Income Taxes (Schedule Of Deferred Tax Assets And Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Income Taxes [Abstract]
Net operating loss carryforward	$ 13,958	$ 15,018
Credit carryforward	769	1,729
Accruals	29,002	24,693
Allowance for doubtful accounts	1,329	878
Inventories	7,321	6,893
Other	5,900	6,119
Deferred taxes assets-total	58,279	55,330
Property, plant and equipment	(344,535)	(328,635)
Turnaround costs	(11,073)	(13,091)
Other	(914)	(795)
Deferred tax liabilities - total	(356,522)	(342,521)
Valuation allowance	(12,937)	(11,039)
Total net deferred tax liabilities	(311,180)	(298,230)
Balance sheet classifications
Current deferred tax asset	19,611	17,288
Deferred tax liability	(330,791)	(315,518)
Total net deferred tax liabilities	$ (311,180)	$ (298,230)