NATURE OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Fair value of financial instruments and Inventories (Details) - item	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017
FAIR VALUE OF FINANCIAL INSTRUMENTS
Number of financial instruments transferred from Level 1 to Level 2	0
Number of financial instruments transferred from Level 2 to Level 1	0
INVENTORIES
Percentage of total LIFO inventory	65.00%	77.00%
Maximum inventory reserve as a percentage of FIFO inventory value	6.80%	1.80%