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]			155,277
Stock plan transactions and other		(235)		$ 1	[1]		(236)
Stock-based compensation expense		1,862					1,862
Net income (loss)		(1,413)						(1,413)
Ending balance (in shares) at Jul. 02, 2019				46,508,586	[1]	2,423,871
Ending balance at Jul. 02, 2019		46,903		$ 465	[1]	$ (35,000)	199,978	(118,540)
Beginning balance (in shares) at Apr. 02, 2019				46,370,951	[1]	2,423,871
Beginning balance at Apr. 02, 2019		45,596		$ 464	[1]	$ (35,000)	199,110	(118,978)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock plan transactions and other (in shares)	[1]			137,635
Stock plan transactions and other		(256)		$ 1	[1]		(257)
Stock-based compensation expense		1,125					1,125
Net income (loss)		438						438
Ending balance (in shares) at Jul. 02, 2019				46,508,586	[1]	2,423,871
Ending balance at Jul. 02, 2019		46,903		$ 465	[1]	$ (35,000)	199,978	(118,540)
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]			220,748
Stock plan transactions and other		(272)		$ 2	[1]		(274)
Stock-based compensation expense		1,290					1,290
Net income (loss)		(19,313)						(19,313)
Ending balance (in shares) at Jun. 30, 2020				46,778,682	[1]	2,423,871
Ending balance at Jun. 30, 2020		32,276		$ 468	[1]	$ (35,000)	201,601	(134,793)
Beginning balance (in shares) at Mar. 31, 2020				46,583,879	[1]	2,423,871
Beginning balance at Mar. 31, 2020		44,906		$ 466	[1]	$ (35,000)	200,755	(121,315)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock plan transactions and other (in shares)	[1]			194,803
Stock plan transactions and other		(271)		$ 2	[1]		(273)
Stock-based compensation expense		1,119					1,119
Net income (loss)		(13,478)						(13,478)
Ending balance (in shares) at Jun. 30, 2020				46,778,682	[1]	2,423,871
Ending balance at Jun. 30, 2020		$ 32,276		$ 468	[1]	$ (35,000)	$ 201,601	$ (134,793)

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