Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Retained Earnings	Accumulated Other Comprehensive (Loss) Income	Common Stock	Treasury Stock	Additional Paid-in Capital
Beginning balance at Dec. 31, 2019	$ 743,667	$ 590,921	$ (5,564)	$ 2,161	$ (18,069)	$ 174,218
Beginning balance, common stock (in shares) at Dec. 31, 2019				32,405,796
Beginning balance, treasury stock (in shares) at Dec. 31, 2019					(203,879)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	19,768	19,768
Other comprehensive (loss) income	(2,905)		(2,905)
Treasury shares purchased	(891)				$ (891)
Treasury shares purchased (in shares)					(8,224)
Shares and options issued under stock plans	6,632			$ 3	$ 7,266	(637)
Shares and options issued under stock plans (in shares)				41,619	81,530
Ending balance at Mar. 31, 2020	766,271	610,689	(8,469)	$ 2,164	$ (11,694)	173,581
Ending balance, common stock (in shares) at Mar. 31, 2020				32,447,415
Ending balance, treasury stock (in shares) at Mar. 31, 2020					(130,573)
Beginning balance at Dec. 31, 2020	828,233	656,740	4,173	$ 2,164	$ (7,873)	173,029
Beginning balance, common stock (in shares) at Dec. 31, 2020				32,448,705
Beginning balance, treasury stock (in shares) at Dec. 31, 2020					(76,084)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	23,411	23,411
Other comprehensive (loss) income	(5,624)		(5,624)
Treasury shares purchased	(1,596)				$ (1,596)
Treasury shares purchased (in shares)					(13,475)
Shares and options issued under stock plans	5,068			$ 1	$ 7,259	(2,192)
Shares and options issued under stock plans (in shares)				22,314	70,470
Ending balance at Mar. 31, 2021	$ 849,492	$ 680,151	$ (1,451)	$ 2,165	$ (2,210)	$ 170,837
Ending balance, common stock (in shares) at Mar. 31, 2021				32,471,019
Ending balance, treasury stock (in shares) at Mar. 31, 2021					(19,089)