Nature Of Operations And Summary Of Significant Accounting Policies (Summary Of Number Of Restaurants) (Details) - restaurant	Oct. 02, 2016	Sep. 27, 2015	Sep. 28, 2014
Jack in the box brand restaurant operations [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of Restaurants	2,255	2,249	2,250
Qdoba brand restaurant operations [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of Restaurants	699	661	638
Company-Operated [Member] | Jack in the box brand restaurant operations [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of Restaurants	417	413	431
Company-Operated [Member] | Qdoba brand restaurant operations [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of Restaurants	367	322	310
Franchise [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	1,836	1,819
Franchise [Member] | Qdoba brand restaurant operations [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of Restaurants	332	339	328