CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Retained Earnings (Accumulated Deficit)
Beginning balance (in shares) at Dec. 31, 2018		115,031
Beginning balance at Dec. 31, 2018	$ 275,882	$ 117	$ 417,228	$ (23,657)	$ (70)	$ (117,736)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of options (in shares)	1,500	1,497
Issuance of common stock upon exercise of options	$ 3,366	$ 1	3,365
Shares tendered to satisfy cost and statutory withholding requirements for net settlement of cashless option exercise (in shares)		(428)
Shares tendered to satisfy cost and statutory withholding requirements for net settlement of cashless option exercise	(5,100)			(5,100)
Stock-based compensation related to employee and director options	6,724		6,724
Other comprehensive income, net of tax	164				164
Purchases of treasury stock (in shares)		(1,168)
Purchases of treasury stock	(13,555)			(13,555)
Net income	18,274					18,274
Ending balance (in shares) at Mar. 31, 2019		114,932
Ending balance at Mar. 31, 2019	285,755	$ 118	427,317	(42,312)	94	(99,462)
Beginning balance (in shares) at Dec. 31, 2019		114,549
Beginning balance at Dec. 31, 2019	$ 371,182	$ 120	457,060	(62,704)	261	(23,555)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of options (in shares)	100	67
Issuance of common stock upon exercise of options	$ 480	$ 0	480
Stock-based compensation related to employee and director options	7,988		7,988
Other comprehensive income, net of tax	49				49
Purchases of treasury stock (in shares)		(20)
Purchases of treasury stock	(275)			(275)
Net income	30,065					30,065
Ending balance (in shares) at Mar. 31, 2020		114,596
Ending balance at Mar. 31, 2020	$ 409,489	$ 120	$ 465,528	$ (62,979)	$ 310	$ 6,510