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 beginning of period at Dec. 31, 2015	$ 140,316	$ 120,147	$ 353,050	$ 973,538	$ (1,262,859)	$ (43,560)
Increase (Decrease) in Stockholders' Equity (Deficit)
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 for the three months ended March 31, 2016)	(5,285)			(5,285)
Treasury stock issued	67		(694)		761
Net loss	(9,866)			(9,866)
Other comprehensive loss	(539)					(539)
Balance at end of period at Jun. 30, 2016	125,118	120,398	352,714	958,387	(1,262,282)	(44,099)
Balance at beginning of period at Dec. 31, 2016	2,656	120,437	350,245	837,316	(1,259,164)	(46,178)
Increase (Decrease) in Stockholders' Equity (Deficit)
Cumulative effect of accounting change	(164)		709	(873)
Exercise of stock options and release of unvested shares	(92)	303	(303)		(92)
Stock-based compensation	1,110		1,110
Treasury stock issued	104		(1,984)		2,088
Net loss	(10,039)			(10,039)
Other comprehensive loss	1,395					1,395
Balance at end of period at Jun. 30, 2017	$ (5,030)	$ 120,740	$ 349,777	$ 826,404	$ (1,257,168)	$ (44,783)