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	(203,879)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	19,768	19,768
Other comprehensive income (loss)	(2,905)		(2,905)
Treasury shares purchased	(891)				$ (891)
Treasury shares purchased (in shares)					(8,224)
Shares and options (canceled) issued under stock plans	6,632			$ 3	$ 7,266	(637)
Shares and options (canceled) 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	(130,573)
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	(203,879)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	62,461
Other comprehensive income (loss)	4,347
Ending balance at Sep. 30, 2020	819,443	653,382	(1,217)	$ 2,164	$ (10,046)	175,160
Ending balance, common stock (in shares) at Sep. 30, 2020				32,451,415	(108,813)
Beginning balance at Mar. 31, 2020	766,271	610,689	(8,469)	$ 2,164	$ (11,694)	173,581
Beginning balance, common stock (in shares) at Mar. 31, 2020				32,447,415	(130,573)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	21,125	21,125
Other comprehensive income (loss)	2,575		2,575
Treasury shares purchased	(2,134)				$ (2,134)
Treasury shares purchased (in shares)					(24,281)
Shares and options (canceled) issued under stock plans	4,686				$ 4,194	492
Shares and options (canceled) issued under stock plans (in shares)				4,000	44,935
Ending balance at Jun. 30, 2020	792,523	631,814	(5,894)	$ 2,164	$ (9,634)	174,073
Ending balance, common stock (in shares) at Jun. 30, 2020				32,451,415	(109,919)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	21,568	21,568
Other comprehensive income (loss)	4,677		4,677
Treasury shares purchased	(2,957)				$ (2,957)
Treasury shares purchased (in shares)					(31,224)
Shares and options (canceled) issued under stock plans	3,632				$ 2,545	1,087
Shares and options (canceled) issued under stock plans (in shares)					32,330
Ending balance at Sep. 30, 2020	819,443	653,382	(1,217)	$ 2,164	$ (10,046)	175,160
Ending balance, common stock (in shares) at Sep. 30, 2020				32,451,415	(108,813)
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	32,372,621			32,448,705	(76,084)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	$ 23,411	23,411
Other comprehensive income (loss)	(5,624)		(5,624)
Treasury shares purchased	(1,596)				$ (1,596)
Treasury shares purchased (in shares)					(13,475)
Shares and options (canceled) issued under stock plans	5,068			$ 1	$ 7,259	(2,192)
Shares and options (canceled) 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	(19,089)
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	32,372,621			32,448,705	(76,084)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	$ 71,155
Other comprehensive income (loss)	(6,751)
Ending balance at Sep. 30, 2021	$ 889,078	727,895	(2,578)	$ 2,165	$ (11,080)	172,676
Ending balance, common stock (in shares) at Sep. 30, 2021	32,382,637			32,467,909	(85,272)
Beginning balance at Mar. 31, 2021	$ 849,492	680,151	(1,451)	$ 2,165	$ (2,210)	170,837
Beginning balance, common stock (in shares) at Mar. 31, 2021				32,471,019	(19,089)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	22,731	22,731
Other comprehensive income (loss)	1,883		1,883
Treasury shares purchased	(9,240)				$ (9,240)
Treasury shares purchased (in shares)					(72,649)
Shares and options (canceled) issued under stock plans	4,776				$ 2,978	1,798
Shares and options (canceled) issued under stock plans (in shares)				(190)	25,683
Ending balance at Jun. 30, 2021	869,642	702,882	432	$ 2,165	$ (8,472)	172,635
Ending balance, common stock (in shares) at Jun. 30, 2021				32,470,829	(66,055)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	25,013	25,013
Other comprehensive income (loss)	(3,010)		(3,010)
Treasury shares purchased	(7,926)				$ (7,926)
Treasury shares purchased (in shares)					(61,075)
Shares and options (canceled) issued under stock plans	5,359				$ 5,318	41
Shares and options (canceled) issued under stock plans (in shares)				(2,920)	41,858
Ending balance at Sep. 30, 2021	$ 889,078	$ 727,895	$ (2,578)	$ 2,165	$ (11,080)	$ 172,676
Ending balance, common stock (in shares) at Sep. 30, 2021	32,382,637			32,467,909	(85,272)