Reconciliations to Statutory Rates (Detail)	12 Months Ended
Dec. 26, 2020	Dec. 28, 2019	Dec. 29, 2018
Income Tax Disclosure [Abstract]
Statutory rate	21.00%	21.00%	21.00%
State income taxes, net of federal benefit	4.40%	4.60%	4.60%
Deduction relating to excess stock based compensation	(4.30%)	(3.20%)	(3.60%)
Non-deductable meals & entertainment	0.20%	0.70%	1.10%
Accounting method changes			(3.90%)
Change in valuation allowance	0.10%	0.40%	0.70%
Other		0.30%	0.40%
Effective Income Tax Rate Reconciliation, Percent, Total	21.40%	23.80%	20.30%

Effective income tax rate reconciliation change in accounting method.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
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-Subparagraph (SAB Topic 6.I.Fact.4)
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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.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
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- Definition

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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