CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balance at Dec. 29, 2017	$ 42,936	$ 414	$ 204,920	$ (1,150)	$ (161,248)
Balance (in shares) at Dec. 29, 2017		41,383
Net income	2,413				2,413
Other comprehensive income (loss)	161			161
Common stock issued upon exercise of options	2,405	$ 3	2,402
Common stock issued upon exercise of options (in shares)		306
Stock-based compensation	$ 3,166		3,166
Unvested restricted stock (in shares)	(11)	11
Vested restricted stock	$ 2	$ 2
Vested restricted stock (in shares)		177
Balance at Jun. 29, 2018	51,083	$ 419	210,488	(989)	(158,835)
Balance (in shares) at Jun. 29, 2018		41,877
Balance at Mar. 30, 2018	45,917	$ 416	206,795	(629)	(160,665)
Balance (in shares) at Mar. 30, 2018		41,592
Net income	1,830				1,830
Other comprehensive income (loss)	(360)			(360)
Common stock issued upon exercise of options	1,952	$ 2	1,950
Common stock issued upon exercise of options (in shares)		249
Stock-based compensation	$ 1,743		1,743
Unvested restricted stock (in shares)	(11)	11
Vested restricted stock	$ 1	$ 1
Vested restricted stock (in shares)		25
Balance at Jun. 29, 2018	51,083	$ 419	210,488	(989)	(158,835)
Balance (in shares) at Jun. 29, 2018		41,877
Balance at Dec. 28, 2018	132,426	$ 442	289,584	(1,320)	(156,280)
Balance (in shares) at Dec. 28, 2018		44,195
Net income	5,281				5,281
Adoption of ASC/ ASU | Accounting Standards Update 2016-02	113				113
Adoption of ASC/ ASU | Accounting Standards Update 2018-07			(315)		315
Other comprehensive income (loss)	(282)			(282)
Common stock issued upon exercise of options	$ 1,110	$ 1	1,109
Common stock issued upon exercise of options (in shares)	126	126
Stock-based compensation	$ 5,685		5,685
Unvested restricted stock (in shares)	(11)	11
Vested restricted stock	$ 2	$ 2
Vested restricted stock (in shares)		202
Balance at Jun. 28, 2019	144,335	$ 445	296,063	(1,602)	(150,571)
Balance (in shares) at Jun. 28, 2019		44,534
Balance at Mar. 29, 2019	137,338	$ 444	292,722	(1,343)	(154,485)
Balance (in shares) at Mar. 29, 2019		44,447
Net income	3,914				3,914
Other comprehensive income (loss)	(259)			(259)
Common stock issued upon exercise of options	487	$ 1	486
Common stock issued upon exercise of options (in shares)		52
Stock-based compensation	$ 2,855		2,855
Unvested restricted stock (in shares)	(10)	11
Vested restricted stock (in shares)		24
Balance at Jun. 28, 2019	$ 144,335	$ 445	$ 296,063	$ (1,602)	$ (150,571)
Balance (in shares) at Jun. 28, 2019		44,534