REVENUE FROM CONTRACTS WITH CUSTOMERS - Revenues Disaggregated by Revenue Source and Market (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 27, 2023	Dec. 28, 2022	Dec. 29, 2021
Disaggregation of Revenue [Line Items]
Total revenue	$ 468,664	$ 469,959	$ 454,363
Core Market
Disaggregation of Revenue [Line Items]
Total revenue	414,644	415,680	399,146
Non-Core Market
Disaggregation of Revenue [Line Items]
Total revenue	54,020	54,279	55,217
Company-operated restaurant revenue
Disaggregation of Revenue [Line Items]
Total revenue	398,437	403,218	394,733
Company-operated restaurant revenue | Core Market
Disaggregation of Revenue [Line Items]
Total revenue	381,319	384,504	371,067
Company-operated restaurant revenue | Non-Core Market
Disaggregation of Revenue [Line Items]
Total revenue	17,118	18,714	23,666
Franchise revenue
Disaggregation of Revenue [Line Items]
Total revenue	41,002	38,225	33,729
Franchise revenue | Core Market
Disaggregation of Revenue [Line Items]
Total revenue	19,805	17,953	16,062
Franchise revenue | Non-Core Market
Disaggregation of Revenue [Line Items]
Total revenue	21,197	20,272	17,667
Franchise advertising fee revenue
Disaggregation of Revenue [Line Items]
Total revenue	29,225	28,516	25,901
Franchise advertising fee revenue | Core Market
Disaggregation of Revenue [Line Items]
Total revenue	13,520	13,223	12,017
Franchise advertising fee revenue | Non-Core Market
Disaggregation of Revenue [Line Items]
Total revenue	$ 15,705	$ 15,293	$ 13,884