Basis Of Presentation (Details)	Jan. 18, 2015 restaurant	Jan. 19, 2014 restaurant
Jack In The Box [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants	2,253	2,254
Qdoba [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants	641	620
Entity Operated Units [Member] | Jack In The Box [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants	431	469
Entity Operated Units [Member] | Qdoba [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants	311	301
Franchised Units [Member] | Jack In The Box [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants	1,822	1,785
Franchised Units [Member] | Qdoba [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants	330	319