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Retirement Plans - Narrative (Details)	4 Months Ended
	Jan. 23, 2022 defined_benefit_plan healthcare_plan	Jan. 01, 2021 USD ($)
Retirement Benefits [Abstract]
Number of sponsored defined benefit pension plans | defined_benefit_plan	2
Number of postretirement health care plans | healthcare_plan	2
Minimum required contribution for retirement plans | $		$ 0

X

- Definition

Minimum required contribution for retirement plans

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No definition available.

+ Details

Name:	jack_MinimumRequiredContributionForRetirementPlans
Namespace Prefix:	jack_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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- Definition

Number Of Defined Benefit Pension Plans Sponsored

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No definition available.

+ Details

Name:	jack_NumberOfDefinedBenefitPensionPlansSponsored
Namespace Prefix:	jack_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

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- Definition

Postretirement Medical Plan, Number Sponsored

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No definition available.

+ Details

Name:	jack_PostretirementMedicalPlanNumberSponsored
Namespace Prefix:	jack_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

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- References

No definition available.

+ Details

Name:	us-gaap_CompensationAndRetirementDisclosureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration