Accounts Receivable and Inventory (Details) (USD $)	Dec. 31, 2011	Dec. 31, 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable	$ 69,362,000	$ 43,035,000
Crude oil inventories	4,700,000	3,600,000
Supplies	2,400,000	2,100,000
Trade Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable	45,922,000	34,182,000
Other Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable	$ 23,440,000	$ 8,853,000