Vessels (Details Textual) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Property, Plant and Equipment [Line Items]
Gain (Loss) on disposition of property	$ 1,073us-gaap_GainLossOnDispositionOfAssets	$ 1,477us-gaap_GainLossOnDispositionOfAssets
Us Flag [Member]
Property, Plant and Equipment [Line Items]
Gain (Loss) on disposition of property	$ 0	$ 1,510

Amount of gain (loss) on sale or disposal of property, plant and equipment assets, excluding oil and gas property and timber property.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6391110&loc=d3e2941-110230

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1361-107760

Name:	us-gaap_GainLossOnDispositionOfAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration