CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balance at Dec. 31, 2019	$ 726,283	$ 360	$ (6,030)	$ 666,585	$ 68,109	$ (2,741)
Net income	28,954				28,954
Foreign currency translation	(988)					(988)
Stock-based compensation expense	5,445			5,445
Stock options exercised	1,343	1		1,342
Repurchases of common stock	(43,238)	(6)			(43,232)
Balance at Mar. 31, 2020	717,799	355	(6,030)	673,372	53,831	(3,729)
Balance at Dec. 31, 2020	805,779	355	(5,578)	695,904	115,229	(131)
Net income	43,306				43,306
Foreign currency translation	(2,135)					(2,135)
Stock-based compensation expense	2,871			2,871
Stock options exercised	9,106	4		9,102
Balance at Mar. 31, 2021	$ 858,927	$ 359	$ (5,578)	$ 707,877	$ 158,535	$ (2,266)