Annual report pursuant to Section 13 and 15(d)

Commitments And Contingencies (Capital Commitments and Narrative) (Details)

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Commitments And Contingencies (Capital Commitments and Narrative) (Details)
$ in Thousands
Feb. 28, 2020
USD ($)
claim
equipment
Oct. 16, 2019
claim
Aug. 02, 2016
claim
Feb. 16, 2016
claim
Jan. 10, 2020
claim
Dec. 31, 2019
USD ($)
equipment
Commitments and Contingencies [Line Items]            
Unrecorded unconditional purchase obligation, due in next twelve months           $ 28,639
Unrecorded unconditional purchase obligation, due within two years           30,965
Unrecorded Unconditional Purchase Obligation, Due within Three Years           2,636
Unrecorded unconditional purchase obligation           62,240
Deepwater Horizon Oil Spill Multi District Litigation            
Commitments and Contingencies [Line Items]            
Loss Contingency, Claims Dismissed, Number | claim     11 11    
BP counter claims ORM and NRC            
Commitments and Contingencies [Line Items]            
Loss contingency, new claims filed | claim   4        
BP counterclaims ORM's insurer            
Commitments and Contingencies [Line Items]            
Loss contingency, new claims filed | claim   2        
Subsequent Event            
Commitments and Contingencies [Line Items]            
Unrecorded unconditional purchase obligation $ 2,500          
Subsequent Event | BELO/ORM            
Commitments and Contingencies [Line Items]            
Loss Contingency, Claims Dismissed, Number | claim 450          
Loss contingency, new claims filed | claim 2,380          
Subsequent Event | BELO/NRC            
Commitments and Contingencies [Line Items]            
Loss Contingency, Claims Dismissed, Number | claim 35          
Loss contingency, new claims filed | claim 230          
Subsequent Event | BP counter claims ORM and NRC            
Commitments and Contingencies [Line Items]            
Loss contingency, pending claims | claim         3  
Ocean Services            
Commitments and Contingencies [Line Items]            
Unrecorded unconditional purchase obligation, due in next twelve months           22,394
Unrecorded unconditional purchase obligation, due within two years           30,965
Unrecorded Unconditional Purchase Obligation, Due within Three Years           2,636
Unrecorded unconditional purchase obligation           $ 55,995
Ocean Services | Harbor Tugs - U.S.-flag            
Commitments and Contingencies [Line Items]            
Number of equipment committed to purchase | equipment           4
Ocean Services | Rail ferries - Foreign-flag            
Commitments and Contingencies [Line Items]            
Number of equipment committed to purchase | equipment           2
Inland Services            
Commitments and Contingencies [Line Items]            
Unrecorded unconditional purchase obligation, due in next twelve months           $ 5,663
Unrecorded unconditional purchase obligation, due within two years           0
Unrecorded Unconditional Purchase Obligation, Due within Three Years           0
Unrecorded unconditional purchase obligation           $ 5,663
Inland Services | Inland River Dry-Cargo Barges            
Commitments and Contingencies [Line Items]            
Number of equipment committed to purchase | equipment           4
Inland Services | Inland river towboats            
Commitments and Contingencies [Line Items]            
Number of equipment committed to purchase | equipment           2
Inland Services | Subsequent Event | Inland River Dry-Cargo Barges            
Commitments and Contingencies [Line Items]            
Number of equipment committed to purchase | equipment 2          
Other            
Commitments and Contingencies [Line Items]            
Unrecorded unconditional purchase obligation, due in next twelve months           $ 582
Unrecorded unconditional purchase obligation, due within two years           0
Unrecorded Unconditional Purchase Obligation, Due within Three Years           0
Unrecorded unconditional purchase obligation           $ 582