REVENUE FROM CONTRACTS WITH CUSTOMERS - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 28, 2019	Dec. 29, 2018
Revenue from Contract with Customer [Abstract]
Payment terms	30 days
Unpaid advanced client billings	$ 27,000	$ 22,000
Contract liabilities (customer contract deposits)	$ 33,080	$ 38,245
Percentage of unbilled revenue billed during period	95.00%
Percentage of contract liabilities recognized as revenue during period	85.00%