Acquisition Pro forma information, 2016 acquisitions (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Jan. 01, 2017	Jan. 03, 2016
2015 Acquisitions [Member]
Business Acquisition [Line Items]
Restaurant sales		$ 918,456
Net income (loss)		$ 6,447
Basic and diluted net income (loss) per share		$ 0.14
2016 Acquisitions [Member]
Business Acquisition [Line Items]
Restaurant sales	$ 984,164	$ 986,935
Net income (loss)	$ 48,264	$ 12,078
Basic and diluted net income (loss) per share	$ 1.07	$ 0.27