Revenue from Contracts with Customers - Revenues Disaggregated by Revenue Source and Market (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 28, 2022	Sep. 29, 2021	Sep. 28, 2022	Sep. 29, 2021
Disaggregation of Revenue [Line Items]
Total revenue	$ 119,878	$ 115,700	$ 354,037	$ 345,406
Core Market
Disaggregation of Revenue [Line Items]
Total revenue	106,569	102,605	313,365	302,890
Non-Core Market
Disaggregation of Revenue [Line Items]
Total revenue	13,309	13,095	40,672	42,516
Company-operated restaurant revenue
Disaggregation of Revenue [Line Items]
Total revenue	103,174	99,986	303,585	301,117
Company-operated restaurant revenue | Core Market
Disaggregation of Revenue [Line Items]
Total revenue	98,732	95,292	289,798	281,945
Company-operated restaurant revenue | Non-Core Market
Disaggregation of Revenue [Line Items]
Total revenue	4,442	4,694	13,787	19,172
Franchise revenue
Disaggregation of Revenue [Line Items]
Total revenue	9,543	8,918	28,862	24,919
Franchise revenue | Core Market
Disaggregation of Revenue [Line Items]
Total revenue	4,501	4,184	13,559	11,956
Franchise revenue | Non-Core Market
Disaggregation of Revenue [Line Items]
Total revenue	5,042	4,733	15,303	12,963
Franchise advertising fee revenue
Disaggregation of Revenue [Line Items]
Total revenue	7,161	6,796	21,590	19,370
Franchise advertising fee revenue | Core Market
Disaggregation of Revenue [Line Items]
Total revenue	3,336	3,129	10,008	8,989
Franchise advertising fee revenue | Non-Core Market
Disaggregation of Revenue [Line Items]
Total revenue	$ 3,825	$ 3,668	$ 11,582	$ 10,381