Annual report pursuant to Section 13 and 15(d)

Equipment Acquisitions And Dispositions (Major Equipment Additions) (Details)

v3.20.4
Equipment Acquisitions And Dispositions (Major Equipment Additions) (Details)
12 Months Ended
Dec. 31, 2020
equipment
vessel
Dec. 31, 2019
equipment
Dec. 31, 2018
equipment
Harbor tugs - U.S.-flag      
Property, Plant and Equipment [Line Items]      
Number of equipment acquired 0 1 5
Short-sea container/RORO - Foreign-flag      
Property, Plant and Equipment [Line Items]      
Number of equipment acquired 0 0 2
Inland river dry-cargo barges      
Property, Plant and Equipment [Line Items]      
Number of equipment acquired 6 0 0
Inland river towboats      
Property, Plant and Equipment [Line Items]      
Number of equipment acquired 1 2 0
Weber Marine LLC | Harbor boats      
Property, Plant and Equipment [Line Items]      
Number of equipment acquired | vessel 8    
Weber Marine LLC | Launch support boats      
Property, Plant and Equipment [Line Items]      
Number of equipment acquired | vessel 22