Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]	Total
Beginning Balance at Dec. 31, 2019	$ 548	$ (53)	$ 489,925	$ 20	$ (183,143)	$ 307,297
Beginning Balance (in shares) at Dec. 31, 2019	54,773,061
Issuance of common stock pursuant to exercise of stock options	$ 3	0	(3)	0	0	0
Issuance of common stock pursuant to exercise of stock options (in shares)	386,974
Share repurchase	$ 0	0	(72)	0	0	(72)
Share repurchase (in shares)	(3,000)
Sale of treasury stock	$ 0	53	0	0	0	53
Sale of treasury stock (in shares)	0
Issuance of treasury stock pursuant to exercise of stock options	$ 0	(429)	0	0	0	(429)
Issuance of treasury stock pursuant to exercise of stock options (in shares)	0
Unrealized comprehensive loss on investments	$ 0	0	0	(95)	0	(95)
Share-based compensation	0	0	3,961	0	0	3,961
Net loss	0	0	0	0	(24,664)	(24,664)
Ending Balance at Mar. 31, 2020	$ 551	(429)	493,811	(75)	(207,807)	286,051
Ending Balance (in shares) at Mar. 31, 2020	55,157,035
Beginning Balance at Dec. 31, 2020	$ 610	0	825,794	(42)	(322,843)	503,519
Beginning Balance (in shares) at Dec. 31, 2020	60,996,367
Issuance of common stock pursuant to exercise of stock options	$ 9	0	8,783	0	0	8,792
Issuance of common stock pursuant to exercise of stock options (in shares)	991,432
Unrealized comprehensive loss on investments	$ 0	0	0	(33)	0	(33)
Share-based compensation	0	0	7,900	0	0	7,900
Net loss	0	0	0	0	(40,179)	(40,179)
Ending Balance at Mar. 31, 2021	$ 619	$ 0	$ 842,477	$ (75)	$ (363,022)	$ 479,999
Ending Balance (in shares) at Mar. 31, 2021	61,987,799