Impairment of Long-Lived Assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Oct. 01, 2017	Sep. 30, 2018	Oct. 01, 2017
Impaired Long-Lived Assets Held and Used
Impairment of long-lived assets	$ 347	$ 1,041	$ 2,156	$ 1,804
Restaurants leased or subleased to franchisees
Impaired Long-Lived Assets Held and Used
Impairment of long-lived assets	118	95	283	95
Company-operated restaurants
Impaired Long-Lived Assets Held and Used
Impairment of long-lived assets	0	833	1,603	1,051
Surplus Properties
Impaired Long-Lived Assets Held and Used
Impairment of long-lived assets	$ 229	$ 113	$ 270	$ 658