Note 10 (Details) - Intangible Assets by Reporting Segment (USD $) In Thousands, unless otherwise specified	Mar. 28, 2015	Sep. 27, 2014
Amortized intangible assets
Accumulated Amortization	$ 42,722	$ 40,015
Gross Carrying Amount	91,004	91,004
Trade Names [Member] \| Food Service [Member]
Indefinite lived intangible assets
Gross Carrying Amount	13,072	13,072
Trade Names [Member] \| Retail Supermarket [Member]
Indefinite lived intangible assets
Gross Carrying Amount	7,206	7,206
Trade Names [Member] \| Frozen Beverages [Member]
Indefinite lived intangible assets
Gross Carrying Amount	9,315	9,315
Food Service [Member] \| Noncompete Agreements [Member]
Amortized intangible assets
Gross Carrying Amount	592	592
Accumulated Amortization	525	509
Food Service [Member] \| Customer Relationships [Member]
Amortized intangible assets
Gross Carrying Amount	40,797	40,797
Accumulated Amortization	31,775	29,914
Food Service [Member] \| License and Rights [Member]
Amortized intangible assets
Gross Carrying Amount	3,606	3,606
Accumulated Amortization	2,755	2,708
Food Service [Member]
Amortized intangible assets
Accumulated Amortization	35,055	33,131
Gross Carrying Amount	58,067	58,067
Retail Supermarket [Member] \| Noncompete Agreements [Member]
Amortized intangible assets
Gross Carrying Amount	160	160
Accumulated Amortization	73	34
Retail Supermarket [Member] \| Customer Relationships [Member]
Amortized intangible assets
Gross Carrying Amount	7,979	7,979
Accumulated Amortization	820	420
Retail Supermarket [Member]
Amortized intangible assets
Accumulated Amortization	893	454
Gross Carrying Amount	15,345	15,345
Frozen Beverages [Member] \| Noncompete Agreements [Member]
Amortized intangible assets
Gross Carrying Amount	198	198
Accumulated Amortization	198	198
Frozen Beverages [Member] \| Customer Relationships [Member]
Amortized intangible assets
Gross Carrying Amount	6,478	6,478
Accumulated Amortization	5,757	5,448
Frozen Beverages [Member] \| License and Rights [Member]
Amortized intangible assets
Gross Carrying Amount	1,601	1,601
Accumulated Amortization	819	784
Frozen Beverages [Member]
Amortized intangible assets
Accumulated Amortization	6,774	6,430
Gross Carrying Amount	$ 17,592	$ 17,592

Name:	jjsf_AmortizedIntangibleAssetsAbstract
Namespace Prefix:	jjsf_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Name:	jjsf_IndefiniteLivedIntangibleAssetsAbstract
Namespace Prefix:	jjsf_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount (original costs adjusted for previously recognized amortization and impairment) as of the balance sheet date for the rights acquired through registration of a trade name to gain or protect exclusive use thereof for a projected indefinite period of benefit.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

+ Details

Name:	us-gaap_IndefiniteLivedTradeNames
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount before accumulated amortization of intangible assets, excluding goodwill.

+ References

No definition available.

+ Details

Name:	us-gaap_IntangibleAssetsGrossExcludingGoodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_TradeNamesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=jjsf_FoodServiceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=jjsf_FrozenBeveragesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=jjsf_RetailSupermarketMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: