Statements of Changes in Stockholders’ Equity - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Retained Earnings	Common Stock Held in Treasury	Accumulated Other Comprehensive Income/(Loss)	Total
Balance at Dec. 31, 2014	$ 522	$ 240,135	$ 487,462	$ (306,629)	$ (5,894)	$ 415,596
Increase (Decrease) in Stockholders' Equity
Net (loss) income			91,570			91,570
Other comprehensive (loss) income					(13,601)	(13,601)
Issuance of common stock in connection with employee stock option exercises and for restricted stock unit awards		(20,299)		20,621		322
Issuance of common stock for the employee stock purchase plan	1	1,166				1,167
Shares withheld for net settlements of share-based awards				(8,978)		(8,978)
Purchase of common stock for treasury				(42,046)		(42,046)
Dividend declared on common stock		2	(7,406)	109		(7,295)
Share-based compensation		18,086				18,086
Balance at Dec. 31, 2015	523	239,090	571,626	(336,923)	(19,495)	454,821
Increase (Decrease) in Stockholders' Equity
Net (loss) income			(25,918)			(25,918)
Other comprehensive (loss) income					(14,482)	(14,482)
Issuance of common stock in connection with employee stock option exercises and for restricted stock unit awards	1	(16,600)		19,237		2,638
Issuance of common stock for the employee stock purchase plan	1	1,320				1,321
Shares withheld for net settlements of share-based awards				(6,795)		(6,795)
Purchase of common stock for treasury				(22,112)		(22,112)
Dividend declared on common stock		4	(9,358)	111		(9,243)
Share-based compensation		24,934				24,934
Balance at Dec. 31, 2016	525	248,748	536,350	(346,482)	(33,977)	405,164
Increase (Decrease) in Stockholders' Equity
Net (loss) income			(39,440)			(39,440)
Other comprehensive (loss) income					12,580	12,580
Issuance of common stock in connection with employee stock option exercises and for restricted stock unit awards	1	(20,749)		21,026		278
Issuance of common stock for the employee stock purchase plan		1,098				1,098
Shares withheld for net settlements of share-based awards				(10,779)		(10,779)
Purchase of common stock for treasury				(16,933)		(16,933)
Dividend declared on common stock		15	(9,310)	101		(9,194)
Share-based compensation		20,238				20,238
Cumulative effect of accounting change		866	(643)			223
Balance at Dec. 31, 2017	$ 526	$ 250,216	$ 486,957	$ (353,067)	$ (21,397)	$ 363,235