Net Income per Share Schedule of earnings per share (Details) - $ / shares	3 Months Ended								12 Months Ended
	Dec. 29, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 30, 2016	Sep. 23, 2016	Jun. 24, 2016	Mar. 25, 2016	Dec. 29, 2017	Dec. 30, 2016	Dec. 25, 2015
Net income per share:
Basic (in dollars per share)	$ 0.36	$ 0.11	$ 0.14	$ (0.06)	$ 0.35	$ 0.05	$ (0.33)	$ 0.04	$ 0.55	$ 0.12	$ 0.63
Diluted (in dollars per share)	$ 0.35	$ 0.11	$ 0.14	$ (0.06)	$ 0.34	$ 0.05	$ (0.33)	$ 0.04	$ 0.54	$ 0.12	$ 0.63
Weighted average common shares:
Weighted average basic common shares outstanding (in shares)									26,118,482	25,919,480	25,532,172
Weighted average diluted common shares outstanding (in shares)									27,424,526	26,029,609	26,508,994