Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings (Deficit) [Member]	Treasury Stock [Member]
Beginning Balance at Dec. 31, 2019	$ 449,175	$ 1,404	$ 123,294	$ 561,680	$ (237,203)
Beginning Balance, Shares at Dec. 31, 2019		116,481,442			23,893,484
Net income	42,402			42,402
Employee stock plans	299		299
Employee stock plans, Shares		32,772
Shares withheld for taxes on awards	(3,856)		(3,856)
Shares withheld for taxes on awards, Shares		(76,284)
Stock-based compensation	2,775		2,775
Stock-based compensation, Shares		152,408
Repurchases of common stock	(39,072)				$ (39,072)
Repurchases of common stock, Shares		(884,018)			884,018
Ending Balance at Mar. 31, 2020	451,723	$ 1,404	122,512	604,082	$ (276,275)
Ending Balance, Shares at Mar. 31, 2020		115,706,320			24,777,502
Beginning Balance at Dec. 31, 2020	588,531	$ 1,406	126,087	737,311	$ (276,273)
Beginning Balance, Shares at Dec. 31, 2020		115,799,503			24,777,502
Net income	48,545			48,545
Employee stock plans	460		460
Employee stock plans, Shares		28,286
Shares withheld for taxes on awards	(4,045)		(4,045)
Shares withheld for taxes on awards, Shares		(38,212)
Stock-based compensation	2,176		2,176
Stock-based compensation, Shares		76,094
Repurchases of common stock	(45,523)				$ (45,523)
Repurchases of common stock, Shares		(504,275)			504,275
Ending Balance at Mar. 31, 2021	$ 590,144	$ 1,406	$ 124,678	$ 785,856	$ (321,796)
Ending Balance, Shares at Mar. 31, 2021		115,361,396			25,281,777