Accounts Receivable and Inventory (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	$ 29,217	$ 83,227
Crude oil inventories	17,800	15,200
Supplies	1,300	2,100
Oil inventory impairment	2,633	0	$ 0
Trade Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	26,924	80,058
Other Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	$ 2,293	$ 3,169