Segment Information (Operating Results, Capital Expenditures And Assets By Reportable Segments) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Operating Revenues	$ 315,563,000	$ 309,225,000	$ 582,627,000	$ 607,074,000
Costs and Expenses [Abstract]
Administrative and general	34,718,000	36,301,000	70,363,000	71,292,000
Depreciation and amortization	33,783,000	33,220,000	67,331,000	62,922,000
Total costs and expenses	308,614,000	314,066,000	578,720,000	587,178,000
Gain (Loss) on Sale of Assets and Asset Impairment Charges	12,305,000	3,342,000	14,320,000	7,119,000
Operating Income (Loss)	19,254,000	(1,499,000)	18,227,000	27,015,000
Other Income and Expenses [Abstract]
Derivative gains (losses), net	(825,000)	2,554,000	(2,932,000)	(404,000)
Foreign currency gains (losses), net	(916,000)	(1,024,000)	(4,927,000)	637,000
Other Nonoperating Income (Expense)	195,000	443,000	198,000	359,000
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	7,710,000	295,000	6,841,000	7,956,000
Income from Continuing Operations Before Income Tax Expense and Equity in Earnings of 50% or Less Owned Companies	19,561,000	9,450,000	6,741,000	32,437,000
Capital Expenditures			87,931,000	99,507,000
Property, Plant and Equipment, Gross	2,212,929,000		2,212,929,000		2,238,383,000
Accumulated depreciation	806,672,000		806,672,000		763,803,000
Property, Plant and Equipment, Net In Service	1,406,257,000		1,406,257,000		1,474,580,000
Construction in Progress, Gross	133,985,000		133,985,000		110,296,000
Net property and equipment	1,540,242,000		1,540,242,000		1,584,876,000
Inventories	22,955,000		22,955,000		25,787,000
Goodwill	17,978,000		17,978,000		17,978,000
Intangible Assets, Net	14,594,000		14,594,000		15,305,000
Total assets	2,768,333,000	3,845,817,000	2,768,333,000	3,845,817,000	3,700,794,000
Offshore Marine Services [Member]
Segment Reporting Information [Line Items]
Operating Revenues	138,650,000	123,359,000	262,642,000	244,310,000
Inland River Services [Member]
Segment Reporting Information [Line Items]
Operating Revenues	46,780,000	53,302,000	96,203,000	106,792,000
Shipping Services [Member]
Segment Reporting Information [Line Items]
Operating Revenues	48,103,000	42,716,000	94,579,000	88,449,000
Ethanol and Industrial Alcohol [Member]
Segment Reporting Information [Line Items]
Operating Revenues	61,378,000	58,938,000	94,227,000	98,557,000
Other Income and Expenses [Abstract]
Sales Revenue, Goods, Net			92,700,000	96,600,000
Cost of Goods Sold			91,900,000	92,700,000
Inventory, Raw Materials	2,800,000	2,800,000	2,800,000	2,800,000
Inventory, Work in Process	2,200,000	2,400,000	2,200,000	2,400,000
Other Segments [Member]
Segment Reporting Information [Line Items]
Operating Revenues	20,652,000	30,910,000	34,976,000	68,966,000
Corporate And Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues	0	0	0	0
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating Revenues	315,563,000	309,225,000	582,627,000	607,074,000
Costs and Expenses [Abstract]
Operating Expenses	240,113,000	244,545,000	441,026,000	452,964,000
Administrative and general	34,718,000	36,301,000	70,363,000	71,292,000
Depreciation and amortization	33,783,000	33,220,000	67,331,000	62,922,000
Total costs and expenses	308,614,000	314,066,000	578,720,000	587,178,000
Gain (Loss) on Sale of Assets and Asset Impairment Charges	12,305,000	3,342,000	14,320,000	7,119,000
