Capital leases (Details 2) - USD ($)	Mar. 31, 2016	Dec. 31, 2015
Capital Leased Assets [Line Items]
Capital Leased Assets, Gross	$ 37,083,985	$ 37,083,985
Vessels [Member]
Capital Leased Assets [Line Items]
Capital Leased Assets, Gross	$ 37,083,985	$ 37,083,985

Amount before accumulated depreciation of leased 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 840
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6455314&loc=d3e45014-112735

Name:	us-gaap_CapitalLeasedAssetsGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant