Schedule II - Valuation And Qualifying Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Other Assets - Other Notes And Accounts Receivable [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year			$ 109		$ 225
Additions (Reductions) Charged to Costs and Expenses	17				(17)
Charged to Other Accounts
Deductions			109	[1]	99	[1]
Balance at End of Year	17				109
Current Assets - Supplies And Inventory [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	12,701		13,406		12,760
Additions (Reductions) Charged to Costs and Expenses	1,755		1,962		1,302
Charged to Other Accounts
Deductions	1,349	[1]	2,667	[1]	656	[1]
Balance at End of Year	13,107		12,701		13,406
Deferred Income Taxes [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	737		1,120		395
Additions (Reductions) Charged to Costs and Expenses	2,416		(383)		725
Charged to Other Accounts
Deductions	322	[1]				[1]
Balance at End of Year	$ 2,831		$ 737		$ 1,120

[1] Reserves utilized, unless otherwise indicated.