Acquisition (Details)	3 Months Ended		6 Months Ended		12 Months Ended	15 Months Ended
	Jul. 01, 2018 USD ($)	Jul. 02, 2017 USD ($)	Jul. 01, 2018 USD ($)	Jul. 02, 2017 USD ($)	Dec. 31, 2017 USD ($)	Apr. 01, 2018 USD ($)
Business Acquisition [Line Items]
Right of First Refusal, Number of States	20		20
Number of Restaurants Acquired						65
Business acquisitions, purchase price			$ 0	$ 36,563,000		$ 37,923,000
Proceeds from sale-leaseback transactions			2,862,000	2,717,000
Restaurant sales	$ 303,050,000	$ 279,478,000	$ 574,636,000	$ 519,330,000
November 17, 2015 Acquisition 2 [Member]
Business Acquisition [Line Items]
Number of Restaurants Acquired			1
Business acquisitions, purchase price			$ 0
Franchise rights	290,000		290,000
Liabilities assumed in excess of consideration	230,000		230,000
February 28, 2017 Acquisition [Member]
Business Acquisition [Line Items]
Number of Restaurants Acquired				43
Business acquisitions, purchase price				$ 20,366,000
June 6, 2017 Acquisition [Member]
Business Acquisition [Line Items]
Number of Restaurants Acquired				17
Business acquisitions, purchase price				$ 16,355,000
Acquired Restaurants [Member]
Business Acquisition [Line Items]
Restaurant sales	$ 24,300,000	$ 16,000,000	$ 45,700,000	$ 20,600,000
October 1, 2015 Acquisition [Member]
Business Acquisition [Line Items]
Number of Restaurants Acquired					4
Business acquisitions, purchase price					$ 1,202,000
October 20, 2015 Acquisition [Member]
Business Acquisition [Line Items]
Number of Restaurants Acquired					64
Business acquisitions, purchase price					$ 37,923,000