Assets Held For Sale (Details)	3 Months Ended		6 Months Ended
	Mar. 31, 2015 item	Dec. 31, 2014 USD ($) item	Jun. 30, 2015 USD ($) item
Property, Plant and Equipment [Line Items]
Long Term Assets Held for Sale		$ 48,701,000
Short Term Assets Held for Sale		$ 6,976,000	$ 6,435,000
Handysize Vessel [Member]
Property, Plant and Equipment [Line Items]
Number of vessels held for sale | item		3
Long Term Assets Held for Sale		$ 48,700,000
Number of vessels sold | item	1
Number of vessels held in use | item			2
Impairment loss			$ 1,800,000
Jones Act Tug-Barge [Member]
Property, Plant and Equipment [Line Items]
Number of vessels held for sale | item		1
Tug-Barge Unit And Inventory Related To Handysize Vessels [Member]
Property, Plant and Equipment [Line Items]
Short Term Assets Held for Sale		$ 7,000,000
Depreciation expense			0
Tug-Barge Unit [Member]
Property, Plant and Equipment [Line Items]
Short Term Assets Held for Sale			$ 6,400,000