CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Convertible Senior Notes due 2024 Convertible Notes	Convertible Senior Notes Due 2026 Convertible Notes	Convertible Senior Notes Due 2027	Convertible Senior Notes Due 2027 Convertible Notes	Common Stock	Common Stock Convertible Senior Notes Due 2027	Additional Paid in Capital	Additional Paid in Capital Convertible Senior Notes due 2024 Convertible Notes	Additional Paid in Capital Convertible Senior Notes Due 2026 Convertible Notes	Additional Paid in Capital Convertible Senior Notes Due 2027	Accumulated Deficit	Accumulated Other Comprehensive Loss	Treasury Stock	Treasury Stock Convertible Senior Notes due 2024 Convertible Notes
Beginning Balance (in shares) at Dec. 31, 2019						18,360,000								1,731,000
Beginning 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)						2,000
Issuance of common stock upon the exercise of stock options	30							30
Net issuance of restricted stock awards (in shares)						21,000
Treasury stock acquired from employees upon vesting or forfeiture of restricted stock (in shares)														38,000
Treasury stock acquired from employees upon vesting or forfeiture of restricted stock	(524)													$ (524)
Issuance of restricted stock for acquisition (in shares)						908,000
Issuance of restricted stock for acquisition	19					$ 19
Issuance of common stock (in shares)															(722,000)
Issuance of common stock		$ (5,553)	$ 19,097						$ (7,988)	$ 19,097					$ 2,435
Stock-based compensation	1,089							1,089
Foreign currency translation adjustments	201												201
Net loss	(10,910)											(10,910)
Ending Balance (in shares) at Mar. 31, 2020						19,291,000								1,047,000
Ending Balance at Mar. 31, 2020	76,296					$ 386		106,600				(21,054)	(5,167)	$ (4,469)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Convertible notes conversion discount, taxes		$ 1,800	6,200		$ 600
Beginning Balance (in shares) at Dec. 31, 2019						18,360,000								1,731,000
Beginning Balance at Dec. 31, 2019	72,847					$ 367		94,372				(10,144)	(5,368)	$ (6,380)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Foreign currency translation adjustments	309
Net loss	(23,597)
Ending Balance (in shares) at Sep. 30, 2020						19,315,000								1,052,000
Ending Balance at Sep. 30, 2020	66,775					$ 386		109,772				(33,741)	(5,059)	$ (4,583)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Convertible notes conversion discount, taxes			$ (4,400)		$ (15,900)
Beginning Balance (in shares) at Mar. 31, 2020						19,291,000								1,047,000
Beginning Balance at Mar. 31, 2020	76,296					$ 386		106,600				(21,054)	(5,167)	$ (4,469)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of stock options (in shares)						4,000
Issuance of common stock upon the exercise of stock options	12							12
Treasury stock acquired from employees upon vesting or forfeiture of restricted stock (in shares)														3,000
Treasury stock acquired from employees upon vesting or forfeiture of restricted stock	(3)							(195)						$ 192
Stock-based compensation	1,123							1,123
Foreign currency translation adjustments	158												158
Net loss	(8,976)											(8,976)
Ending Balance (in shares) at Jun. 30, 2020						19,295,000								1,050,000
Ending Balance at Jun. 30, 2020	68,610					$ 386		107,540				(30,030)	(5,009)	$ (4,277)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of stock options (in shares)						20,000
Issuance of common stock upon the exercise of stock options	394							394
Net issuance of restricted stock awards	833							833
Treasury stock acquired from employees upon vesting or forfeiture of restricted stock (in shares)														2,000
Treasury stock acquired from employees upon vesting or forfeiture of restricted stock	(306)													$ (306)
Stock-based compensation	1,005							1,005
Foreign currency translation adjustments	(50)												(50)
Net loss	(3,711)											(3,711)
Ending Balance (in shares) at Sep. 30, 2020						19,315,000								1,052,000
Ending Balance at Sep. 30, 2020	$ 66,775					$ 386		109,772				(33,741)	(5,059)	$ (4,583)
Beginning Balance (in shares) at Dec. 31, 2020	21,917,357					22,983,000								1,066,000
Beginning 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)						34,000
Issuance of common stock upon the exercise of stock options	409					$ 1		408
Net issuance of restricted stock awards (in shares)						87,000
Net issuance of restricted stock awards	265					$ 2		263
Treasury stock acquired from employees upon vesting or forfeiture of restricted stock (in shares)														76,000
Treasury stock acquired from employees upon vesting or forfeiture of restricted stock	(3,974)													$ (3,974)
Stock-based compensation	1,320							1,320
Foreign currency translation adjustments	(302)												(302)
Net loss	(8,271)											(8,271)
Ending Balance (in shares) at Mar. 31, 2021						23,104,000								1,142,000
Ending Balance at Mar. 31, 2021	$ 177,852					$ 462		245,566				(54,977)	(4,238)	$ (8,961)
Beginning Balance (in shares) at Dec. 31, 2020	21,917,357					22,983,000								1,066,000
Beginning 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)	76,000
Foreign currency translation adjustments	$ (56)
Net loss	$ (50,160)
Ending Balance (in shares) at Sep. 30, 2021	26,855,578					28,017,000								1,161,000
Ending Balance at Sep. 30, 2021	$ 524,681					$ 560		634,895				(96,866)	(3,992)	$ (9,916)
Beginning Balance (in shares) at Mar. 31, 2021						23,104,000								1,142,000
Beginning Balance at Mar. 31, 2021	177,852					$ 462		245,566				(54,977)	(4,238)	$ (8,961)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of stock options (in shares)						20,000
Issuance of common stock upon the exercise of stock options	209							209
Net issuance of restricted stock awards (in shares)						28,000
Net issuance of restricted stock awards	1					$ 1
Treasury stock acquired from employees upon vesting or forfeiture of restricted stock (in shares)														7,000
Treasury stock acquired from employees upon vesting or forfeiture of restricted stock	(497)													$ (497)
Issuance of restricted stock for acquisition (in shares)						1,493,000
Issuance of restricted stock for acquisition	108,659					$ 30		108,629
Issuance of common stock (in shares)						(2,353,000)
Issuance of common stock	155,687					$ 47		155,640
Stock-based compensation	4,251							4,251
Foreign currency translation adjustments	355												355
Net loss	(9,956)											(9,956)
Ending Balance (in shares) at Jun. 30, 2021						26,998,000								1,149,000
Ending Balance at Jun. 30, 2021	436,561					$ 540		514,295				(64,933)	(3,883)	$ (9,458)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of stock options (in shares)						22,000
Issuance of common stock upon the exercise of stock options	200					$ 1		199
Net issuance of restricted stock awards (in shares)						15,000
Treasury stock acquired from employees upon vesting or forfeiture of restricted stock (in shares)														12,000
Treasury stock acquired from employees upon vesting or forfeiture of restricted stock	(458)													$ (458)
Issuance of restricted stock for acquisition	1,081							1,081
Issuance of common stock (in shares)							(982,000)
Issuance of common stock	63,068			$ 52,486			$ 19	63,068			$ 52,467
Stock-based compensation	3,785							3,785
Foreign currency translation adjustments	(109)												(109)
Net loss	$ (31,933)											(31,933)
Ending Balance (in shares) at Sep. 30, 2021	26,855,578					28,017,000								1,161,000
Ending Balance at Sep. 30, 2021	$ 524,681					$ 560		$ 634,895				$ (96,866)	$ (3,992)	$ (9,916)