Operating Income (Loss)	19,254,000	(1,499,000)	18,227,000	27,015,000
Other Income and Expenses [Abstract]
Derivative gains (losses), net	(825,000)	2,554,000	(2,932,000)	(404,000)
Foreign currency gains (losses), net	(916,000)	(1,024,000)	(4,927,000)	637,000
Other Nonoperating Income (Expense)	195,000	443,000	198,000	359,000
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	7,710,000	295,000	6,841,000	7,956,000
Capital Expenditures			87,931,000	99,507,000
Property, Plant and Equipment, Gross	2,212,929,000	2,168,106,000	2,212,929,000	2,168,106,000
Accumulated depreciation	806,672,000	714,730,000	806,672,000	714,730,000
Property, Plant and Equipment, Net In Service	1,406,257,000	1,453,376,000	1,406,257,000	1,453,376,000
Construction in Progress, Gross	133,985,000	143,100,000	133,985,000	143,100,000
Net property and equipment	1,540,242,000	1,596,476,000	1,540,242,000	1,596,476,000
Investments, at Equity, and Advances to 50% or Less Owned Companies	293,793,000	281,992,000	293,793,000	281,992,000
Inventories	22,955,000	27,248,000	22,955,000	27,248,000
Goodwill	17,978,000	56,702,000	17,978,000	56,702,000
Intangible Assets, Net	14,594,000	21,116,000	14,594,000	21,116,000
Other Current And Long-Term Assets, Excluding Cash And Near Cash Assets	289,573,000	341,501,000	289,573,000	341,501,000
Operating Segments [Member] | Offshore Marine Services [Member]
Segment Reporting Information [Line Items]
Operating Revenues	138,678,000	123,276,000	262,694,000	244,362,000
Costs and Expenses [Abstract]
Operating Expenses	97,581,000	94,084,000	187,612,000	169,424,000
Administrative and general	14,235,000	13,146,000	29,062,000	25,002,000
Depreciation and amortization	16,460,000	15,859,000	32,747,000	28,741,000
Total costs and expenses	128,276,000	123,089,000	249,421,000	223,167,000
Gain (Loss) on Sale of Assets and Asset Impairment Charges	7,895,000	624,000	10,234,000	2,469,000
Operating Income (Loss)	18,297,000	811,000	23,507,000	23,664,000
Other Income and Expenses [Abstract]
Derivative gains (losses), net	175,000	0	325,000	0
Foreign currency gains (losses), net	(833,000)	(354,000)	(4,097,000)	769,000
Other Nonoperating Income (Expense)	11,000	11,000	11,000	11,000
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	7,694,000	1,001,000	9,007,000	2,830,000
Segment Profit (Loss)	25,344,000	1,469,000	28,753,000	27,274,000
Capital Expenditures			49,764,000	64,383,000
Property, Plant and Equipment, Gross	1,151,751,000	1,075,935,000	1,151,751,000	1,075,935,000
Accumulated depreciation	439,211,000	393,813,000	439,211,000	393,813,000
Property, Plant and Equipment, Net In Service	712,540,000	682,122,000	712,540,000	682,122,000
Construction in Progress, Gross	90,847,000	107,709,000	90,847,000	107,709,000
Net property and equipment	803,387,000	789,831,000	803,387,000	789,831,000
Investments, at Equity, and Advances to 50% or Less Owned Companies	84,418,000	68,081,000	84,418,000	68,081,000
Inventories	5,885,000	5,738,000	5,885,000	5,738,000
Goodwill	13,367,000	13,367,000	13,367,000	13,367,000
Intangible Assets, Net	4,584,000	5,029,000	4,584,000	5,029,000
Other Current And Long-Term Assets, Excluding Cash And Near Cash Assets	146,551,000	148,525,000	146,551,000	148,525,000
Total assets	1,058,192,000	1,030,571,000	1,058,192,000	1,030,571,000
Operating Segments [Member] | Inland River Services [Member]
Segment Reporting Information [Line Items]
