Document And Entity Information - shares	9 Months Ended
	Jul. 05, 2015	Jul. 31, 2015
Entity Information [Line Items]
Entity Registrant Name	JACK IN THE BOX INC /NEW/
Entity Central Index Key	0000807882
Current Fiscal Year End Date	--09-27
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jul. 05, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		36,577,272