Acquisition (table) (detail) (USD $)	Jun. 29, 2013
Business Acquisition, Cost of Acquired Entity, Purchase Price [Abstract]
Gain Loss On Purchase Of Business During Period	$ 571,000

Change in the amount of the excess of the fair value of acquired net assets over the cost of an acquired business after pro rata reduction of the amounts that otherwise would have been assigned to acquired assets except financial assets other than investments accounted for by the equity method, assets to be disposed of by sale, deferred tax assets, prepaid assets relating to pension and postretirement benefit plans, and other current assets.

No definition available.

Name:	senea_GainLossOnPurchaseOfBusinessDuringPeriod
Namespace Prefix:	senea_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant