Quarterly report pursuant to Section 13 or 15(d)

Segment Information (Operating Results, Capital Expenditures And Assets By Reportable Segments) (Details)

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Segment Information (Operating Results, Capital Expenditures And Assets By Reportable Segments) (Details) - USD ($)
3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Segment Reporting Information [Line Items]      
Operating Revenues $ 184,824,000 $ 136,319,000  
Costs and Expenses [Abstract]      
Administrative and general 25,795,000 22,878,000  
Depreciation and amortization 19,609,000 16,719,000  
Total costs and expenses 177,181,000 132,714,000  
Gains (Losses) on Asset Dispositions and Impairments, Net 7,045,000 (188,000)  
Operating Income (Loss) 14,688,000 3,417,000  
Other Income and Expenses [Abstract]      
Gain (Loss) on Derivative Instruments, Net, Pretax 0 2,830,000  
Foreign currency gains (losses), net 1,690,000 1,399,000  
Other, net 283,000 (420,000)  
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax (837,000) 108,000  
Loss Before Taxes and Equity Earnings 6,114,000 19,892,000  
Capital Expenditures 9,542,000 66,810,000  
Property, Plant and Equipment, Gross 1,354,989,000   $ 1,351,741,000
Accumulated depreciation 510,418,000   502,544,000
Construction in progress 15,528,000   28,728,000
Net property and equipment 860,099,000   877,925,000
Inventories 3,821,000   4,377,000
Goodwill 32,807,000   32,761,000
Intangible Assets, Net 28,072,000   28,106,000
Disposal Group, Including Discontinued Operation, Assets   1,174,908,000  
Total assets 1,612,473,000 2,954,978,000 $ 1,613,336,000
Ocean Services [Member]      
Segment Reporting Information [Line Items]      
Operating Revenues 102,384,000 67,639,000  
Inland Services [Member]      
Segment Reporting Information [Line Items]      
Operating Revenues 55,921,000 60,574,000  
Witt O'Brien's LLC [Member]      
Segment Reporting Information [Line Items]      
Operating Revenues 26,432,000 8,008,000  
Other Segments [Member]      
Segment Reporting Information [Line Items]      
Operating Revenues 116,000 116,000  
Corporate And Eliminations [Member]      
Segment Reporting Information [Line Items]      
Operating Revenues (29,000) (18,000)  
Operating Segments [Member]      
Segment Reporting Information [Line Items]      
Operating Revenues 184,824,000 136,319,000  
Costs and Expenses [Abstract]      
Operating Expenses 131,777,000 93,117,000  
Administrative and general 25,795,000 22,878,000  
Depreciation and amortization 19,609,000 16,719,000  
Total costs and expenses 177,181,000 132,714,000  
Gains (Losses) on Asset Dispositions and Impairments, Net 7,045,000 (188,000)  
Operating Income (Loss) 14,688,000 3,417,000  
Other Income and Expenses [Abstract]      
Gain (Loss) on Derivative Instruments, Net, Pretax   2,830,000  
Foreign currency gains (losses), net 1,690,000 1,399,000  
Other, net 283,000 (420,000)  
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax (837,000) 108,000  
Capital Expenditures 9,542,000 66,810,000  
Property, Plant and Equipment, Gross 1,354,989,000    
Accumulated depreciation 510,418,000 460,623,000  
Property, Plant and Equipment, Net In Service 844,571,000    
Construction in progress 15,528,000    
Net property and equipment 860,099,000 1,015,878,000  
Investments, at Equity, and Advances to 50% or Less Owned Companies 170,305,000 182,395,000  
Inventories 3,821,000 3,051,000  
Goodwill 32,807,000 32,787,000  
Intangible Assets, Net 28,072,000 19,519,000  
Other Current And Long-Term Assets, Excluding Cash And Near Cash Assets 166,112,000 154,759,000  
Operating Segments [Member] | Ocean Services [Member]      
Segment Reporting Information [Line Items]      
Operating Revenues 102,384,000 67,639,000  
Costs and Expenses [Abstract]      
Operating Expenses 65,333,000 37,354,000  
