Reconciliations to Statutory Rates (Detail)	12 Months Ended
	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Reconciliation of Statutory Federal Tax Rate [Line Items]
Statutory rate	21.00%	21.00%	35.00%
State income taxes, net of federal benefit	4.60%	4.60%	3.60%
Deduction relating to U.S. production activities			(3.20%)
Deduction relating to excess stock based compensation	(3.20%)	(3.60%)	(3.70%)
Change relating to enacted Tax Cuts and Jobs Act			(17.50%)
Non-deductablemeals & entertainment	0.70%	1.10%	0.90%
Accounting method changes		(3.90%)
Change in valuation allowance	0.40%	0.70%
Other	0.30%	0.40%	(0.40%)
Effective Income Tax Rate Reconciliation, Percent, Total	23.80%	20.30%	14.70%