Reconciliations to Statutory Rates (Detail)	12 Months Ended
Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015
Reconciliation of Statutory Federal Tax Rate [Line Items]
Statutory rate	35.00%	35.00%	35.00%
State income taxes, net of federal benefit	3.60%	3.60%	3.40%
Deduction relating to U.S. production activities	(3.20%)	(2.60%)	(2.70%)
Deduction relating to excess stock benefits	(3.70%)
Change relating to enacted Tax Cuts and Jobs Act	(17.50%)
Change in valuation allowance		(0.30%)
Other	0.50%	0.60%	0.80%
Effective Income Tax Rate Reconciliation, Percent, Total	14.70%	36.30%	36.50%

Reconciliation of Statutory Federal Tax Rate [Line Items]

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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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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Percentage 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 changes in the valuation allowance for deferred tax assets.

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Percentage 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 deduction for dividend paid to employee stock ownership plan.

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Percentage 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 applicable to state and local income tax expense (benefit), net of federal tax expense (benefit).

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