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Period referring customer relationship maintained by some of the manufacturing and refining customers.

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Number of single customers who account for more than 10 percent of segment revenues.

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Percentage of costal revenue from movement of products under term contracts.

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Percentage of inland revenue from movement of products under term contracts.

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Number of eastern states covered as an authorized distributor.

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Relationship term maintained by entity with customers.

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Term of the guarantee or each group of financial instruments used to support performance by the company and its subsidiaries in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248

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Contingencies and Commitments, Certain Significant Risks and Uncertainties (Details) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2016 USD ($)	Sep. 30, 2016	Dec. 31, 2016 USD ($) State Customers	Dec. 31, 2015 Customers	Dec. 31, 2014 Customers
Guaranties [Abstract]
Issued guaranties	$ 13,983		$ 13,983
Guarantor obligations, expiration period			3 years
Performance Bonds [Member]
Guaranties [Abstract]
Issued guaranties	$ 10,184		$ 10,184
Marine Transportation [Member]
Certain Significant Risks and Uncertainties [Abstract]
Percentage of inland revenue	75.00%	80.00%
Marine Transportation [Member] \| Minimum [Member]
Certain Significant Risks and Uncertainties [Abstract]
Range of renewal options under term contracts			1 year
Marine Transportation [Member] \| Maximum [Member]
Certain Significant Risks and Uncertainties [Abstract]
Range of renewal options under term contracts			5 years
Marine Transportation [Member] \| Customers [Member]
Certain Significant Risks and Uncertainties [Abstract]
Percentage of costal revenue			80.00%
Customer relationship period			40 years
Number of single customers accounting more than 10% of segment revenue \| Customers			0	0	0
Diesel Engine Services [Member]
Certain Significant Risks and Uncertainties [Abstract]
Diesel engine services segment's relationship			51 years
Diesel Engine Services [Member] \| Eastern States [Member]
Certain Significant Risks and Uncertainties [Abstract]
Segment operating as authorized distributors \| State			17
Diesel Engine Services [Member] \| Western States [Member]
Certain Significant Risks and Uncertainties [Abstract]
Segment operating as authorized distributors \| State			9
Diesel Engine Services [Member] \| Customers [Member]
Certain Significant Risks and Uncertainties [Abstract]
Number of single customers accounting more than 10% of segment revenue \| Customers			0	0	0
Letters Of Credit [Member]
Guaranties [Abstract]
Issued guaranties	$ 3,799		$ 3,799