Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2017	$ 179,189	$ 0	$ 179,448	$ (259)
Balance, shares at Dec. 31, 2017		30,305
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	14,658		14,658
Unrealized loss on marketable securities, net of income tax expense	58			58
Gain (loss) on derivative securities, effective portion, net of income tax (benefit) expense	7			7
Foreign currency translation adjustment, including income tax expense (benefit)	(715)			(715)
Stock-based compensation expense	1,981	$ 1,981	0
Common stock issued under equity compensation plan, net of shares withheld for tax payments, in shares		192
Common stock issued under equity compensation plan, net of shares withheld for tax payments	(30)	$ (30)
Common stock issued under employee stock purchase plan, shares		38
Common stock issued under employee stock purchase plan	444	$ 444
Repurchased shares, in shares		(990)
Repurchased shares	(12,996)	$ (2,180)	(10,816)
Balance, shares at Dec. 31, 2018		29,545
Ending balance at Dec. 31, 2018	182,596	$ 215	183,290	(909)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(92,800)		(92,800)
Unrealized loss on marketable securities, net of income tax expense	6			6
Gain (loss) on derivative securities, effective portion, net of income tax (benefit) expense	(223)			(223)
Foreign currency translation adjustment, including income tax expense (benefit)	189			189
Stock-based compensation expense	619	$ 837	(218)
Common stock issued under equity compensation plan, net of shares withheld for tax payments, in shares		135
Common stock issued under equity compensation plan, net of shares withheld for tax payments	(32)	$ (32)
Common stock issued under employee stock purchase plan, shares		101
Common stock issued under employee stock purchase plan	241	$ 241
Balance, shares at Dec. 31, 2019		29,781
Ending balance at Dec. 31, 2019	90,596	$ 1,261	90,272	(937)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	59,848		59,848
Unrealized loss on marketable securities, net of income tax expense	(4)			(4)
Foreign currency translation adjustment, including income tax expense (benefit)	955			955
Stock-based compensation expense	3,734	$ 3,734
Common stock issued under equity compensation plan, net of shares withheld for tax payments, in shares		455
Common stock issued under equity compensation plan, net of shares withheld for tax payments	(2,190)	$ (2,190)
Common stock issued under employee stock purchase plan, shares		94
Common stock issued under employee stock purchase plan	256	$ 256
Balance, shares at Dec. 31, 2020		30,330
Ending balance at Dec. 31, 2020	$ 153,195	$ 3,061	$ 150,120	$ 14