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, 2012	$ 606,264	$ 438	$ 277,192	$ 315,187	$ 14,856	$ (1,409)
Beginning Balance, shares at Dec. 31, 2012		43,790
Issuance of common stock	59		59
Issuance of common stock, shares		10
Stock-based compensation expense	4,873		4,873
Excess tax benefit (deficiency) from stock-based compensation	(187)		(187)
Issuance of common stock under equity award plans, net of shares withheld for employee taxes	(227)	$ 5	(29)			(203)
Issuance of common stock under equity award plans, net of shares withheld for employee taxes, shares		538
Repurchase of common stock	(5,479)					(5,479)
Retirement of treasury stock		$ (3)	(2,395)	(3,081)		5,479
Retirement of treasury stock, shares		(341)
Comprehensive income (loss)	30,401			37,260	(6,859)
Ending Balance at Dec. 31, 2013	635,704	$ 440	279,513	349,366	7,997	(1,612)
Ending Balance, shares at Dec. 31, 2013		43,997
Stock-based compensation expense	6,381		6,381
Excess tax benefit (deficiency) from stock-based compensation	(82)		(82)
Issuance of common stock under equity award plans, net of shares withheld for employee taxes	(437)	$ (1)	(592)			156
Issuance of common stock under equity award plans, net of shares withheld for employee taxes, shares		(76)
Repurchase of common stock	(12,581)					(12,581)
Retirement of treasury stock		$ (6)	(5,932)	(6,643)		12,581
Retirement of treasury stock, shares		(630)
Comprehensive income (loss)	29,233			57,791	(28,558)
Ending Balance at Dec. 31, 2014	658,218	$ 433	279,288	400,514	(20,561)	(1,456)
Ending Balance, shares at Dec. 31, 2014		43,291
Stock-based compensation expense	8,749		8,749
Excess tax benefit (deficiency) from stock-based compensation	422		422
Issuance of common stock under equity award plans, net of shares withheld for employee taxes	(3,326)	$ 4	(3,159)			(171)
Issuance of common stock under equity award plans, net of shares withheld for employee taxes, shares		348
Repurchase of common stock	(20,879)					(20,879)
Retirement of treasury stock		$ (9)	(9,920)	(10,786)		20,715
Retirement of treasury stock, shares		(854)
Comprehensive income (loss)	35,496			68,597	(33,101)
Ending Balance at Dec. 31, 2015	$ 678,680	$ 428	$ 275,380	$ 458,325	$ (53,662)	$ (1,791)
Ending Balance, shares at Dec. 31, 2015		42,785