Address commissions expensed by third parties.

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Voyage Expenses consisting of port, canal and bunker expenses and commission costs that are incurred on time-charter and voyage-charter arrangements. Commissions are paid directly to brokers by the company.

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No definition available.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

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No definition available.

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Amount of the effect of a change in accounting principle on operating profit or loss.

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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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Significant Accounting Policies (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Adoption of New Accounting Standards [Abstract]
Adoption of revenue recognition accounting policy adjustment			$ 1,301
Vessel revenue	$ 39,533	$ 32,947
Voyage expenses	17,732	16,629
Commissions	1,391	$ 1,253
Accumulated Deficit [Member]
Adoption of New Accounting Standards [Abstract]
Adoption of revenue recognition accounting policy adjustment			$ 1,301
Calculated under Revenue Guidance in Effect before ASC 606 [Member]
Adoption of New Accounting Standards [Abstract]
Vessel revenue	40,923
Voyage expenses	18,220
Commissions	1,444
Total net effect	$ 849
Revenues [Member] \| Customer Concentration Risk [Member]
Revenue [Abstract]
Concentration risk percentage	66.00%	55.00%
Revenues [Member] \| Customer Concentration Risk [Member] \| Customer A [Member]
Revenue [Abstract]
Concentration risk percentage	27.00%	10.00%
Revenues [Member] \| Customer Concentration Risk [Member] \| Customer B [Member]
Revenue [Abstract]
Concentration risk percentage	16.00%	14.00%
Revenues [Member] \| Customer Concentration Risk [Member] \| Customer C [Member]
Revenue [Abstract]
Concentration risk percentage	12.00%	0.00%
Revenues [Member] \| Customer Concentration Risk [Member] \| Customer D [Member]
Revenue [Abstract]
Concentration risk percentage	11.00%	0.00%
Revenues [Member] \| Customer Concentration Risk [Member] \| Customer E [Member]
Revenue [Abstract]
Concentration risk percentage	0.00%	19.00%
Revenues [Member] \| Customer Concentration Risk [Member] \| Customer F [Member]
Revenue [Abstract]
Concentration risk percentage	0.00%	12.00%
ASU 2014-09 [Member] \| Accumulated Deficit [Member]
Adoption of New Accounting Standards [Abstract]
Adoption of revenue recognition accounting policy adjustment	$ (1,301)