SUPPLEMENTAL FINANCIAL STATEMENT DATA - Accrued Liabilities (Details) - USD ($) $ in Thousands	Jul. 03, 2020	Dec. 27, 2019
ACCRUED LIABILITIES
Accrued subcontractor costs	$ 21,502	$ 45,366
Compensation and payroll taxes	5,070	3,286
Accrued bonuses	3,663	7,756
Other	2,506	4,630
Employee withholdings	1,876	3,463
Paid leave bank	1,331	3,114
Total accrued liabilities	$ 35,948	$ 67,615

Carrying value as of the balance sheet date of obligations incurred and payable for incentive compensation awarded to employees and directors or earned by them based on the terms of one or more relevant arrangements. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Carrying value as of the balance sheet date of obligations incurred and payable for unused vacation time owed to employees based on the entity's vacation benefit given to its employees. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Amount of expenses incurred but not yet paid classified as other, due within one year or the normal operating cycle, if longer.

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The aggregate costs related to Accrued Subcontractor Cost and services.

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Represents the carrying value as of the balance sheet date of obligations incurred and payable for statutory payroll taxes incurred through that date and obligations and payables pertaining to compensation to employees.

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The carrying value as of the balance sheet of the withholding of payables of employees.

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