Annual report pursuant to Section 13 and 15(d)

Nature Of Operations And Accounting Policies (Schedule Of Property And Equipment By Major Classes) (Details)

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Nature Of Operations And Accounting Policies (Schedule Of Property And Equipment By Major Classes) (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Property, Plant and Equipment [Line Items]    
Property, Plant and Equipment, Gross $ 1,351,741 $ 1,178,556
Accumulated Depreciation (502,544) (444,559)
Net property and equipment 877,925 980,007
Property, Plant and Equipment, Other, Gross 849,197 733,997
Shipping Services [Member]    
Property, Plant and Equipment [Line Items]    
Property, Plant and Equipment, Gross 875,090 727,602
Accumulated Depreciation (299,528) (258,004)
Net property and equipment 575,562 469,598
Shipping Services [Member] | U.S.-flag Petroleum and Chemical Carriers [Member]    
Property, Plant and Equipment [Line Items]    
Property, Plant and Equipment, Gross 652,985 546,019
Accumulated Depreciation (215,057) (189,536)
Net property and equipment 437,928 356,483
Shipping Services [Member] | U.S.-flag Harbor Tugs [Member]    
Property, Plant and Equipment [Line Items]    
Property, Plant and Equipment, Gross 84,155 72,877
Accumulated Depreciation (38,984) (34,606)
Net property and equipment 45,171 38,271
Shipping Services [Member] | Foreign-flag Harbor Tugs [Member]    
Property, Plant and Equipment [Line Items]    
Property, Plant and Equipment, Gross 45,338 29,689
Accumulated Depreciation (11,575) (9,480)
Net property and equipment 33,763 20,209
Shipping Services [Member] | Ocean Liquid Tank Barge [Member]    
Property, Plant and Equipment [Line Items]    
Property, Plant and Equipment, Gross 39,238 39,238
Accumulated Depreciation (13,126) (11,604)
Net property and equipment 26,112 27,634
Shipping Services [Member] | Short-sea Container\RORO Vessels [Member]    
Property, Plant and Equipment [Line Items]    
Property, Plant and Equipment, Gross 20,954 20,954
Accumulated Depreciation (8,178) (6,774)
Net property and equipment 12,776 14,180
Shipping Services [Member] | U.S.-flag Dry bulk Carrier [Member]    
Property, Plant and Equipment [Line Items]    
Property, Plant and Equipment, Gross 13,000  
Accumulated Depreciation (4,733)  
Net property and equipment 8,267  
Shipping Services [Member] | Property, Plant and Equipment, Other Types [Member]    
Property, Plant and Equipment [Line Items]    
Property, Plant and Equipment, Gross 19,420 18,825
Accumulated Depreciation (7,875) (6,004)
Net property and equipment 11,545 12,821
Inland River Services [Member]    
Property, Plant and Equipment [Line Items]    
Property, Plant and Equipment, Gross 445,293 419,714
Accumulated Depreciation (181,573) (167,127)
Net property and equipment 263,720 252,587
Inland River Services [Member] | Property, Plant and Equipment, Other Types [Member]    
Property, Plant and Equipment [Line Items]    
Property, Plant and Equipment, Gross 20,470 18,145
Accumulated Depreciation (8,254) (6,658)
Net property and equipment 12,216 11,487
Inland River Services [Member] | Inland River Dry Cargo Barges [Member]    
Property, Plant and Equipment [Line Items]    
Property, Plant and Equipment, Gross 233,734 246,237
Accumulated Depreciation (101,087) (97,602)
Net property and equipment 132,647 148,635
Inland River Services [Member] | Inland River Specialty Barges [Member]    
Property, Plant and Equipment [Line Items]    
Property, Plant and Equipment, Gross 10,648 12,292
Accumulated Depreciation (4,928) (4,869)
Net property and equipment 5,720 7,423
Inland River Services [Member] | Inland River Liquid Tank Barges [Member]    
Property, Plant and Equipment [Line Items]    
Property, Plant and Equipment, Gross 21,802 16,114
Accumulated Depreciation (2,684) (1,982)
Net property and equipment 19,118 14,132
Inland River Services [Member] | Inland River Towboats    
Property, Plant and Equipment [Line Items]    
Property, Plant and Equipment, Gross 44,555 14,675
Accumulated Depreciation (1,765) (1,320)
Net property and equipment 42,790 13,355
Inland River Services [Member] | Inland River Harbor Boats [Member]    
Property, Plant and Equipment [Line Items]    
Property, Plant and Equipment, Gross 18,158 17,338
Accumulated Depreciation (6,956) (5,715)
Net property and equipment 11,202 11,623
Inland River Services [Member] | Terminal And Manufacturing Facilities [Member]    
Property, Plant and Equipment [Line Items]    
Property, Plant and Equipment, Gross 95,926 94,913
Accumulated Depreciation (55,899) (48,981)
Net property and equipment 40,027 45,932
Witt O'Brien's LLC [Member] | Property, Plant and Equipment, Other Types [Member]    
Property, Plant and Equipment [Line Items]    
Property, Plant and Equipment, Gross 1,227 1,559
Accumulated Depreciation (938) (1,244)
Net property and equipment 289 315
Corporate And Eliminations [Member] | Property, Plant and Equipment, Other Types [Member]    
Property, Plant and Equipment [Line Items]    
Property, Plant and Equipment, Gross 30,131 29,681
Accumulated Depreciation (20,505) (18,184)
Net property and equipment $ 9,626 $ 11,497