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Nature Of Operations And Summary Of Significant Accounting Policies (Summary Of Number Of Restaurants) (Details) - restaurant	12 Months Ended
	Sep. 30, 2018	Oct. 01, 2017	Oct. 02, 2016
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Document Fiscal Year Focus	2018
Number of Restaurants	10
Jack in the box brand restaurant operations [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of Restaurants	2,237	2,251	2,255
Entity Operated Units [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of Restaurants	137	276
Entity Operated Units [Member] | Jack in the box brand restaurant operations [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of Restaurants			417
Franchised Units [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of Restaurants	2,100	1,975
Franchised Units [Member] | Jack in the box brand restaurant operations [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of Restaurants			1,838

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- Definition

This is focus fiscal year of the document report in CCYY format. For a 2006 annual report, which may also provide financial information from prior periods, fiscal 2006 should be given as the fiscal year focus. Example: 2006.

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Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]

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Represents the number of restaurants.

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