Vessels, detail (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Movement in Property, Plant and Equipment [Roll Forward]
Vessels' cost, beginning balance	$ 284,108us-gaap_PropertyPlantAndEquipmentGross	$ 280,812us-gaap_PropertyPlantAndEquipmentGross
Acquisitions and other vessel's costs	60,379	107,864
Vessels' disposals	(11,409)	(62,245)
Impairment charges	0us-gaap_AssetImpairmentCharges	(42,323)us-gaap_AssetImpairmentCharges	0us-gaap_AssetImpairmentCharges
Vessels' cost, ending balance	333,078us-gaap_PropertyPlantAndEquipmentGross	284,108us-gaap_PropertyPlantAndEquipmentGross	280,812us-gaap_PropertyPlantAndEquipmentGross
Movement in Accumulated Depreciation, Depletion and Amortization, Property, Plant and Equipment [Roll Forward]
Accumulated depreciation, beginning balance	(18,736)	(19,867)
Accumulated depreciation, vessels' disposals	1,929	12,101
Depreciation for the period	(10,177)us-gaap_Depreciation	(10,970)us-gaap_Depreciation
Accumulated depreciation, ending balance	(26,984)	(18,736)	(19,867)
Property, Plant and Equipment, Net, by Type [Abstract]
Vessels' net book value, beginning balance	265,372us-gaap_PropertyPlantAndEquipmentNet	260,945us-gaap_PropertyPlantAndEquipmentNet
Vessel's net book value, ending balance	$ 306,094us-gaap_PropertyPlantAndEquipmentNet	$ 265,372us-gaap_PropertyPlantAndEquipmentNet	$ 260,945us-gaap_PropertyPlantAndEquipmentNet

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.14)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher SEC

-Name Regulation S-X (SX)

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The decrease in accumulated depreciation, depletion and amortization (relating to property, plant and equipment) as a result of sales or disposals of property, plant and equipment during the period.

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- Definition

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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- Definition

Amount of acquisition of long-lived, physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

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Amount of divestiture of long-lived, physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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