Condensed Consolidated Statements of Changes in Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
Beginning Balance at Dec. 31, 2018	$ 826,609	$ 428	$ 286,544	$ 598,788	$ (56,775)	$ (2,376)
Beginning Balance, shares at Dec. 31, 2018		42,778
Stock-based compensation expense	1,890		1,890
Issuance of common stock under equity award plans, net of forfeitures		$ (2)	182			(180)
Issuance of common stock under equity award plans, net of forfeitures, Share		(168)
Shares repurchased for tax withholding on equity awards	(1,269)		(1,269)
Shares repurchased for tax withholding on equity awards, Share		(45)
Comprehensive income (loss)	14,701			11,687	3,014
Ending Balance at Mar. 31, 2019	842,041	$ 426	287,347	610,585	(53,761)	(2,556)
Ending Balance, shares at Mar. 31, 2019		42,565
Cumulative effect of accounting change | Accounting Standards Update 2016-02 [Member]	110			110
Beginning Balance at Dec. 31, 2019	874,475	$ 416	288,935	634,668	(47,001)	(2,543)
Beginning Balance, shares at Dec. 31, 2019		41,549
Stock-based compensation expense	1,860		1,860
Issuance of common stock under equity award plans, net of forfeitures		$ (2)	69			(67)
Issuance of common stock under equity award plans, net of forfeitures, Share		(146)
Shares repurchased for tax withholding on equity awards	(1,009)		(1,009)
Shares repurchased for tax withholding on equity awards, Share		(39)
Repurchase of common stock	(22,909)					(22,909)
Retirement of treasury stock		$ (9)	(26)	(22,874)		22,909
Retirement of treasury stock, shares		(860)
Comprehensive income (loss)	(8,813)			13,918	(22,731)
Ending Balance at Mar. 31, 2020	$ 843,604	$ 405	$ 289,829	$ 625,712	$ (69,732)	$ (2,610)
Ending Balance, shares at Mar. 31, 2020		40,504