Summary of Refranchisings and Franchise Acquisitions (Summary Of Refranchisings And Franchise Acquisitions) (Details) $ in Thousands	12 Months Ended
Oct. 02, 2022 USD ($) restaurant	Oct. 03, 2021 USD ($) restaurant	Sep. 27, 2020 USD ($) restaurant
Summary Of Refranchisings, Franchisee Development And Acquisitions [Line Items]
Proceeds from the sale of company-operated restaurants	$ 6,391	$ 1,827	$ 3,395
Goodwill related to the sale of company-operated restaurants		(948)
Gains on the sale of company-operated restaurants	$ 30,533	$ 6,888	$ 9,768
Entity Operated Units
Summary Of Refranchisings, Franchisee Development And Acquisitions [Line Items]
Restaurants sold to Jack in the Box franchisees \| restaurant	15	0	0
Proceeds from the sale of company-operated restaurants	$ 6,391	$ 1,827	$ 3,395
Net assets sold (primarily property and equipment)	(1,565)	0	0
Goodwill related to the sale of company-operated restaurants	(948)	0	0
Other	0	2,376	(134)
Gains on the sale of company-operated restaurants	3,878	4,203	3,261
Proceeds from the extension of franchise and lease agreements from the sale of restaurants in prior years	$ 1,400	$ 1,800	$ 3,400

Additional Proceeds From Divestiture Of Businesses And Interests In Affiliates From Prior Years

No definition available.

Name:	jack_AdditionalProceedsFromDivestitureOfBusinessesAndInterestsInAffiliatesFromPriorYears
Namespace Prefix:	jack_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Contingency Adjustments From Divestiture Of Businesses And Interests In Affiliates From Prior Years

+ References

No definition available.

+ Details

Name:	jack_ContingencyAdjustmentsFromDivestitureOfBusinessesAndInterestsInAffiliatesFromPriorYears
Namespace Prefix:	jack_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Summary Of Refranchisings, Franchisee Development And Acquisitions [Line Items].

+ References

No definition available.

+ Details

Name:	jack_SummaryOfRefranchisingsFranchiseeDevelopmentAndAcquisitionsLineItems
Namespace Prefix:	jack_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of gain (loss) on sale or disposal of property, plant and equipment assets, including oil and gas property and timber property.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585

+ Details

Name:	us-gaap_GainLossOnSaleOfPropertyPlantEquipment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of divestiture of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267

+ Details

Name:	us-gaap_GoodwillWrittenOffRelatedToSaleOfBusinessUnit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The cash inflow associated with the amount received from the sale of a business segment or subsidiary or sale of an entity that is related to it but not strictly controlled during the period (for example, an unconsolidated subsidiary, affiliate, joint venture or equity method investment).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3179-108585

+ Details

Name:	us-gaap_ProceedsFromDivestitureOfBusinessesAndInterestsInAffiliates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of divestiture of long-lived, physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentDisposals
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The number of franchises sold during the period when there are significant changes in franchisor-owned outlets or franchised outlets during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 952
-SubTopic 605
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123345378&loc=d3e68639-108044

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 952
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123350991&loc=SL51750552-203207

+ Details

Name:	us-gaap_SignificantChangesFranchisesSold
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_FranchisorDisclosureAxis=us-gaap_EntityOperatedUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: