Equipment Acquisitions, Dispositions and Depreciation and Impairment Policies (Useful Life) (Details)	6 Months Ended
	Jun. 30, 2013
Offshore Support Vessels [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	20 years
Wind Farm Utility Vessel [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	10 years
Inland River Dry Cargo And Deck Barges [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	20 years
Inland River Liquid Tank Barges [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	25 years
Inland River Towboats [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	25 years
U S Flag Tankers [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	25 years
R O R O Vessels [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	20 years	[1]
Harbor And Offshore Tugs [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	25 years
Ocean Liquid Tank Barge [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	25 years
Terminal And Manufacturing Facilities [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	20 years

[1] Roll on/Roll off ("RORO").