Basis Of Presentation (Details) $ in Millions	4 Months Ended
Jan. 23, 2022 USD ($) restaurant segment	Jan. 17, 2021 USD ($) restaurant
Segment Reporting Information [Line Items]
Number of restaurants	2,208	2,237
Number of operating segments \| segment	1
Contractual obligation (percent)	5.00%
Marketing and advertising expense \| $	$ 6.1	$ 5.8
Entity Operated Units
Segment Reporting Information [Line Items]
Number of restaurants	165	148
Franchised Units
Segment Reporting Information [Line Items]
Number of restaurants	2,043	2,089

ContractualContributionsTowardsAdvertisingCostsPercentageOfSales [Line Items]

No definition available.

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Namespace Prefix:	jack_
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- Definition

The total expense recognized in the period for promotion, public relations, and brand or product advertising.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.4)
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

+ Details

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Period Type:	duration

- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8672-108599

+ Details

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Period Type:	duration

- Definition

Represents the number of restaurants.

+ References

No definition available.

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Details

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