CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' DEFICIT (Unaudited) - USD ($) $ in Thousands	Total	Preferred stock	Common stock	Contributed capital	Contributed capital Cumulative effect of accounting changes	Accumulated deficit	Accumulated deficit Cumulative effect of accounting changes	Treasury stock	Accumulated other comprehensive (loss) income
Beginning Balance (in shares) at Dec. 31, 2021		3,955,000
Beginning Balance (in shares) at Dec. 31, 2021			67,649,000
Ending Balance (in shares) at Mar. 31, 2022		3,955,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock awards released and exercise of options (in shares)			154,000
Issuance of common stock under employee purchase plan (in shares)			59,000
Issuance of shares to retire Convertible Senior Notes (in shares)			850,000
Ending Balance (in shares) at Mar. 31, 2022			68,712,000
Beginning Balance, amount at Dec. 31, 2021		$ 4	$ 68	$ 580,652	$ (37,438)	$ (570,668)	$ 25,922	$ (45,067)	$ (60)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee purchase plan				77
Issuance of shares to retire convertible notes			1	1,257
Equity-based compensation				2,833
Net loss	$ (13,465)					(13,465)
Net unrealized gain (loss) on debt securities available-for-sale	(93)								(93)
Foreign currency translation adjustment	(79)								(79)
Ending Balance, amount at Mar. 31, 2022	$ (56,056)	$ 4	$ 69	547,381		(558,211)		(45,067)	(232)
Beginning Balance (in shares) at Dec. 31, 2022	3,954,546	3,955,000
Beginning Balance (in shares) at Dec. 31, 2022	97,477,546		97,478,000
Ending Balance (in shares) at Mar. 31, 2023	3,954,546	3,955,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock awards released and exercise of options (in shares)			2,150,000
Ending Balance (in shares) at Mar. 31, 2023	99,628,248		99,628,000
Beginning Balance, amount at Dec. 31, 2022	$ (22,264)	$ 4	$ 97	630,341		(607,239)		(45,067)	(400)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock awards released			3
Equity-based compensation				562
Net loss	(16,795)					(16,795)
Net unrealized gain (loss) on debt securities available-for-sale	24								24
Foreign currency translation adjustment	(255)								(255)
Ending Balance, amount at Mar. 31, 2023	$ (38,725)	$ 4	$ 100	$ 630,903		$ (624,034)		$ (45,067)	$ (631)