CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Retained Earnings	Total
Beginning balance at Dec. 31, 2019	$ 28	$ 152,117	$ (3,130)	$ 575,531
Common stock issued under employee stock plans	0	5,529
Repurchase of common stock	0	(2,013)
Stock-based compensation		6,710
Other comprehensive loss			(1,184)		$ (1,184)
Net income				15,886	15,886
Payment of dividends to stockholders				(5,644)
Ending balance at Mar. 31, 2020	28	162,343	(4,314)	585,773	743,830
Beginning balance at Dec. 31, 2020	28	190,920	(2,163)	621,626	810,411
Common stock issued under employee stock plans	1	3,651
Repurchase of common stock	0	0
Stock-based compensation		8,480
Other comprehensive loss			(673)		(673)
Net income				39,798	39,798
Payment of dividends to stockholders				(7,845)
Ending balance at Mar. 31, 2021	$ 29	$ 203,051	$ (2,836)	$ 653,579	$ 853,823