Consolidated Statements Of Changes In Equity (USD $) In Thousands	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, 2010	$ 118,296	$ 336,795	$ 1,252,438	$ (1,236,024)	$ (33,682)	$ 437,823
Exercise of stock options and release of nonvested shares	191	522	0	(193)	0	520
Net tax effect of options exercised and release of nonvested shares	0	(959)	0	0	0	(959)
Stock-based compensation	0	4,988	0	0	0	4,988
Dividends paid	0	0	(20,370)	0	0	(20,370)
Treasury stock issued	0	(197)	0	356	0	159
Purchase of treasury stock	0	0	0	(8,363)	0	(8,363)
Net income	0	0	44,198	0	0	44,198
Other comprehensive income					(11,641)	(11,641)
Balance at Dec. 31, 2011	118,487	341,149	1,276,266	(1,244,224)	(45,323)	446,355
Exercise of stock options and release of nonvested shares	186	175	0	(179)	0	182
Net tax effect of options exercised and release of nonvested shares	0	(804)	0	0	0	(804)
Stock-based compensation	0	993	0	0	0	993
Dividends paid	0	0	(5,405)	0	0	(5,405)
Treasury stock issued	0	(58)	0	98	0	40
Net income	0	0	6,793	0	0	6,793
Other comprehensive income	0	0	0	0	1,787	1,787
Balance at Mar. 31, 2012	$ 118,673	$ 341,455	$ 1,277,654	$ (1,244,305)	$ (43,536)	$ 449,941