Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Total
Balance (in shares) at Dec. 31, 2018	32,558
Balance at Dec. 31, 2018	$ 33	$ 565,116	$ (157,260)	$ 448	$ 408,337
Increase (Decrease) in Stockholders' Equity
Net income			17,034		17,034
Foreign currency translation adjustments				(444)	(444)
Change in pension obligation				(262)	(262)
Exercise of stock options (in shares)	775
Exercise of stock options	$ 1	5,104			5,105
Issuance of shares under Employee Stock Purchase Plan (in shares)	54
Issuance of shares under Employee Stock Purchase Plan		1,016			1,016
Issuance of common shares on restricted stock units, net of shares withheld (in shares)	250
Issuance of restricted common shares		(1,633)			(1,633)
Stock-based compensation expense		8,018			8,018
Repurchase of common stock (in shares)	(1,052)
Repurchase of common stock	$ (1)	(17,743)			(17,744)
Balance (in shares) at Dec. 31, 2019	32,585
Balance at Dec. 31, 2019	$ 33	559,878	(140,226)	(258)	419,427
Increase (Decrease) in Stockholders' Equity
Net income			49,982		49,982
Foreign currency translation adjustments				3,427	3,427
Change in pension obligation				266	266
Exercise of stock options (in shares)	1,001
Exercise of stock options	$ 1	8,418			8,419
Issuance of shares under Employee Stock Purchase Plan (in shares)	41
Issuance of shares under Employee Stock Purchase Plan		1,011			1,011
Issuance of common shares on restricted stock units, net of shares withheld (in shares)	364
Issuance of restricted common shares		(3,915)			(3,915)
Stock-based compensation expense		10,485			10,485
Repurchase of common stock (in shares)	(358)
Repurchase of common stock		(5,775)	(1,725)		(7,500)
Balance (in shares) at Dec. 31, 2020	33,633
Balance at Dec. 31, 2020	$ 34	570,102	(91,969)	3,435	481,602
Increase (Decrease) in Stockholders' Equity
Net income			98,650		98,650
Foreign currency translation adjustments				(1,881)	(1,881)
Change in pension obligation				211	211
Exercise of stock options (in shares)	396
Exercise of stock options		3,687			3,687
Issuance of shares under Employee Stock Purchase Plan (in shares)	26
Issuance of shares under Employee Stock Purchase Plan		1,179			1,179
Issuance of common shares on restricted stock units, net of shares withheld (in shares)	326
Issuance of restricted common shares		(6,564)			(6,564)
Stock-based compensation expense		12,067			12,067
Repurchase of common stock (in shares)	(1,141)
Repurchase of common stock	$ (1)	(20,588)	(29,403)		(49,992)
Balance (in shares) at Dec. 31, 2021	33,240
Balance at Dec. 31, 2021	$ 33	$ 559,883	$ (22,722)	$ 1,765	$ 538,959