Condensed Consolidated Statements Of Earnings (USD $) In Thousands, except Per Share data, unless otherwise specified	4 Months Ended
Jan. 18, 2015	Jan. 19, 2014
Common Stock, Dividends, Per Share, Cash Paid	$ 0.20	$ 0.00
Revenues:
Company restaurant sales	$ 351,896us-gaap_SalesRevenueGoodsNet	$ 338,828us-gaap_SalesRevenueGoodsNet
Franchise revenues	116,725us-gaap_FranchiseRevenue	111,253us-gaap_FranchiseRevenue
Total revenue	468,621us-gaap_Revenues	450,081us-gaap_Revenues
Company restaurant costs:
Food and packaging	113,109us-gaap_CostOfGoodsSoldDirectMaterials	108,238us-gaap_CostOfGoodsSoldDirectMaterials
Payroll and employee benefits	95,679us-gaap_CostOfGoodsSoldDirectLabor	93,816us-gaap_CostOfGoodsSoldDirectLabor
Occupancy and other	75,031us-gaap_CostOfGoodsSoldOverhead	74,709us-gaap_CostOfGoodsSoldOverhead
Total company restaurant costs	283,819us-gaap_CostOfGoodsSold	276,763us-gaap_CostOfGoodsSold
Franchise costs	57,141us-gaap_FranchiseCosts	55,510us-gaap_FranchiseCosts
Selling, general and administrative expenses	63,095	59,156
Impairment and other charges, net	2,180jack_ImpairmentAndOtherCostsNet	1,909jack_ImpairmentAndOtherCostsNet
Gains on the sale of company-operated restaurants	(850)	(461)
Total operating costs and expenses	405,385us-gaap_CostsAndExpenses	392,877us-gaap_CostsAndExpenses
Earnings from operations	63,236us-gaap_OperatingIncomeLoss	57,204us-gaap_OperatingIncomeLoss
Interest expense, net	5,213us-gaap_InterestIncomeExpenseNet	4,542us-gaap_InterestIncomeExpenseNet
Earnings from continuing operations and before income taxes	58,023	52,662
Income taxes	20,925us-gaap_IncomeTaxExpenseBenefit	19,652us-gaap_IncomeTaxExpenseBenefit
Earnings from continuing operations	37,098	33,010
Losses from discontinued operations, net of income tax benefit	(1,263)	(724)
Net earnings	$ 35,835us-gaap_NetIncomeLoss	$ 32,286us-gaap_NetIncomeLoss
Net earnings per share - basic:
Earnings from continuing operations (usd per share)	$ 0.96	$ 0.78
Losses from discontinued operations (usd per share)	$ (0.03)	$ (0.02)
Net earnings per share (usd per share)	$ 0.93us-gaap_EarningsPerShareBasic	$ 0.76us-gaap_EarningsPerShareBasic
Net earnings per share - diluted:
Earnings from continuing operations (usd per share)	$ 0.94	$ 0.75
Losses from discontinued operations (usd per share)	$ (0.03)	$ (0.02)
Net earnings per share (usd per share)	$ 0.91us-gaap_EarningsPerShareDiluted	$ 0.74us-gaap_EarningsPerShareDiluted
Weighted-average shares outstanding:
Basic (in shares)	38,640	42,434
Diluted (in shares)	39,384	43,838

Includes the charge against earnings resulting from the aggregate of write down of assets from their carrying value to their fair value, lease reserves established when we cease using a property under an operating lease and subsequent adjustments to those reserves and other facility-related expenses from previously closed stores, as well as the net gain or loss on sales of real estate on which we formerly operated a Company restaurant that was closed. Also included within this balance are restructuring costs.

No definition available.