEB