CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Loss
Beginning balance at Dec. 31, 2019	$ 1,129,968	$ 702	$ 667,658	$ 930,830	$ (377,639)	$ (91,583)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	5,514			5,514
Other comprehensive income (loss)	(4,909)					(4,909)
Stock-based compensation	22,943		22,943
Shares issued and forfeited, net, under stock plans	9,359		(14,660)		24,019
Repurchase of common stock	(28,881)				(28,881)
Repurchase of stock-based compensation awards for tax withholdings	(11,150)				(11,150)
Ending balance at Sep. 30, 2020	1,122,844	702	675,941	936,344	(393,651)	(96,492)
Beginning balance at Jun. 30, 2020	1,090,737	702	667,554	920,478	(399,663)	(98,334)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	15,866			15,866
Other comprehensive income (loss)	1,842					1,842
Stock-based compensation	8,061		8,061
Shares issued and forfeited, net, under stock plans	6,364		326		6,038
Repurchase of stock-based compensation awards for tax withholdings	(26)				(26)
Ending balance at Sep. 30, 2020	1,122,844	702	675,941	936,344	(393,651)	(96,492)
Beginning balance at Dec. 31, 2020	1,206,597	702	682,431	1,003,490	(387,581)	(92,445)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	18,320			18,320
Other comprehensive income (loss)	(5,873)					(5,873)
Stock-based compensation	20,790		20,790
Shares issued and forfeited, net, under stock plans	9,964		(20,177)		30,141
Repurchase of common stock	(39,411)				(39,411)
Repurchase of stock-based compensation awards for tax withholdings	(14,833)				(14,833)
Ending balance at Sep. 30, 2021	1,195,554	702	683,044	1,021,810	(411,684)	(98,318)
Beginning balance at Jun. 30, 2021	1,178,560	702	676,399	1,008,046	(412,492)	(94,095)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	13,764			13,764
Other comprehensive income (loss)	(4,223)					(4,223)
Stock-based compensation	6,367		6,367
Shares issued and forfeited, net, under stock plans	1,123		278		845
Repurchase of stock-based compensation awards for tax withholdings	(37)				(37)
Ending balance at Sep. 30, 2021	$ 1,195,554	$ 702	$ 683,044	$ 1,021,810	$ (411,684)	$ (98,318)