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, 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, net of tax				211	211
Exercise of stock options (in shares)	396
Exercise of stock options		3,687			3,687
Issuance of stock under Employee Stock Purchase Plan (in shares)	26
Issuance of stock under Employee Stock Purchase Plan		1,179			1,179
Issuance of restricted common shares (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
Increase (Decrease) in Stockholders' Equity
Net income			183,079		183,079
Foreign currency translation adjustments				(4,058)	(4,058)
Change in pension obligation, net of tax				325	325
Exercise of stock options (in shares)	103
Exercise of stock options		1,247			1,247
Issuance of stock under Employee Stock Purchase Plan (in shares)	29
Issuance of stock under Employee Stock Purchase Plan		1,662			1,662
Issuance of restricted common shares (in shares)	291
Issuance of restricted common shares		(9,907)			(9,907)
Stock-based compensation expense		13,444			13,444
Repurchase of common stock (in shares)	(888)
Repurchase of common stock		(16,030)	(41,465)		(57,495)
Balance (in shares) at Dec. 31, 2022	32,775
Balance at Dec. 31, 2022	$ 33	550,299	118,892	(1,968)	667,256
Increase (Decrease) in Stockholders' Equity
Net income			246,263		246,263
Foreign currency translation adjustments				38	38
Change in pension obligation, net of tax				84	84
Exercise of stock options (in shares)	3
Exercise of stock options		25			25
Issuance of stock under Employee Stock Purchase Plan (in shares)	16
Issuance of stock under Employee Stock Purchase Plan		2,057			2,057
Issuance of restricted common shares (in shares)	271
Issuance of restricted common shares		(16,611)			(16,611)
Stock-based compensation expense		18,269			18,269
Repurchase of common stock (in shares)	(380)
Repurchase of common stock		(6,850)	(45,649)		(52,499)
Balance (in shares) at Dec. 31, 2023	32,685
Balance at Dec. 31, 2023	$ 33	$ 547,189	$ 319,506	$ (1,846)	$ 864,882