EQUITY-BASED COMPENSATION - Schedule of compensation expense recognized (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 24, 2020	Jun. 26, 2019	Jun. 24, 2020	Jun. 26, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation expense	$ 1,419	$ 2,180	$ 2,719	$ 3,872
Total income tax benefit recognized related to equity-based compensation	39	51	75	93
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation expense	26	655	287	1,337
Performance stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation expense	363	1,007	776	1,719
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation expense	1,030	518	1,656	816
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation expense	1,268	2,084	2,482	3,726
Labor And Related Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation expense	$ 151	$ 96	$ 237	$ 146