Income Taxes (Schedule Of Deferred Tax Assets And Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Income Tax Expense (Benefit) [Abstract]
Net operating loss carryforward	$ 11,922	$ 13,958
Credit carryforward	782	769
Accruals	32,486	29,002
Allowance for doubtful accounts	1,540	1,329
Inventories	7,831	7,321
Other	4,704	5,900
Deferred taxes assets,total	59,265	58,279
Property, plant and equipment	(340,237)	(344,535)
Turnaround costs	(10,858)	(11,073)
Other	(228)	(914)
Deferred tax liabilities-total	(351,323)	(356,522)
Valuation allowance	(11,927)	(12,937)
Total net deferred tax liabilities	(303,985)	(311,180)
Balance sheet classifications
Current deferred tax asset	22,305	19,611
Deferred tax liability	(326,290)	(330,791)
Total net deferred tax liabilities	$ (303,985)	$ (311,180)