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STOCK BASED COMPENSATION - Assumptions of fair value of stock options (Details)
3 Months Ended 12 Months Ended
Mar. 30, 2019
Dec. 29, 2018
Dec. 30, 2017
Dec. 31, 2016
Assumptions utilized to calculate fair value of stock options granted        
Expected option term 6 years 6 years   6 years
Expected stock price volatility 27.00% 35.00% 30.00%  
Risk-free interest rate 2.50% 2.99%    
Expected stock price volatility, maximum       35.00%
Expected stock price volatility, minimum       30.00%
Risk-free interest rate, minimum     2.05% 1.31%
Risk-free interest rate, maximum     2.18% 1.57%
Expected dividend yield  
Minimum        
Assumptions utilized to calculate fair value of stock options granted        
Expected option term     5 years  
Maximum        
Assumptions utilized to calculate fair value of stock options granted        
Expected option term     6 years