Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Paid-In Capital	Accumulated Other Comprehensive Loss	Retained Earnings	Treasury Stock
Beginning balance at Dec. 31, 2015	$ 520,259	$ 994	$ 533,746	$ (58,276)	$ 171,788	$ (127,993)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(27,204)				(27,204)
Employee stock options, restricted stock and employee stock purchase plan	(798)	3	(1,199)		(828)	1,226
Stock-based compensation expense	5,613		5,613
Income tax effect, net, of employee stock related activity	(1,052)		(1,052)
Foreign currency translation	869			869
Ending balance at Jun. 30, 2016	497,687	997	537,108	(57,407)	143,756	(126,767)
Beginning balance at Dec. 31, 2016	500,543	998	558,966	(63,208)	129,873	(126,086)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	649				649
Employee stock options, restricted stock and employee stock purchase plan	(586)	11	728		(237)	(1,088)
Stock-based compensation expense	5,874		5,874
Foreign currency translation	7,824			7,824
Ending balance at Jun. 30, 2017	$ 514,304	$ 1,009	$ 565,568	$ (55,384)	$ 130,285	$ (127,174)