UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income	Cumulative Effect Period of Adoption Adjustment	Cumulative Effect Period of Adoption Adjustment Retained Earnings
Beginning balance (in shares) at Dec. 31, 2019		21,964,809
Beginning balance at Dec. 31, 2019	$ 1,462,710	$ 220	$ 1,309,438	$ 152,819	$ 233	$ (3,311)	$ (3,311)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	6,884		6,883	1
Exercise of stock options, net (in shares)		19,567
Exercise of stock options, net	1,185		1,185
Issuance of restricted stock, net (in shares)		240,329
Issuance of restricted stock, net	(25,802)	$ 2	(25,804)
Repurchase of common stock (in shares)		(1,769)
Repurchase of common stock	(247)		(105)	(142)
Common stock dividends	(26,686)			(26,686)
Foreign currency translation adjustment	0
Unrealized gains (losses) on marketable securities, net of tax	426				426
Net income	69,391			69,391
Ending balance (in shares) at Jun. 30, 2020		22,222,936
Ending balance at Jun. 30, 2020	1,484,550	$ 222	1,291,597	192,072	659
Beginning balance (in shares) at Mar. 31, 2020		22,213,587
Beginning balance at Mar. 31, 2020	1,459,147	$ 222	1,287,406	171,266	253
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	3,859		3,858	1
Exercise of stock options, net (in shares)		5,252
Exercise of stock options, net	339		339
Issuance of restricted stock, net (in shares)		4,097
Issuance of restricted stock, net	(6)		(6)
Common stock dividends	(13,347)			(13,347)
Foreign currency translation adjustment	0
Unrealized gains (losses) on marketable securities, net of tax	406				406
Net income	34,152			34,152
Ending balance (in shares) at Jun. 30, 2020		22,222,936
Ending balance at Jun. 30, 2020	1,484,550	$ 222	1,291,597	192,072	659
Beginning balance (in shares) at Dec. 31, 2020		24,418,939
Beginning balance at Dec. 31, 2020	1,748,319	$ 244	1,519,549	179,646	48,880
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	8,068		8,035	33
Exercise of stock options, net (in shares)		1,632
Exercise of stock options, net	113		113
Issuance of restricted stock, net (in shares)		238,034
Issuance of restricted stock, net	(2,340)	$ 2	(2,342)
Repurchase of common stock (in shares)		(37,494)
Repurchase of common stock	(2,904)		(2,333)	(571)
Common stock dividends	(29,572)			(29,572)
Foreign currency translation adjustment	(17,988)				(17,988)
Unrealized gains (losses) on marketable securities, net of tax	(69)				(69)
Net income	29,553			29,553
Ending balance (in shares) at Jun. 30, 2021		24,621,111
Ending balance at Jun. 30, 2021	1,733,180	$ 246	1,523,022	179,089	30,823
Beginning balance (in shares) at Mar. 31, 2021		24,651,205
Beginning balance at Mar. 31, 2021	1,735,925	$ 247	1,521,145	174,469	40,064
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	4,168		4,167	1
Exercise of stock options, net (in shares)		833
Exercise of stock options, net	43		43
Issuance of restricted stock, net (in shares)		6,567
Issuance of restricted stock, net	(1)	$ (1)
Repurchase of common stock (in shares)		(37,494)
Repurchase of common stock	(2,904)		(2,333)	(571)
Common stock dividends	(14,786)			(14,786)
Foreign currency translation adjustment	(9,276)				(9,276)
Unrealized gains (losses) on marketable securities, net of tax	35				35
Net income	19,976			19,976
Ending balance (in shares) at Jun. 30, 2021		24,621,111
Ending balance at Jun. 30, 2021	$ 1,733,180	$ 246	$ 1,523,022	$ 179,089	$ 30,823