Summary Of Significant Accounting Policies (Estimated Useful Lives of Vessels, Property and Other Equipment) (Details)	12 Months Ended
	Dec. 31, 2015
Coal Carrier [Member] | Jones Act [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	15 years
Bulk Carriers [Member] | Jones Act [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	25 years
Bulk Carriers [Member] | Dry Bulk Carriers [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	25 years
Harbor Tug [Member] | Jones Act [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	20 years
ATB Barge And Tug Units [Member] | Minimum [Member] | Jones Act [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	9 years
ATB Barge And Tug Units [Member] | Maximum [Member] | Jones Act [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	30 years
Integrated Barge and Tug Unit [Member] | Minimum [Member] | Jones Act [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	9 years
Integrated Barge and Tug Unit [Member] | Maximum [Member] | Jones Act [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	30 years
Pure Car Truck Carriers [Member] | Minimum [Member] | Pure Car Truck Carriers [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	20 years
Pure Car Truck Carriers [Member] | Maximum [Member] | Pure Car Truck Carriers [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	25 years
Special Purpose vessels [Member] | Rail Ferry [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	25 years
Special Purpose vessels [Member] | Specialty Contracts [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	25 years
Leasehold Improvements [Member] | Minimum [Member] | Other [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	10 years
Leasehold Improvements [Member] | Maximum [Member] | Other [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	20 years
Other Equipment [Member] | Minimum [Member] | Other [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	3 years
Other Equipment [Member] | Maximum [Member] | Other [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	12 years
Furniture And Equipment [Member] | Minimum [Member] | Other [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	3 years
Furniture And Equipment [Member] | Maximum [Member] | Other [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	10 years