Document And Entity Information (USD $) In Billions, except Share data, unless otherwise specified	12 Months Ended
	Sep. 28, 2014	Nov. 14, 2014	Apr. 11, 2014
Document And Entity Information [Abstract]
Entity Registrant Name	JACK IN THE BOX INC /NEW/
Entity Central Index Key	0000807882
Document Type	10-K
Document Period End Date	Sep. 28, 2014
Amendment Flag	false
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--09-28
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		38,634,942
Entity Public Float			$ 2.2
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes