Supplemental Consolidated Cash Flow Information (Additional Information Related To Cash Flows) (Details) - USD ($) $ in Thousands	6 Months Ended
Apr. 15, 2018	Apr. 16, 2017
Interest, net of amounts capitalized	$ 23,522	$ 18,460
Income tax payments	12,706	27,356
Decrease in obligations for purchases of property and equipment	3,465	1,998
Increase in notes receivable from the sale of company-operated restaurants	31,506	0
Franchise Tenant Improvement Allowances	5,132	1,398
Increase in dividends accrued or converted to common stock equivalents	160	151
Decrease in obligations for treasury stock repurchases	0	(4,466)
Reduction of Equipment Lease Obligation	2,330	2,031
Reduction of Short-term Capital Lease Obligations	233	87
Equipment capital lease obligations incurred	$ 59	$ 59

Franchise Tenant Improvement Allowances

No definition available.

Name:	jack_FranchiseTenantImprovementAllowances
Namespace Prefix:	jack_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Increase (decrease) in dividends accrued or converted to stock equivalents, adjustment to dividends paid, financing activities

+ References

No definition available.

+ Details

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

- Definition

Reduction of Equipment Lease Obligation

+ References

No definition available.

+ Details

Name:	jack_ReductionofEquipmentLeaseObligation
Namespace Prefix:	jack_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The increase during the period in capital lease obligations due to entering into new capital leases.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4313-108586

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586

+ Details

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

- Definition

The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4297-108586

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3536-108585

+ Details

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

- Definition

The increase (decrease) during the reporting period of obligations, not classified as trade payables, incurred and payable for the acquisition of merchandise, materials, supplies, and services pertaining to construction projects.

+ References

No definition available.

+ Details

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

- Definition

The increase (decrease) during the reporting period of the amounts due from borrowers for outstanding secured or unsecured loans evidenced by a note.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

+ Details

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

- Definition

The increase (decrease) during the reporting period in the liability under agreements to repurchase securities that were sold.

+ References

+ Details

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

- Definition

Amount of cash paid, after deduction of cash paid for capitalized interest, for interest. Includes, but is not limited to, payment to settle zero-coupon bond for accreted interest of debt discount and debt instrument with insignificant coupon interest rate in relation to effective interest rate of borrowing attributable to accreted interest of debt discount.

+ References

+ Details

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

- Definition

The cash outflow for a borrowing recorded for a lease meeting the criteria for capitalization (with maturities within one year or the normal operating cycle of the entity, if longer).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

+ Details

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