Consolidated Statements of Changes in Equity (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)
Balance at Dec. 31, 2011	$ 446,355	$ 118,487	$ 341,149	$ 1,276,266	$ (1,244,224)	$ (45,323)
Increase (Decrease) in Stockholders' Equity
Exercise of stock options and release of nonvested shares	455	250	410	0	(205)	0
Net tax effect of stock options exercised and release of nonvested shares	(3,082)	0	(3,082)	0	0	0
Stock-based compensation	3,412	0	3,412	0	0	0
Dividends paid ($0.43 per share)	(26,961)	0	0	(26,961)	0	0
Treasury stock issued	151	0	(303)	0	454	0
Purchase of treasury stock	(4,402)	0	0	0	(4,402)	0
Net income (loss)	(83,353)	0	0	(83,353)	0	0
Other comprehensive income	(4,411)	0	0	0	0	(4,411)
Balance at Dec. 31, 2012	328,164	118,737	341,586	1,165,952	(1,248,377)	(49,734)
Increase (Decrease) in Stockholders' Equity
Exercise of stock options and release of nonvested shares	(313)	220	(138)	0	(395)	0
Net tax effect of stock options exercised and release of nonvested shares	(801)	0	(801)	0	0	0
Stock-based compensation	1,288	0	1,288	0	0	0
Treasury stock issued	37	0	(98)	0	135	0
Purchase of treasury stock	(436)	0	0	0	(436)	0
Net income (loss)	6,667	0	0	6,667	0	0
Other comprehensive income	(127)	0	0	0	0	(127)
Balance at Mar. 31, 2013	$ 334,479	$ 118,957	$ 341,837	$ 1,172,619	$ (1,249,073)	$ (49,861)