Condensed Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Total
Balance at Dec. 31, 2013	$ 119,187	$ 345,095	$ 1,163,201	$ (1,250,311)	$ (28,118)	$ 349,054
Increase (Decrease) in Stockholders' Equity
Exercise of stock options and release of unvested shares	420	(151)		(750)		(481)
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 ($ 0.17 and $0.34 per share for the six months ended June 30, 2015 and twelve months ended December 31, 2014, respectively)			(21,485)			(21,485)
Treasury stock issued		(767)		1,307		540
Purchase of treasury stock				(7,894)		(7,894)
Net income (loss)			23,991			23,991
Other comprehensive loss/(gain)					(19,111)	(19,111)
Balance at Dec. 31, 2014	119,607	346,239	1,165,707	(1,257,648)	(47,229)	326,676
Increase (Decrease) in Stockholders' Equity
Exercise of stock options and release of unvested shares	312	(102)		(595)		(385)
Net tax effect of stock options exercised and release of unvested shares		(1,269)				(1,269)
Stock-based compensation		2,568				2,568
Dividends paid ($ 0.17 and $0.34 per share for the six months ended June 30, 2015 and twelve months ended December 31, 2014, respectively)			(10,658)			(10,658)
Treasury stock issued		(18)		127		109
Purchase of treasury stock				(2,343)		(2,343)
Net income (loss)			(2,558)			(2,558)
Other comprehensive loss/(gain)					1,640	1,640
Balance at Jun. 30, 2015	$ 119,919	$ 347,418	$ 1,152,491	$ (1,260,459)	$ (45,589)	$ 313,780