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Employee Retirement Plans - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended	9 Months Ended
	Apr. 30, 2019	Sep. 26, 2020	Sep. 26, 2020	Dec. 28, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Expenses on termination of defined benefit plan			$ 1.1
Pension Benefit Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets at end of fiscal year				$ 3.9
Benefit obligation at end of fiscal year				$ 6.7
Union Number 1199 Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Estimated cost of termination of retirement pension plan	$ 1.1
SAMUnion Number1199 Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Expenses on termination of defined benefit plan		$ 1.5

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Estimated cost of termination of retirement pension plan

+ References

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Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level.

+ References

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-Publisher FASB
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- Definition

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

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Amount of gain (loss) recognized in net periodic benefit (cost) credit from irrevocable action relieving primary responsibility for benefit obligation and eliminating risk related to obligation and assets used to effect settlement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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