STOCK- BASED COMPENSATION - Performance-based Restricted Stock Units (Details) - Performance-based Restricted Stock Unit $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 26, 2020 USD ($) tradeName $ / shares shares	Dec. 28, 2019 $ / shares shares
Stock Based Compensation
Vesting period of performance-based stock units	3 years
Shares granted \| shares	35,181	31,344
Grants (in dollars per share) \| $ / shares	$ 125.41	$ 136.14
Compensation expense \| $	$ 3,165
Number of plans \| tradeName	2
Minimum
Stock Based Compensation
Performance target (percent)	0.00%
Maximum
Stock Based Compensation
Performance target (percent)	200.00%

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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