Transactions with Related Parties (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Poseidon Oil Pipeline Company
Related Party Transaction [Line Items]
Due from related parties	$ 1,800		$ 2,200
Management Fees Revenue	2,200
Revenue from Related Parties	3,200	$ 3,022
Related Party Transaction, Expenses from Transactions with Related Party	249	241
ANSAC
Related Party Transaction [Line Items]
Due from related parties	71,276		$ 74,490
Revenue from Related Parties	90,796	0
Related Party Transaction, Expenses from Transactions with Related Party	$ 1,778	$ 0

For an unclassified balance sheet, amounts due from related parties including affiliates, employees, joint ventures, officers and stockholders, immediate families thereof, and pension funds.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-SubTopic 210
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
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