Condensed Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)
Balance at Dec. 31, 2014	$ 326,676	$ 119,607	$ 346,239	$ 1,165,707	$ (1,257,648)	$ (47,229)
Increase (Decrease) in Stockholders' Equity
Exercise of stock options and release of unvested shares	(385)	312	(102)		(595)
Net tax effect of stock options exercised and release of unvested shares	(1,269)		(1,269)
Stock-based compensation	2,568		2,568
Dividends paid ($0.085 and $0.17 per share for the six months ended June 30, 2016 and June 30, 2015, respectively)	(10,658)			(10,658)
Treasury stock issued	109		(18)		127
Purchase of treasury stock	(2,343)				(2,343)
Net loss	(2,558)			(2,558)
Other comprehensive income	1,640					1,640
Balance at Jun. 30, 2015	313,780	119,919	347,418	1,152,491	(1,260,459)	(45,589)
Balance at Dec. 31, 2015	140,316	120,147	353,050	973,538	(1,262,859)	(43,560)
Increase (Decrease) in Stockholders' Equity
Exercise of stock options and release of unvested shares	(184)	251	(251)		(184)
Net tax effect of stock options exercised and release of unvested shares	(914)		(914)
Stock-based compensation	1,523		1,523
Dividends paid ($0.085 and $0.17 per share for the six months ended June 30, 2016 and June 30, 2015, respectively)	(5,285)			(5,285)
Treasury stock issued	67		(694)		761
Net loss	(9,866)			(9,866)
Other comprehensive income	(539)					(539)
Balance at Jun. 30, 2016	$ 125,118	$ 120,398	$ 352,714	$ 958,387	$ (1,262,282)	$ (44,099)