Operating Revenues	47,357,000	53,302,000	97,434,000	106,792,000
Costs and Expenses [Abstract]
Operating Expenses	35,193,000	37,463,000	71,582,000	72,646,000
Administrative and general	3,921,000	3,773,000	7,945,000	7,755,000
Depreciation and amortization	7,078,000	7,244,000	14,162,000	14,251,000
Total costs and expenses	46,192,000	48,480,000	93,689,000	94,652,000
Gain (Loss) on Sale of Assets and Asset Impairment Charges	4,296,000	858,000	4,993,000	2,785,000
Operating Income (Loss)	5,461,000	5,680,000	8,738,000	14,925,000
Other Income and Expenses [Abstract]
Derivative gains (losses), net	0	0	0	0
Foreign currency gains (losses), net	219,000	(71,000)	82,000	(93,000)
Other Nonoperating Income (Expense)	0	0	0	0
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	1,000	439,000	(2,386,000)	689,000
Segment Profit (Loss)	5,681,000	6,048,000	6,434,000	15,521,000
Capital Expenditures			9,238,000	13,108,000
Property, Plant and Equipment, Gross	466,553,000	481,045,000	466,553,000	481,045,000
Accumulated depreciation	134,235,000	116,509,000	134,235,000	116,509,000
Property, Plant and Equipment, Net In Service	332,318,000	364,536,000	332,318,000	364,536,000
Construction in Progress, Gross	17,700,000	12,790,000	17,700,000	12,790,000
Net property and equipment	350,018,000	377,326,000	350,018,000	377,326,000
Investments, at Equity, and Advances to 50% or Less Owned Companies	55,875,000	53,859,000	55,875,000	53,859,000
Inventories	2,260,000	2,038,000	2,260,000	2,038,000
Goodwill	2,759,000	4,345,000	2,759,000	4,345,000
Intangible Assets, Net	8,416,000	8,377,000	8,416,000	8,377,000
Other Current And Long-Term Assets, Excluding Cash And Near Cash Assets	37,260,000	49,890,000	37,260,000	49,890,000
Total assets	456,588,000	495,835,000	456,588,000	495,835,000
Operating Segments [Member] | Shipping Services [Member]
Segment Reporting Information [Line Items]
Operating Revenues	48,103,000	42,824,000	94,579,000	88,557,000
Costs and Expenses [Abstract]
Operating Expenses	29,554,000	28,214,000	56,168,000	55,786,000
Administrative and general	6,124,000	5,505,000	11,301,000	10,372,000
Depreciation and amortization	7,907,000	7,362,000	15,704,000	14,979,000
Total costs and expenses	43,585,000	41,081,000	83,173,000	81,137,000
Gain (Loss) on Sale of Assets and Asset Impairment Charges	114,000	1,860,000	(2,955,000)	1,860,000
Operating Income (Loss)	4,632,000	3,603,000	8,451,000	9,280,000
Other Income and Expenses [Abstract]
Derivative gains (losses), net	0	0	0	0
Foreign currency gains (losses), net	(8,000)	(4,000)	(15,000)	9,000
Other Nonoperating Income (Expense)	188,000	257,000	202,000	287,000
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	(403,000)	(774,000)	(1,908,000)	(991,000)
Segment Profit (Loss)	4,409,000	3,082,000	6,730,000	8,585,000
Capital Expenditures			27,048,000	12,921,000
Property, Plant and Equipment, Gross	517,409,000	518,258,000	517,409,000	518,258,000
Accumulated depreciation	214,372,000	188,148,000	214,372,000	188,148,000
Property, Plant and Equipment, Net In Service	303,037,000	330,110,000	303,037,000	330,110,000
Construction in Progress, Gross	22,037,000	14,065,000	22,037,000	14,065,000
Net property and equipment	325,074,000	344,175,000	325,074,000	344,175,000
Investments, at Equity, and Advances to 50% or Less Owned Companies	66,786,000	90,626,000	66,786,000	90,626,000
Inventories	1,427,000	1,288,000	1,427,000	1,288,000
Goodwill	1,852,000	1,852,000	1,852,000	1,852,000
Intangible Assets, Net	1,134,000	1,677,000	1,134,000	1,677,000
Other Current And Long-Term Assets, Excluding Cash And Near Cash Assets	16,021,000	16,410,000	16,021,000	16,410,000
Total assets	412,294,000	456,028,000	412,294,000	456,028,000
Operating Segments [Member] | Ethanol and Industrial Alcohol [Member]
Segment Reporting Information [Line Items]
Operating Revenues	61,378,000	58,938,000	94,227,000	98,557,000
Costs and Expenses [Abstract]
Operating Expenses	59,402,000	57,201,000	93,447,000	94,606,000
Administrative and general	477,000	434,000	1,138,000	859,000
Depreciation and amortization	1,489,000	1,578,000	2,978,000	2,630,000
Total costs and expenses	61,368,000	59,213,000	97,563,000	98,095,000
Gain (Loss) on Sale of Assets and Asset Impairment Charges	0	0	0	0
Operating Income (Loss)	10,000	(275,000)	(3,336,000)	462,000
Other Income and Expenses [Abstract]
Derivative gains (losses), net	473,000	(236,000)	512,000	(721,000)
Foreign currency gains (losses), net	0	0	0	0
Other Nonoperating Income (Expense)	0	0	0	0
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	0	0	0	6,154,000
Segment Profit (Loss)	483,000	(511,000)	(2,824,000)	5,895,000
Capital Expenditures			217,000	0
Property, Plant and Equipment, Gross	44,006,000	43,693,000	44,006,000	43,693,000
Accumulated depreciation	8,614,000	2,595,000	8,614,000	2,595,000
Property, Plant and Equipment, Net In Service	35,392,000	41,098,000	35,392,000	41,098,000
Construction in Progress, Gross	0	0	0	0
Net property and equipment	35,392,000	41,098,000	35,392,000	41,098,000
Investments, at Equity, and Advances to 50% or Less Owned Companies	0	0	0	0
Inventories	12,164,000	12,822,000	12,164,000	12,822,000
Goodwill	0	0	0	0
Intangible Assets, Net	50,000	135,000	50,000	135,000
Other Current And Long-Term Assets, Excluding Cash And Near Cash Assets	10,925,000	7,154,000	10,925,000	7,154,000
Total assets	58,531,000	61,209,000	58,531,000	61,209,000
Operating Segments [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Operating Revenues	20,652,000	30,893,000	34,976,000	69,001,000
Costs and Expenses [Abstract]
Operating Expenses	18,960,000	27,566,000	33,448,000	60,643,000
Administrative and general	1,323,000	5,899,000	2,979,000	10,697,000
Depreciation and amortization	96,000	711,000	195,000	1,400,000
Total costs and expenses	20,379,000	34,176,000	36,622,000	72,740,000
Gain (Loss) on Sale of Assets and Asset Impairment Charges	0	0	1,907,000	5,000
Operating Income (Loss)	273,000	(3,283,000)	261,000	(3,734,000)
Other Income and Expenses [Abstract]
Derivative gains (losses), net	(450,000)	2,516,000	392,000	1,099,000
Foreign currency gains (losses), net	(169,000)	(84,000)	(336,000)	15,000
Other Nonoperating Income (Expense)	0	0	54,000	0
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	418,000	(371,000)	2,128,000	(726,000)
Segment Profit (Loss)	72,000	(1,222,000)	2,499,000	(3,346,000)
Capital Expenditures			357,000	6,314,000
Property, Plant and Equipment, Gross	3,989,000	22,704,000	3,989,000	22,704,000
Accumulated depreciation	531,000	3,587,000	531,000	3,587,000
Property, Plant and Equipment, Net In Service	3,458,000	19,117,000	3,458,000	19,117,000
Construction in Progress, Gross	2,087,000	2,864,000	2,087,000	2,864,000
Net property and equipment	5,545,000	21,981,000	5,545,000	21,981,000
Investments, at Equity, and Advances to 50% or Less Owned Companies	86,714,000	69,426,000	86,714,000	69,426,000
Inventories	1,219,000	5,362,000	1,219,000	5,362,000
Goodwill	0	37,138,000	0	37,138,000
Intangible Assets, Net	410,000	5,898,000	410,000	5,898,000
Other Current And Long-Term Assets, Excluding Cash And Near Cash Assets	56,591,000	83,664,000	56,591,000	83,664,000
Total assets	150,479,000	223,469,000	150,479,000	223,469,000
Operating Segments [Member] | Corporate And Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues	(605,000)	(8,000)	(1,283,000)	(195,000)
Costs and Expenses [Abstract]
Operating Expenses	(577,000)	17,000	(1,231,000)	(141,000)
Administrative and general	8,638,000	7,544,000	17,938,000	16,607,000
Depreciation and amortization	753,000	466,000	1,545,000	921,000
Total costs and expenses	8,814,000	8,027,000	18,252,000	17,387,000
Gain (Loss) on Sale of Assets and Asset Impairment Charges	0	0	141,000	0
Operating Income (Loss)	(9,419,000)	(8,035,000)	(19,394,000)	(17,582,000)
Other Income and Expenses [Abstract]
Derivative gains (losses), net	(1,023,000)	274,000	(4,161,000)	(782,000)
Foreign currency gains (losses), net	(125,000)	(511,000)	(561,000)	(63,000)
Other Nonoperating Income (Expense)	(4,000)	175,000	(69,000)	61,000
Equity in Earnings (Losses) of 50% or Less Owned Companies, Net of Tax	0	0	0	0
Capital Expenditures			1,307,000	2,781,000
Property, Plant and Equipment, Gross	29,221,000	26,471,000	29,221,000	26,471,000
Accumulated depreciation	9,709,000	10,078,000	9,709,000	10,078,000
Property, Plant and Equipment, Net In Service	19,512,000	16,393,000	19,512,000	16,393,000
Construction in Progress, Gross	1,314,000	5,672,000	1,314,000	5,672,000
Net property and equipment	20,826,000	22,065,000	20,826,000	22,065,000
Investments, at Equity, and Advances to 50% or Less Owned Companies	0	0	0	0
Inventories	0	0	0	0
Goodwill	0	0	0	0
Intangible Assets, Net	0	0	0	0
Other Current And Long-Term Assets, Excluding Cash And Near Cash Assets	22,225,000	35,858,000	22,225,000	35,858,000
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues	0	0	0	0
Intersegment Eliminations [Member] | Offshore Marine Services [Member]
Segment Reporting Information [Line Items]
Operating Revenues	(28,000)	(83,000)	52,000	52,000
Intersegment Eliminations [Member] | Inland River Services [Member]
Segment Reporting Information [Line Items]
Operating Revenues	(577,000)	0	1,231,000	0
Intersegment Eliminations [Member] | Shipping Services [Member]
Segment Reporting Information [Line Items]
Operating Revenues	0	108,000	0	108,000
Intersegment Eliminations [Member] | Ethanol and Industrial Alcohol [Member]
Segment Reporting Information [Line Items]
Operating Revenues	0	0	0	0
Intersegment Eliminations [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Operating Revenues	0	(17,000)	0	35,000
Intersegment Eliminations [Member] | Corporate And Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues	605,000	(8,000)	(1,283,000)	(195,000)
Segment Reconciling Items [Member]
Other Income and Expenses [Abstract]
Other Income (Expense) not included in Segment Profit	(1,853,000)	(8,976,000)	3,825,000	(4,830,000)
Less Equity Earnings included in Segment Profit	(7,710,000)	(295,000)	(6,841,000)	(7,956,000)
Cash And Near Cash Assets	589,198,000	533,439,000	589,198,000	533,439,000
Assets of Disposal Group, Including Discontinued Operation		$ 987,343,000		$ 987,343,000