System Optimization (Gains) Losses, Net Summary of Disposition Activity (Details) $ in Thousands		3 Months Ended		9 Months Ended
	May 31, 2017 USD ($) number_of_restaurants	Sep. 30, 2018 USD ($)	Oct. 01, 2017 USD ($)	Sep. 30, 2018 USD ($) number_of_restaurants	Oct. 01, 2017 USD ($) number_of_restaurants
System optimization gains (losses), net
Company-operated restaurant ownership percentage		5.00%		5.00%
System optimization gains (losses), net		$ 486	$ (106)	$ 8	$ (39,749)
Proceeds from sales				$ 2,863	80,058
Sale of Company-operated restaurants to franchisees
System optimization gains (losses), net
Number of restaurants sold to franchisees | number_of_restaurants				3
System optimization gains (losses), net		0	0	$ 89	0
Post closing adjustments on sales of restaurants		279	418	54	1,345
Proceeds from sales				1,436
Net Assets Sold				(1,139)
Goodwill				(208)
Cash proceeds from post closing adjustments, net of payments				6
Cash payments for post closing adjustments, net of proceeds			333		33
Recognition of deferred gain on sale of property		503		$ 503	$ 312
Sale of franchise-operated restaurant to franchisee
System optimization gains (losses), net
Number of restaurants sold to franchisees | number_of_restaurants				73	270
Sale of Other Assets
System optimization gains (losses), net
System optimization gains (losses), net		207	(539)	$ (135)	$ 2,040
Proceeds from sales		1,049	2,411	1,421	9,403
Recognition of deferred gain on sale of property					375
NPC Disposition
System optimization gains (losses), net
Number of restaurants sold to franchisees | number_of_restaurants	140
System optimization gains (losses), net		$ 0	15	0	(43,134)
Proceeds from sales	$ 70,688
Goodwill					(65,476)
Selling and other costs			(12)		(1,692)
Net favorable leases					$ 24,034
DavCo Acquisition
System optimization gains (losses), net
Goodwill			$ (27)
Restaurants acquired from franchisees | number_of_restaurants	140
Total consideration paid, net of cash received	$ 86,788
Supplemental purchase price				$ 6,269