Impairment Loss (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($)
Property, Plant and Equipment [Line Items]
Impairment charge	$ 1,934
Impairment charges of assets held for sale	564	[1]
Inactive Tug [Member] | Jones Act [Member]
Property, Plant and Equipment [Line Items]
Impairment charges of assets held for sale	400
Inactive Barge [Member] | Jones Act [Member]
Property, Plant and Equipment [Line Items]
Impairment charge	900
Inactive Harbor Tug [Member] | Jones Act [Member]
Property, Plant and Equipment [Line Items]
Impairment charges of assets held for sale	100
Belt Self-Unloading Bulk Carrier [Member] | Jones Act [Member]
Property, Plant and Equipment [Line Items]
Impairment charges of assets held for sale	400
New Orleans Office Building [Member]
Property, Plant and Equipment [Line Items]
Impairment charges of assets held for sale	$ 100

[1] Refers to our Jones Act inactive tug and our New Orleans office building included in current assets held for sale at March 31, 2016.