CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Convertible Senior Notes Due 2024	Convertible Senior Notes Due 2026	Convertible Senior Notes Due 2027	Common Stock	Capital in Excess of Par Value	Capital in Excess of Par Value Convertible Senior Notes Due 2024	Capital in Excess of Par Value Convertible Senior Notes Due 2026	Capital in Excess of Par Value Convertible Senior Notes Due 2027	(Accumulated Deficit) Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock
Balance (in shares) at Dec. 31, 2018					17,879,000							1,708,000
Balance at Dec. 31, 2018	$ 45,946				$ 357	$ 50,251				$ 5,427	$ (4,253)	$ (5,836)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of stock options (in shares)					256,000
Issuance of common stock upon the exercise of stock options	1,433				$ 5	1,428
Net issuance of restricted stock awards (in shares)					225,000
Net issuance of restricted stock awards	0				$ 5	(5)
Treasury stock acquired from employees upon exercise of stock options (in shares)												(23,000)
Treasury stock acquired from employees upon exercise of stock options	(544)											$ (544)
Stock-based compensation	2,706					2,706
Issuance of restricted stock for acquisition	27,527					27,527
Payments for common stock issuance costs	0
Proceeds from public share offering, net of issuance costs		$ 12,465					$ 12,465
Foreign currency translation adjustments	(1,115)										(1,115)
Net loss	(15,571)									(15,571)
Balance (in shares) at Dec. 31, 2019					18,360,000							1,731,000
Balance at Dec. 31, 2019	72,847				$ 367	94,372				(10,144)	(5,368)	$ (6,380)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of stock options (in shares)					47,000
Issuance of common stock upon the exercise of stock options	675				$ 1	674
Net issuance of restricted stock awards (in shares)					29,000
Net issuance of restricted stock awards	835				$ 1	834
Treasury stock acquired from employees upon exercise of stock options (in shares)												(57,000)
Treasury stock acquired from employees upon exercise of stock options	(1,186)					(143)						$ (1,043)
Stock-based compensation	4,251					4,251
Net issuance of restricted stock units (in shares)					23,000
Issuance of restricted stock for acquisition (in shares)					908,000
Issuance of restricted stock for acquisition	18				$ 18
Equity component of redeemed 2024 convertible notes (net of deferred taxes of $3.0 million) (in shares)												722,000
Equity component of redeemed 2024 convertible notes (net of deferred taxes of $3.0 million)	(4,372)					(6,808)						$ 2,436
Payments for common stock issuance costs	0		$ 900
Proceeds from public share offering, net of issuance costs (in shares)					3,616,000
Proceeds from public share offering, net of issuance costs	131,407		$ 19,060		$ 72	131,335		$ 19,060
Foreign currency translation adjustments	1,432										1,432
Net loss	$ (36,562)									(36,562)
Balance (in shares) at Dec. 31, 2020	21,917,357				22,983,000							1,066,000
Balance at Dec. 31, 2020	$ 188,405				$ 459	243,575				(46,706)	(3,936)	$ (4,987)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of stock options (in shares)	104,000				105,000
Issuance of common stock upon the exercise of stock options	$ 1,156				$ 2	1,154
Net issuance of restricted stock awards (in shares)					176,000
Net issuance of restricted stock awards	372				$ 4	368
Treasury stock acquired from employees upon exercise of stock options (in shares)												(115,000)
Treasury stock acquired from employees upon exercise of stock options	(5,958)											$ (5,958)
Stock-based compensation	14,615					14,615
Net issuance of restricted stock units (in shares)					2,000
Issuance of restricted stock for acquisition (in shares)					1,493,000
Issuance of restricted stock for acquisition	110,219				$ 30	110,189
Payments for common stock issuance costs	6,828
Proceeds from public share offering, net of issuance costs (in shares)					3,335,000
Proceeds from public share offering, net of issuance costs	208,172			$ 62,931	$ 67	208,105			$ 62,931
Foreign currency translation adjustments	232										232
Net loss	$ (75,799)									(75,799)
Balance (in shares) at Dec. 31, 2021	26,924,397				28,094,000							1,181,000
Balance at Dec. 31, 2021	$ 504,345				$ 562	$ 640,937				$ (122,505)	$ (3,704)	$ (10,945)