Goodwill (Details) $ in Thousands	12 Months Ended
	Dec. 27, 2020 USD ($)	Dec. 29, 2019 USD ($) restaurant item	Dec. 30, 2018 USD ($)
Goodwill
Goodwill, Beginning Balance	$ 80,340	$ 84,516
Divestitures		(4,435)
Foreign currency adjustments	451	259
Goodwill, Ending Balance	80,791	80,340
Domestic Company-owned Restaurants
Goodwill
Goodwill, Beginning Balance	64,254	68,689
Divestitures		(4,435)
Goodwill, Ending Balance	64,254	$ 64,254
Number of restaurants divested | restaurant		46
Number of domestic markets in which restaurants divested | item		2
International
Goodwill
Goodwill, Beginning Balance	15,650	$ 15,391
Foreign currency adjustments	451	259
Goodwill, Ending Balance	16,101	15,650
Goodwill, accumulated impairment	2,300	2,300	$ 2,300
All others
Goodwill
Goodwill, Beginning Balance	436	436
Goodwill, Ending Balance	$ 436	$ 436