Revenues Disaggregation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 27, 2018	Jun. 28, 2017		Jun. 27, 2018	Jun. 28, 2017
Disaggregation of Revenue [Line Items]
Company restaurant sales	$ 102,741	$ 98,355		$ 203,934	$ 192,134
Franchise and license revenue	54,593	35,021		108,673	69,152
Total operating revenue	157,334	133,376	[1]	312,607	261,286	[1]
Sales Channel, Directly to Consumer [Member]
Disaggregation of Revenue [Line Items]
Company restaurant sales	102,741	98,355	[1]	203,934	192,134	[1]
Sales Channel, Through Intermediary [Member]
Disaggregation of Revenue [Line Items]
Franchise and license revenue	54,593	35,021	[1]	108,673	69,152	[1]
Royalties [Member] | Sales Channel, Through Intermediary [Member]
Disaggregation of Revenue [Line Items]
Franchise and license revenue	25,192	25,338	[1]	50,357	49,882	[1]
Advertising [Member] | Sales Channel, Through Intermediary [Member]
Disaggregation of Revenue [Line Items]
Franchise and license revenue	19,530	0	[1]	38,840	0	[1]
Initial and other fees [Member] | Sales Channel, Through Intermediary [Member]
Disaggregation of Revenue [Line Items]
Franchise and license revenue	1,810	588	[1]	3,227	1,072	[1]
Occupancy [Member] | Sales Channel, Through Intermediary [Member]
Disaggregation of Revenue [Line Items]
Franchise and license revenue	$ 8,061	$ 9,095	[1]	$ 16,249	$ 18,198	[1]

[1] As disclosed in Note 2, prior period amounts have not been adjusted under the modified retrospective method of adoption of Topic 606.