CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Revision of Prior Period, Accounting Standards Update, Adjustment	Common Stock	Additional Paid-in Capital	Additional Paid-in Capital Revision of Prior Period, Accounting Standards Update, Adjustment	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Accumulated Deficit Revision of Prior Period, Accounting Standards Update, Adjustment
Balance at Dec. 28, 2018	$ 132,426		$ 442	$ 289,584		$ (1,320)	$ (156,280)
Balance (Lease Accounting Standard) at Dec. 28, 2018		$ 113						$ 113
Balance (Nonemployee Share-Based Payment Standard) at Dec. 28, 2018					$ (315)			$ 315
Balance (in shares) at Dec. 28, 2018			44,195
Net income	7,669						7,669
Other comprehensive income (loss)	(1,200)					(1,200)
Common stock issued upon exercise of options	1,829		$ 2	1,827
Common stock issued upon exercise of options (in shares)			190
Stock-based compensation	$ 8,501			8,501
Unvested restricted stock (in shares)	(10)		11
Vested restricted stock	$ 2		$ 2
Vested restricted stock (in shares)			210
Balance at Sep. 27, 2019	149,340		$ 446	299,597		(2,520)	(148,183)
Balance (in shares) at Sep. 27, 2019			44,606
Balance at Jun. 28, 2019	144,335		$ 445	296,063		(1,602)	(150,571)
Balance (in shares) at Jun. 28, 2019			44,534
Net income	2,388						2,388
Other comprehensive income (loss)	(918)					(918)
Common stock issued upon exercise of options	719		$ 1	718
Common stock issued upon exercise of options (in shares)			64
Stock-based compensation	$ 2,816			2,816
Unvested restricted stock (in shares)	(10)
Vested restricted stock (in shares)			8
Balance at Sep. 27, 2019	$ 149,340		$ 446	299,597		(2,520)	(148,183)
Balance (in shares) at Sep. 27, 2019			44,606
Balance at Jan. 03, 2020	159,884		$ 448	304,288		(3,048)	(141,804)
Balance (in shares) at Jan. 03, 2020			44,822
Net income	2,586						2,586
Other comprehensive income (loss)	123					123
Common stock issued upon exercise of options	$ 13,986		$ 12	13,974
Common stock issued upon exercise of options (in shares)	1,146		1,146
Stock-based compensation	$ 9,812			9,812
Unvested restricted stock (in shares)	(11)		11
Vested restricted stock	$ 1		$ 1
Vested restricted stock (in shares)			93
Balance at Oct. 02, 2020	186,392		$ 461	328,074		(2,925)	(139,218)
Balance (in shares) at Oct. 02, 2020			46,072
Balance at Jul. 03, 2020	174,674		$ 458	320,235		(2,909)	(143,110)
Balance (in shares) at Jul. 03, 2020			45,788
Net income	3,892						3,892
Other comprehensive income (loss)	(16)					(16)
Common stock issued upon exercise of options	4,429		$ 3	4,426
Common stock issued upon exercise of options (in shares)			269
Stock-based compensation	$ 3,413			3,413
Unvested restricted stock (in shares)	(11)		11
Vested restricted stock (in shares)			4
Balance at Oct. 02, 2020	$ 186,392		$ 461	$ 328,074		$ (2,925)	$ (139,218)
Balance (in shares) at Oct. 02, 2020			46,072