Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]
Beginning balance, value at Dec. 25, 2013	$ 48,536	$ 287	$ 240,151	$ (191,902)
Beginning balance, shares at Dec. 25, 2013		28,712,622
Stock based compensation	1,093		1,093
Issuance of common stock for initial public offering, net of offering costs of $10,914	112,300	$ 82	112,218
Issuance of common stock for initial public offering, net of offering costs of $10,914, shares		8,214,286
Issuance of common stock upon exercise of stock options, value	2,043	$ 5	2,038
Issuance of common stock upon exercise of stock options, shares		493,542
Excess income tax benefit related to share-based compensation plans	3,965		3,965
Net income	42,463			42,463
Ending balance, value at Dec. 31, 2014	210,400	$ 374	359,465	(149,439)
Ending balance, shares at Dec. 31, 2014		37,420,450
Stock based compensation	539		539
Issuance of common stock upon exercise of stock options, value	$ 4,220	$ 9	4,211
Issuance of common stock upon exercise of stock options, shares	863,247	863,985
Excess income tax benefit related to share-based compensation plans	$ 5,420		5,420
Net income	24,054			24,054
Ending balance, value at Dec. 30, 2015	244,633	$ 383	369,635	(125,385)
Ending balance, shares at Dec. 30, 2015		38,284,435
Stock based compensation	1,063		1,063
Issuance of common stock related to restricted shares, shares		41,611
Issuance of common stock upon exercise of stock options, value	$ 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, value at Dec. 28, 2016	$ 265,182	$ 385	$ 371,843	$ (107,046)
Ending balance, shares at Dec. 28, 2016		38,473,772