Company's Effective Tax Rate Differs From Statutory Federal Tax Rate (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Jan. 02, 2015	Jan. 03, 2014	Dec. 28, 2012
Schedule Of Company Effective Tax Rate Differs From Statutory Federal Tax Rate [Line Items]
Tax at federal statutory rate	$ 23,788	$ 22,381	$ 21,612
State taxes, net of federal benefit	3,226	2,819	2,409
Tax exempt interest income	(44)	(36)	(104)
Non-deductible expenses	289	226	296
Non-deductible stock-based compensation	0	(79)	(40)
Other	5	(6)	351
Tax expense	$ 27,264us-gaap_IncomeTaxExpenseBenefit	$ 25,305us-gaap_IncomeTaxExpenseBenefit	$ 24,524us-gaap_IncomeTaxExpenseBenefit
Effective tax rate	40.10%	39.60%	39.70%

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to nondeductible expenses.

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