Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands		Total	Adoption of ASU No. 2016-02 Leases	Common Stock		Treasury Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Deficit Adoption of ASU No. 2016-02 Leases
Beginning balance (in shares) at Jan. 01, 2019				46,353,309	[1]	2,423,871
Beginning balance at Jan. 01, 2019		$ 52,681	$ (5,992)	$ 464	[1]	$ (35,000)	$ 198,352	$ (111,135)	$ (5,992)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock plan transactions and other (in shares)	[1]			192,683
Stock plan transactions and other		(284)		$ 1	[1]		(285)
Stock-based compensation expense		1,811					1,811
Net income (loss)		2,830						2,830
Ending balance (in shares) at Oct. 01, 2019				46,545,992	[1]	2,423,871
Ending balance at Oct. 01, 2019		51,046		$ 465	[1]	$ (35,000)	199,878	(114,297)
Beginning balance (in shares) at Jul. 02, 2019				46,508,586		2,423,871
Beginning balance at Jul. 02, 2019		46,903		$ 465		$ (35,000)	199,978	(118,540)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock plan transactions and other (in shares)				37,406
Stock plan transactions and other		(49)		$ 0			(49)
Stock-based compensation expense		(51)					(51)
Net income (loss)		4,243						4,243
Ending balance (in shares) at Oct. 01, 2019				46,545,992	[1]	2,423,871
Ending balance at Oct. 01, 2019		51,046		$ 465	[1]	$ (35,000)	199,878	(114,297)
Beginning balance (in shares) at Dec. 31, 2019				46,557,934	[1]	2,423,871
Beginning balance at Dec. 31, 2019		50,571		$ 466	[1]	$ (35,000)	200,585	(115,480)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock plan transactions and other (in shares)	[1]			237,600
Stock plan transactions and other		(223)		$ 2	[1]		(225)
Stock-based compensation expense		1,954					1,954
Net income (loss)		(19,440)						(19,440)
Ending balance (in shares) at Sep. 29, 2020				46,795,534	[1]	2,423,871
Ending balance at Sep. 29, 2020		32,862		$ 468	[1]	$ (35,000)	202,314	(134,920)
Beginning balance (in shares) at Jun. 30, 2020				46,778,682		2,423,871
Beginning balance at Jun. 30, 2020		32,276		$ 468		$ (35,000)	201,601	(134,793)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock plan transactions and other (in shares)				16,852
Stock plan transactions and other		49		$ 0			49
Stock-based compensation expense		664					664
Net income (loss)		(127)						(127)
Ending balance (in shares) at Sep. 29, 2020				46,795,534	[1]	2,423,871
Ending balance at Sep. 29, 2020		$ 32,862		$ 468	[1]	$ (35,000)	$ 202,314	$ (134,920)

[1] Unless otherwise noted, activity relates to Class A common stock.