Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Beginning balance at Dec. 31, 2014	$ 210,400	$ 374	$ 359,465	$ (149,439)
Beginning balance (shares) at Dec. 31, 2014		37,420,450
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock based compensation	539		539
Excess income tax benefit related to share-based compensation plans	4,220	$ 9	4,211
Issuance of common stock upon exercise of stock options (shares)		863,985
Excess income tax benefit related to share-based compensation plans	5,420		5,420
Net income	24,054			24,054
Ending balance at Dec. 30, 2015	244,633	$ 383	369,635	(125,385)
Ending balance (shares) at Dec. 30, 2015		38,284,435
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock based compensation	1,063		1,063
Issuance of common stock related to restricted shares	0
Issuance of common stock related to restricted shares (shares)		41,611
Excess income tax benefit related to share-based compensation plans	$ 978	$ 2	976
Issuance of common stock upon exercise of stock options (shares)	147,726	147,726
Excess income tax benefit related to share-based compensation plans	$ 169		169
Net income	18,339			18,339
Ending balance at Dec. 28, 2016	265,182	$ 385	371,843	(107,046)
Ending balance (shares) at Dec. 28, 2016		38,473,772
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock based compensation	1,056		1,056
Issuance of common stock related to restricted shares	0	$ 2	(2)
Issuance of common stock related to restricted shares (shares)		170,417
Excess income tax benefit related to share-based compensation plans	$ 93		93
Issuance of common stock upon exercise of stock options (shares)	17,661	17,661
Net income	$ 8,619			8,619
Ending balance at Dec. 27, 2017	$ 274,950	$ 387	$ 372,990	$ (98,427)
Ending balance (shares) at Dec. 27, 2017		38,661,850