Changes to Statements of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Treasury Stock [Member]	Total
BALANCES (in shares) at Dec. 31, 2019	36,162				14
BALANCES at Dec. 31, 2019	$ 36	$ 334,299	$ (202,735)	$ (79)	$ (256)	$ 131,265
Exercise of options to purchase common stock (in shares)	408				0
Exercise of options to purchase common stock	$ 1	4,663	0	0	$ 0	4,664
Vesting of restricted stock units (in shares)	75				0
Vesting of restricted stock units	$ 0	(1,636)	0	0	$ 0	(1,636)
Share-based compensation expense	0	7,985	0	0	0	7,985
Foreign Currency Translation	0	0	0	40	0	40
Net income (loss)	$ 0	0	109	0	$ 0	109
Shares issued in primary offering (in shares)	4,000				0
Shares issued in primary offering	$ 4	252,058	0	0	$ 0	252,062
BALANCES (in shares) at Sep. 30, 2020	40,645				14
BALANCES at Sep. 30, 2020	$ 41	597,369	(202,626)	(39)	$ (256)	394,489
BALANCES (in shares) at Jun. 30, 2020	40,480				14
BALANCES at Jun. 30, 2020	$ 40	591,386	(206,173)	(407)	$ (256)	384,591
Exercise of options to purchase common stock (in shares)	164				0
Exercise of options to purchase common stock		2,573	0	0	$ 0	2,573
Vesting of restricted stock units (in shares)	1				0
Vesting of restricted stock units	$ 0	0	0	0	$ 0	0
Share-based compensation expense	0	3,410	0	0	0	3,410
Foreign Currency Translation	0	0	0	368	0	368
Net income (loss)	$ 0	0	3,547	0	$ 0	3,547
BALANCES (in shares) at Sep. 30, 2020	40,645				14
BALANCES at Sep. 30, 2020	$ 41	597,369	(202,626)	(39)	$ (256)	394,489
BALANCES (in shares) at Dec. 31, 2020	40,732				14
BALANCES at Dec. 31, 2020	$ 41	600,388	(205,924)	(80)	$ (256)	394,169
Exercise of options to purchase common stock (in shares)	203				0
Exercise of options to purchase common stock	$ 0	2,048	0	0	$ 0	2,048
Vesting of restricted stock units (in shares)	54				0
Vesting of restricted stock units	$ 0	(3,198)	0	0	$ 0	(3,198)
Share-based compensation expense	0	18,587	0	0	0	18,587
Foreign Currency Translation	0	0	0	173	0	173
Net income (loss)	$ 0	0	(20,433)	0	$ 0	(20,433)
Shares issued in primary offering (in shares)	2,415				0
Shares issued in primary offering	$ 2	332,170	0	0	$ 0	332,172
BALANCES (in shares) at Sep. 30, 2021	43,404				14
BALANCES at Sep. 30, 2021	$ 43	949,995	(226,357)	93	$ (256)	723,518
BALANCES (in shares) at Jun. 30, 2021	43,373				14
BALANCES at Jun. 30, 2021	$ 43	944,222	(224,287)	89	$ (256)	719,811
Exercise of options to purchase common stock (in shares)	29				0
Exercise of options to purchase common stock	$ 0	308	0	0	$ 0	308
Vesting of restricted stock units (in shares)	2				0
Vesting of restricted stock units	$ 0	(281)	0	0	$ 0	(281)
Share-based compensation expense	0	5,746	0	0	0	5,746
Foreign Currency Translation	0	0	0	4	0	4
Net income (loss)	$ 0	0	(2,070)	0	$ 0	(2,070)
BALANCES (in shares) at Sep. 30, 2021	43,404				14
BALANCES at Sep. 30, 2021	$ 43	$ 949,995	$ (226,357)	$ 93	$ (256)	$ 723,518