Document And Entity Information	4 Months Ended
	Jan. 20, 2013	Feb. 15, 2013
Document And Entity Information [Abstract]
Entity Registrant Name	JACK IN THE BOX INC /NEW/
Entity Central Index Key	0000807882
Current Fiscal Year End Date	--09-29
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jan. 20, 2013
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		43,520,931