Basis of Presentation and Accounting Policies Property and Equipment (Details) $ in Millions	6 Months Ended
	Jun. 30, 2016 USD ($)
Property, Plant and Equipment [Line Items]
Capitalized Interest Costs, Including Allowance for Funds Used During Construction	$ 9.9
Offshore Support Vessels [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	20 years
Wind Farm Utility Vessel [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	10 years
Inland River Dry Cargo Barges [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	20 years
Inland River Liquid Tank Barges [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	25 years
Inland River Towboats [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	25 years
U.S.-flag Product Tankers [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	25 years
R O R O Vessels [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	20 years
Harbor and Offshore Tugs [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	25 years
Ocean Liquid Tank Barge [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	25 years
Terminal And Manufacturing Facilities [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	20 years