Administrative and general 10,549,000 7,088,000  
Depreciation and amortization 12,645,000 9,161,000  
Total costs and expenses 88,527,000 53,603,000  
Gains (Losses) on Asset Dispositions and Impairments, Net 1,883,000 (421,000)  
Operating Income (Loss) 15,740,000 13,615,000  
Other Income and Expenses [Abstract]      
Gain (Loss) on Derivative Instruments, Net, Pretax   0  
Foreign currency gains (losses), net (51,000) (5,000)  
Other, net 283,000 (362,000)  
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax 315,000 1,036,000  
Segment Profit (Loss) 16,287,000 14,284,000  
Capital Expenditures 7,516,000 52,619,000  
Property, Plant and Equipment, Gross 890,040,000 872,285,000  
Accumulated depreciation 309,371,000 267,163,000  
Property, Plant and Equipment, Net In Service 580,669,000 605,122,000  
Construction in progress 11,707,000 127,734,000  
Net property and equipment 592,376,000 732,856,000  
Investments, at Equity, and Advances to 50% or Less Owned Companies 53,620,000 54,514,000  
Inventories 1,732,000 1,086,000  
Goodwill 1,852,000 1,852,000  
Intangible Assets, Net 9,961,000 0  
Other Current And Long-Term Assets, Excluding Cash And Near Cash Assets 57,593,000 23,999,000  
Total assets 717,134,000 814,307,000  
Operating Segments [Member] | Inland Services [Member]      
Segment Reporting Information [Line Items]      
Operating Revenues 55,921,000 60,574,000  
Costs and Expenses [Abstract]      
Operating Expenses 48,181,000 50,474,000  
Administrative and general 3,312,000 3,792,000  
Depreciation and amortization 6,234,000 6,592,000  
Total costs and expenses 57,727,000 60,858,000  
Gains (Losses) on Asset Dispositions and Impairments, Net 5,162,000 233,000  
Operating Income (Loss) 3,356,000 (51,000)  
Other Income and Expenses [Abstract]      
Gain (Loss) on Derivative Instruments, Net, Pretax   0  
Foreign currency gains (losses), net 1,703,000 1,368,000  
Other, net 0 0  
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax (2,454,000) (2,378,000)  
Segment Profit (Loss) 2,605,000 (1,061,000)  
Capital Expenditures 1,899,000 12,819,000  
Property, Plant and Equipment, Gross 433,590,000 433,382,000  
Accumulated depreciation 179,152,000 173,249,000  
Property, Plant and Equipment, Net In Service 254,438,000 260,133,000  
Construction in progress 3,821,000 12,014,000  
Net property and equipment 258,259,000 272,147,000  
Investments, at Equity, and Advances to 50% or Less Owned Companies 64,744,000 68,193,000  
Inventories 2,039,000 1,812,000  
Goodwill 2,449,000 2,429,000  
Intangible Assets, Net 10,112,000 11,642,000  
Other Current And Long-Term Assets, Excluding Cash And Near Cash Assets 54,531,000 57,575,000  
Total assets 392,134,000 413,798,000  
Operating Segments [Member] | Witt O'Brien's LLC [Member]      
Segment Reporting Information [Line Items]      
Operating Revenues 26,403,000 7,990,000  
Costs and Expenses [Abstract]      
Operating Expenses 18,306,000 5,372,000  
Administrative and general 5,367,000 3,219,000  
Depreciation and amortization 301,000 202,000  
Total costs and expenses 23,974,000 8,793,000  
Gains (Losses) on Asset Dispositions and Impairments, Net 0 0  
Operating Income (Loss) 2,458,000 (785,000)  
Other Income and Expenses [Abstract]      
Gain (Loss) on Derivative Instruments, Net, Pretax   0  
Foreign currency gains (losses), net 2,000 10,000  
Other, net 0 0  
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax 135,000 157,000  
Segment Profit (Loss) 2,595,000 (618,000)  
Capital Expenditures 0 35,000  
Property, Plant and Equipment, Gross 1,227,000 1,559,000  
Accumulated depreciation 961,000 1,262,000  
Property, Plant and Equipment, Net In Service 266,000 297,000  
Construction in progress 0 34,000  
Net property and equipment 266,000 331,000  
Investments, at Equity, and Advances to 50% or Less Owned Companies 734,000 758,000  
