Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]
Beginning Balance at Dec. 31, 2018	$ 342,963	$ 1,400	$ 123,524	$ 416,942	$ (198,903)
Beginning Balance, Shares at Dec. 31, 2018		117,103,306			22,893,366
Net income	144,738			144,738
Employee stock plans	1,089	$ 2	1,087
Employee stock plans, Shares		154,282
Shares withheld for taxes on awards	(8,245)		(8,245)
Shares withheld for taxes on awards, Shares		(216,756)
Stock-based compensation	6,930	$ 2	6,928
Stock-based compensation, Shares		440,728
Repurchases of common stock	(38,300)				$ (38,300)
Repurchases of common stock, Shares		(1,000,118)			1,000,118
Ending Balance at Dec. 31, 2019	449,175	$ 1,404	123,294	561,680	$ (237,203)
Ending Balance, Shares at Dec. 31, 2019		116,481,442			23,893,484
Net income	175,631			175,631
Employee stock plans	1,446	$ 0	1,446
Employee stock plans, Shares		68,061
Shares withheld for taxes on awards	(5,784)		(5,784)
Shares withheld for taxes on awards, Shares		(111,433)
Stock-based compensation	7,133	$ 2	7,131
Stock-based compensation, Shares		245,451
Repurchases of common stock	(39,070)				$ (39,070)
Repurchases of common stock, Shares		(884,018)			884,018
Ending Balance at Dec. 31, 2020	588,531	$ 1,406	126,087	737,311	$ (276,273)
Ending Balance, Shares at Dec. 31, 2020		115,799,503			24,777,502
Net income	208,737			208,737
Employee stock plans	1,800		1,800
Employee stock plans, Shares		113,242
Shares withheld for taxes on awards	(8,538)		(8,538)
Shares withheld for taxes on awards, Shares		(78,626)
Stock-based compensation	8,439	$ 1	8,438
Stock-based compensation, Shares		123,132
Repurchases of common stock	(73,935)				$ (73,935)
Repurchases of common stock, Shares		(809,099)			809,099
Ending Balance at Dec. 31, 2021	$ 725,034	$ 1,407	$ 127,787	$ 946,048	$ (350,208)
Ending Balance, Shares at Dec. 31, 2021		115,148,152			25,586,601