SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Restaurant Revenue and Advertising Costs (Details) $ in Thousands	12 Months Ended
	Dec. 27, 2023 USD ($) restaurant	Dec. 28, 2022 USD ($)	Dec. 29, 2021 USD ($)
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Promotional allowances amount	$ 8,700	$ 7,500	$ 7,700
Loyalty Rewards Program, Expiration Period For Inactivity	1 year
Accrued Loyalty Rewards Program Liability, Current	$ 700	500
Loyalty Rewards Program, Expected Loyalty Points Redemption Period	1 year
Number of franchised restaurants committed to open | restaurant	107
Advertising expense	$ 16,200	16,400	16,100
Accrued advertising	3,010	831
Accrued advertising obligated to spend in future	$ 3,000
Initial lease term	20 years
Minimum
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	10 years
Percentage of monthly franchise fee	4.00%
Maximum
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	20 years
Percentage of monthly franchise fee	5.00%
Hardware Services
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Unsatisfied performance obligations	$ 0
Franchise Rights
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Renewal period	20 years
Franchise agreement term	20 years
General and Administrative Expense
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Preopening costs	$ 300	300	300
Franchised
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Advertising fees	$ 29,200	$ 28,500	$ 25,900