Acquisition Table of 2015 Acquisitions (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017 USD ($)	Oct. 01, 2017 USD ($)	Jul. 02, 2017 USD ($)	Apr. 02, 2017 USD ($)	Oct. 02, 2016 USD ($)	Jul. 03, 2016 USD ($)	Apr. 03, 2016 USD ($)	Jan. 03, 2016 USD ($)	Dec. 31, 2017 USD ($)	Jan. 01, 2017 USD ($)	Jan. 03, 2016 USD ($)	Dec. 30, 2012
Business Acquisition [Line Items]
Restaurants Acquired	4		17	43	11	6		27	64	56	55	278
Purchase Price									$ 37,923	$ 48,088	$ 52,750
Properties purchased for sale-leaseback, number										15
Proceeds from sale-leaseback transactions									$ 4,257	$ 53,599	9,148
Land and building								$ 22,614		19,387	$ 22,614
Acquisition-related costs	$ 100	$ 500	$ 500	$ 700	$ 500	$ 200	$ 400	$ 800
2016 Acquisitions [Member]
Business Acquisition [Line Items]
Properties sold in sale-leaseback transactions									14
Proceeds from sale-leaseback transactions									$ 19,100
Revenue of acquired restaurants since acquisition									$ 70,800	28,600
Acquisition-related costs										$ 1,600
2015 Acquisitions [Member]
Business Acquisition [Line Items]
Properties purchased for sale-leaseback, number											16
Properties sold in sale-leaseback transactions								3		12
Proceeds from sale-leaseback transactions								$ 4,300		$ 17,700
Revenue of acquired restaurants since acquisition										$ 70,400	$ 12,900
Acquisition-related costs											$ 200
March 31, 2015 Acquisition [Member]
Business Acquisition [Line Items]
Restaurants Acquired											4
Purchase Price											$ 794
August 4, 2015 Acquisition [Member]
Business Acquisition [Line Items]
Restaurants Acquired											5
Purchase Price											$ 663
October 1, 2015 Acquisition [Member]
Business Acquisition [Line Items]
Restaurants Acquired											5
Purchase Price											$ 5,044
Properties purchased for sale-leaseback, number											1
October 20, 2015 Acquisition [Member]
Business Acquisition [Line Items]
Restaurants Acquired											1
Purchase Price											$ 709
November 17, 2015 Acquisition 1 [Member]
Business Acquisition [Line Items]
Restaurants Acquired											2
Purchase Price											$ 618
November 17, 2015 Acquisition 2 [Member]
Business Acquisition [Line Items]
Restaurants Acquired											6
Purchase Price											$ 10,945
Properties purchased for sale-leaseback, number											5
December 1, 2015 Acquisition [Member]
Business Acquisition [Line Items]
Restaurants Acquired											23
Purchase Price											$ 26,175
Properties purchased for sale-leaseback, number											10
December 8, 2015 Acquisition [Member]
Business Acquisition [Line Items]
Restaurants Acquired											9
Purchase Price											$ 7,802