REVENUE FROM CONTRACTS WITH CUSTOMERS - Revenues Disaggregated by Revenue Source and Market (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 28, 2022	Dec. 29, 2021	Dec. 30, 2020
Disaggregation of Revenue [Line Items]
Total revenue	$ 469,959	$ 454,363	$ 426,087
Core Market
Disaggregation of Revenue [Line Items]
Total revenue	415,680	399,146	371,510
Non-Core Market
Disaggregation of Revenue [Line Items]
Total revenue	54,279	55,217	54,577
Company-operated restaurant revenue
Disaggregation of Revenue [Line Items]
Total revenue	403,218	394,733	374,064
Company-operated restaurant revenue | Core Market
Disaggregation of Revenue [Line Items]
Total revenue	384,504	371,067	346,662
Company-operated restaurant revenue | Non-Core Market
Disaggregation of Revenue [Line Items]
Total revenue	18,714	23,666	27,402
Franchise revenue
Disaggregation of Revenue [Line Items]
Total revenue	38,225	33,729	29,418
Franchise revenue | Core Market
Disaggregation of Revenue [Line Items]
Total revenue	17,953	16,062	14,216
Franchise revenue | Non-Core Market
Disaggregation of Revenue [Line Items]
Total revenue	20,272	17,667	15,202
Franchise advertising fee revenue
Disaggregation of Revenue [Line Items]
Total revenue	28,516	25,901	22,605
Franchise advertising fee revenue | Core Market
Disaggregation of Revenue [Line Items]
Total revenue	13,223	12,017	10,632
Franchise advertising fee revenue | Non-Core Market
Disaggregation of Revenue [Line Items]
Total revenue	$ 15,293	$ 13,884	$ 11,973