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, 2014	$ 625,458	$ 992	$ 521,228	$ (31,992)	$ 262,616	$ (127,386)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(3,261)				(3,261)
Employee stock options, restricted stock and employee stock purchase plan	(1,101)	2	(507)			(596)
Stock-based compensation expense	6,510		6,510
Income tax effect, net, of employee stock related activity	(396)		(396)
Foreign currency translation adjustments	(15,890)			(15,890)
Other	(870)		(870)
Ending balance at Jun. 30, 2015	610,450	994	525,965	(47,882)	259,355	(127,982)
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 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 adjustments	869			869
Ending balance at Jun. 30, 2016	$ 497,687	$ 997	$ 537,108	$ (57,407)	$ 143,756	$ (126,767)