Annual report pursuant to Section 13 and 15(d)

Commitments And Contingencies (Narrative) (Details)

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Commitments And Contingencies (Narrative) (Details)
$ in Thousands
12 Months Ended
Dec. 31, 2017
USD ($)
equipment
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Dec. 31, 2013
claim
Dec. 31, 2012
claim
Dec. 31, 2010
claim
Sep. 30, 2016
USD ($)
Commitments and Contingencies [Line Items]              
Unrecorded unconditional purchase obligation $ 8,461            
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year 7,849            
Unrecorded Unconditional Purchase Obligation, Due within Two Years 612            
Total rental expense for operating leases $ 42,800 $ 35,200 $ 35,400        
U.S.-flag Harbor Tugs [Member]              
Commitments and Contingencies [Line Items]              
Unrecorded Unconditional Purchase Obligation, Maximum Quantity | equipment 2            
Number of equipment leases | equipment 8            
Pure Car/Truck Carriers [Member]              
Commitments and Contingencies [Line Items]              
Number of equipment leases | equipment 4            
Inland River Dry Cargo Barges [Member]              
Commitments and Contingencies [Line Items]              
Number of equipment leases | equipment 50            
Inland River Towboats              
Commitments and Contingencies [Line Items]              
Number of equipment leases | equipment 4            
Inland River Harbor Boats [Member]              
Commitments and Contingencies [Line Items]              
Number of equipment leases | equipment 6            
U.S.-flag Petroleum and Chemical Carriers [Member]              
Commitments and Contingencies [Line Items]              
Number of equipment leases | equipment 3            
Minimum [Member]              
Commitments and Contingencies [Line Items]              
Lessee, Operating Lease, Term of Contract 1 month            
Minimum [Member] | U.S.-flag Petroleum and Chemical Carriers [Member]              
Commitments and Contingencies [Line Items]              
Sale Leaseback Transaction, Lease Terms 57            
Maximum [Member]              
Commitments and Contingencies [Line Items]              
Sale Leaseback Transaction, Lease Terms   76 84        
Lessee, Operating Lease, Term of Contract 15 years            
Maximum [Member] | Inland River Dry Cargo Barges [Member]              
Commitments and Contingencies [Line Items]              
Sale Leaseback Transaction, Lease Terms 84            
Maximum [Member] | U.S.-flag Petroleum and Chemical Carriers [Member]              
Commitments and Contingencies [Line Items]              
Sale Leaseback Transaction, Lease Terms 104            
Multi-district Litigation [Member]              
Commitments and Contingencies [Line Items]              
Loss Contingency, New Claims Filed, Number | claim           1  
Loss Contingency, Number of Plaintiffs   11          
Abney Litigation [Member]              
Commitments and Contingencies [Line Items]              
Loss Contingency, New Claims Filed, Number | claim         668    
Abood Litigation [Member]              
Commitments and Contingencies [Line Items]              
Loss Contingency, New Claims Filed, Number | claim       174      
Shipping Services [Member]              
Commitments and Contingencies [Line Items]              
Unrecorded unconditional purchase obligation $ 5,400            
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year 5,400            
Unrecorded Unconditional Purchase Obligation, Due within Two Years 0            
Inland River Services [Member]              
Commitments and Contingencies [Line Items]              
Unrecorded unconditional purchase obligation 3,061            
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year 2,449            
Unrecorded Unconditional Purchase Obligation, Due within Two Years $ 612            
American Maritime Officers Pension Plan [Member] | Pension Plan              
Commitments and Contingencies [Line Items]              
Multiemployer Plans, Withdrawal Obligation             $ 28,600