Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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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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The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Stock Plans (Details) - Stock Option Plans - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016
Defined Benefit Plan Disclosure [Line Items]
Shares of common stock available for issuance (in shares)	704,818		704,818
Compensation expense	$ 1,290	$ 1,399	$ 3,868	$ 4,358
Income tax benefits	$ 496	$ 539	$ 1,489	$ 1,678
Minimum
Defined Benefit Plan Disclosure [Line Items]
Vesting period of options			3 years
Expiration period of grant			6 years
Maximum
Defined Benefit Plan Disclosure [Line Items]
Vesting period of options			7 years
Expiration period of grant			10 years