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	(903)	536	(325)		(1,114)
Net tax effect of stock options exercised and release of unvested shares	(1,805)		(1,805)
Stock-based compensation	5,130		5,130
Dividends paid ($0.085 and $0.17 per share for the nine months ended September 30, 2016 and September 30, 2015, respectively)	(15,952)			(15,952)
Treasury stock issued	138		(77)		215
Purchase of treasury stock	(4,542)				(4,542)
Net loss	(173,473)			(173,473)
Other comprehensive income	1,497					1,497
Balance at Sep. 30, 2015	136,766	120,143	349,162	976,282	(1,263,089)	(45,732)
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	(229)	284	(284)		(229)
Net tax effect of stock options exercised and release of unvested shares	(1,091)		(1,091)
Stock-based compensation	2,241		2,241
Dividends paid ($0.085 and $0.17 per share for the nine months ended September 30, 2016 and September 30, 2015, respectively)	(5,285)			(5,285)
Treasury stock issued	130		(2,905)		3,035
Net loss	(12,906)			(12,906)
Other comprehensive income	(618)					(618)
Balance at Sep. 30, 2016	$ 122,558	$ 120,431	$ 351,011	$ 955,347	$ (1,260,053)	$ (44,178)