Impairment, Disposition Of Property And Equipment, And Restaurant Closing Costs (Impairment And Disposal Costs Included In Impairment And Other Charges) (Details) (USD $) In Thousands, unless otherwise specified	4 Months Ended
	Jan. 22, 2012	Jan. 23, 2011
Impairment, Disposition Of Property And Equipment, And Restaurant Closing Costs [Abstract]
Impairment charges	$ 1,199	$ 289
Losses on the disposition of property and equipment, net	$ 1,083	$ 2,796
Number of underperforming Jack in the Box restaurants subject to impairment charges	2
Number of Jack in the Box restaurants subject to impairment charges	3