Inventories 50,000 153,000  
Goodwill 28,506,000 28,506,000  
Intangible Assets, Net 7,999,000 7,877,000  
Other Current And Long-Term Assets, Excluding Cash And Near Cash Assets 43,563,000 17,665,000  
Total assets 81,118,000 55,290,000  
Operating Segments [Member] | Other Segments [Member]      
Segment Reporting Information [Line Items]      
Operating Revenues 116,000 116,000  
Costs and Expenses [Abstract]      
Operating Expenses 0 0  
Administrative and general 186,000 154,000  
Depreciation and amortization 0 0  
Total costs and expenses 186,000 154,000  
Gains (Losses) on Asset Dispositions and Impairments, Net 0 0  
Operating Income (Loss) (70,000) (38,000)  
Other Income and Expenses [Abstract]      
Gain (Loss) on Derivative Instruments, Net, Pretax   0  
Foreign currency gains (losses), net 0 0  
Other, net 0 (300,000)  
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax 1,167,000 1,293,000  
Segment Profit (Loss) 1,097,000 955,000  
Capital Expenditures 0 0  
Property, Plant and Equipment, Gross 0 0  
Accumulated depreciation 0 0  
Property, Plant and Equipment, Net In Service 0 0  
Construction in progress 0 0  
Net property and equipment 0 0  
Investments, at Equity, and Advances to 50% or Less Owned Companies 51,207,000 58,930,000  
Inventories 0 0  
Goodwill 0 0  
Intangible Assets, Net 0 0  
Other Current And Long-Term Assets, Excluding Cash And Near Cash Assets 1,770,000 11,988,000  
Total assets 52,977,000 70,918,000  
Operating Segments [Member] | Corporate And Eliminations [Member]      
Segment Reporting Information [Line Items]      
Operating Revenues 0 0  
Costs and Expenses [Abstract]      
Operating Expenses (43,000) (83,000)  
Administrative and general 6,381,000 8,625,000  
Depreciation and amortization 429,000 764,000  
Total costs and expenses 6,767,000 9,306,000  
Gains (Losses) on Asset Dispositions and Impairments, Net 0 0  
Operating Income (Loss) (6,796,000) (9,324,000)  
Other Income and Expenses [Abstract]      
Gain (Loss) on Derivative Instruments, Net, Pretax   2,830,000  
Foreign currency gains (losses), net 36,000 26,000  
Other, net 0 242,000  
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax 0 0  
Capital Expenditures 127,000 1,337,000  
Property, Plant and Equipment, Gross 30,132,000 29,493,000  
Accumulated depreciation 20,934,000 18,949,000  
Property, Plant and Equipment, Net In Service 9,198,000 10,544,000  
Construction in progress 0 0  
Net property and equipment 9,198,000 10,544,000  
Investments, at Equity, and Advances to 50% or Less Owned Companies 0 0  
Inventories 0 0  
Goodwill 0 0  
Intangible Assets, Net 0 0  
Other Current And Long-Term Assets, Excluding Cash And Near Cash Assets 8,655,000 43,532,000  
Intersegment Eliminations [Member]      
Segment Reporting Information [Line Items]      
Operating Revenues 0 0  
Intersegment Eliminations [Member] | Ocean Services [Member]      
Segment Reporting Information [Line Items]      
Operating Revenues 0 0  
Intersegment Eliminations [Member] | Inland Services [Member]      
Segment Reporting Information [Line Items]      
Operating Revenues 0 0  
Intersegment Eliminations [Member] | Witt O'Brien's LLC [Member]      
Segment Reporting Information [Line Items]      
Operating Revenues (29,000) 18,000  
Intersegment Eliminations [Member] | Other Segments [Member]      
Segment Reporting Information [Line Items]      
Operating Revenues 0 0  
Intersegment Eliminations [Member] | Corporate And Eliminations [Member]      
Segment Reporting Information [Line Items]      
Operating Revenues 29,000 (18,000)  
Segment Reconciling Items [Member]      
Other Income and Expenses [Abstract]      
Other Income (Expense) not included in Segment Profit (Loss) 10,547,000 (12,666,000)  
Less Equity Earnings included in Segment Profit (Loss) 837,000 (108,000)  
Cash And Near Cash Assets $ 351,257,000 $ 371,681,000