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, 2013	$ 349,054	$ 119,187	$ 345,095	$ 1,163,201	$ (1,250,311)	$ (28,118)
Increase (Decrease) in Stockholders' Equity
Exercise of stock options and release of unvested shares	(481)	420	(151)		(750)
Net tax effect of stock options exercised and release of unvested shares	(1,993)		(1,993)
Stock-based compensation	4,055		4,055
Dividends paid ($0.26 and $0.34 per share for the nine months ended September 30, 2015 and twelve months ended December 31, 2014, respectively)	(21,485)			(21,485)
Treasury stock issued	540		(767)		1,307
Purchase of treasury stock	(7,894)				(7,894)
Net income (loss)	23,991			23,991
Other comprehensive loss/(gain)	(19,111)					(19,111)
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 ($0.26 and $0.34 per share for the nine months ended September 30, 2015 and twelve months ended December 31, 2014, respectively)	(15,952)			(15,952)
Treasury stock issued	138		(77)		215
Purchase of treasury stock	(4,542)				(4,542)
Net income (loss)	(173,473)			(173,473)
Other comprehensive loss/(gain)	1,497					1,497
Balance at Sep. 30, 2015	$ 136,766	$ 120,143	$ 349,162	$ 976,282	$ (1,263,089)	$ (45,732)