Comprehensive Income (details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Accumulated Other Comprehensive Income Loss Net Of Tax Abstract
Accumulated other comprehensive income (loss)	$ (6,166)	$ (5,675)	$ (6,166)	$ (5,675)	$ (6,604)
Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent Abstract
Net income	(8,312)	(7,420)	34,654	43,076
Amortization of employee benefit plan liability, net of tax	146	97	438	293
Total Comprehensive Income	$ (8,166)	$ (7,323)	$ 35,092	$ 43,369