Nature Of Operations And Summary Of Significant Accounting Policies (Summary Of Number Of Restaurants) (Details)	Oct. 02, 2011	Oct. 03, 2010	Sep. 27, 2009
Jack In The Box [Member] | Company-Operated [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants	629	956	1,190
Qdoba [Member] | Company-Operated [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants	245	188	157
Jack In The Box [Member] | Franchise [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants	1,592	1,250	1,022
Qdoba [Member] | Franchise [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants	338	337	353
Jack In The Box [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants	2,221	2,206	2,212
Qdoba [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants	583	525	510