Condensed Consolidated Statements of Changes in Equity (USD $) In Thousands, unless otherwise specified	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Balance at Dec. 31, 2012	$ 118,737	$ 341,586	$ 1,165,952	$ (1,248,377)	$ (49,734)	$ 328,164
Increase (Decrease) in Stockholders' Equity
Exercise of stock options and release of unvested shares	450	469		(407)		512
Net tax effect of stock options exercised and release of unvested shares		(2,606)				(2,606)
Stock-based compensation		5,744				5,744
Dividends paid ($0.17 and $0.255 per share for six months ended June 30, 2014 and twelve months ended December 31, 2013, respectively)			(16,121)			(16,121)
Treasury stock issued		(98)		135		37
Purchase of treasury stock				(1,662)		(1,662)
Net income			13,370			13,370
Other comprehensive income (loss)					21,616	21,616
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	300	(74)		(580)		(354)
Net tax effect of stock options exercised and release of unvested shares		(1,080)				(1,080)
Stock-based compensation		2,392				2,392
Dividends paid ($0.17 and $0.255 per share for six months ended June 30, 2014 and twelve months ended December 31, 2013, respectively)			(10,788)			(10,788)
Treasury stock issued		(281)		395		114
Purchase of treasury stock				(2,086)		(2,086)
Net income			7,482			7,482
Other comprehensive income (loss)					1,663	1,663
Balance at Jun. 30, 2014	$ 119,487	$ 346,052	$ 1,159,895	$ (1,252,582)	$ (26,455)	$ 346,397