v3.10.0.1
BASIS OF PRESENTATION (Details)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2018
USD ($)
state
restaurant
Oct. 01, 2017
Sep. 30, 2018
USD ($)
state
restaurant
Oct. 01, 2017
Jan. 02, 2018
USD ($)
Dec. 31, 2017
USD ($)
Franchisor Disclosure Line Items            
Number Of Restaurants | restaurant 147   147      
Number of States in which Entity Operates | state 33   33      
Effective Income Tax Rate, Continuing Operations 12.30% 37.90% 19.80% 36.90%    
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate     21.00%      
Deferred tax asset $ 6,587   $ 6,587   $ 6,402 $ 5,823
Restricted Cash And Cash Equivalents 1,132   1,132     1,590
Held-to-maturity securities 7,012   7,012      
Accounts receivable, net 3,835   3,835     3,768
Customer Concentration Risk [Member]            
Franchisor Disclosure Line Items            
Accounts receivable, net $ 463   $ 463      
Franchised Units [Member]            
Franchisor Disclosure Line Items            
Number Of Restaurants | restaurant 131   131      
Committed Restaurants | restaurant 63   63      
Entity Operated Units [Member]            
Franchisor Disclosure Line Items            
Number Of Restaurants | restaurant 16   16      
Public Relations and Marketing Development Fund [Member]            
Franchisor Disclosure Line Items            
Restricted Cash And Cash Equivalents $ 1,000   $ 1,000     1,300
Cash Restricted for Letters of Credit [Member]            
Franchisor Disclosure Line Items            
Restricted Cash And Cash Equivalents $ 142   $ 142     $ 298