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Significant Accounting Policies-Addittional Information (Details) - USD ($) $ / shares in Units, $ in Thousands | 6 Months Ended | 12 Months Ended
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Jun. 30, 2015 | Dec. 31, 2014
Significant Accounting Policies_Vessels, Net [Abstract] |  |
Estimated scrap rate | $0.300 per lightweight ton | Approximately $0.250 per light weight ton
Estimated useful life | 30 years |
Decrease in depreciation expense | $ 2,692 |
Increase in net income | $ 2,692 |
Increase in per common share, basic and diluted | $ 0.04 |

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- Definition Describes the periods of time over which an entity anticipates to receive utility from its property, plant and equipment (that is, the periods of time over which an entity allocates the initial cost of its property, plant and equipment). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=51655414&loc=d3e18780-107790 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 35 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=51661791&loc=d3e1205-110223 + Details
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