Operating Segments (Details) (USD $) In Thousands, unless otherwise specified	1 Months Ended	3 Months Ended				9 Months Ended
	Mar. 31, 2012	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Segment Reporting Information [Line Items]
Number of operating segments						5
Segment Profit and Loss [Abstract]
Revenue from External Customers		$ 61,162		$ 67,087		$ 186,686		$ 201,382
Intersegment Revenues (Eliminated)		(4,594)		(4,664)		(14,905)		(13,995)
Intersegment Expenses (Eliminated)		4,594		4,664		14,905		13,995
Voyage Expenses (Income)		45,394		46,911		143,246		147,715
Gross Voyage Profit *		15,768	[1]	20,176	[1]	43,440	[1]	53,667	[1]
Gross Voyage Profit percentage (in hundredths)		26.00%		30.00%		23.00%		27.00%
Less [Abstract]
Vessel Depreciation		6,109		6,775		18,189		18,244
Gross Profit (Loss)		9,659	[1]	13,401	[1]	25,251	[1]	35,423	[1]
Interest Expense		2,144		2,850		7,152		7,470
Segment Profit (Loss)		7,515		10,551		18,099		27,953
Reconciliation of Profit (Loss) from Segments to Consolidated [Abstract]
Segment Profit (Loss)		7,515		10,551		18,099		27,953
Unallocated Amounts [Abstract]
Administrative and General Expenses		(5,643)		(4,769)		(15,871)		(16,053)
Gain (Loss) on Sale/Purchase of Other Assets	3,800	(3)		0		4,463		0
Derivative Loss		(129)		(124)		(97)		(109)
Gain on Sale of Investment		0		67		66		181
Other Income from Vessel Financing		588		654		1,815		2,014
Investment Income		117		137		391		522
Foreign Exchange Gain (Loss)		(1,143)		(2,664)		771		(3,075)
Gain on Dry Bulk Transaction		0		0		0		18,844
Income Before Provision for Income Taxes and Equity in Net (Loss) Income of Unconsolidated Entities		1,302		3,852		9,637		30,277
Time Charter Contracts - U.S. Flag [Member]
Segment Profit and Loss [Abstract]
Revenue from External Customers		36,121		38,069		109,638		116,381
Intersegment Revenues (Eliminated)		0		0		0		0
Intersegment Expenses (Eliminated)		0		0		0		0
Voyage Expenses (Income)		27,003		27,233		85,965		87,190
Gross Voyage Profit *		9,118	[1]	10,836	[1]	23,673	[1]	29,191	[1]
Gross Voyage Profit percentage (in hundredths)		25.00%		28.00%		22.00%		25.00%
Less [Abstract]
Vessel Depreciation		2,301		2,707		7,174		7,712
Gross Profit (Loss)		6,817	[1]	8,129	[1]	16,499	[1]	21,479	[1]
Interest Expense		557		914		1,865		2,267
Segment Profit (Loss)		6,260		7,215		14,634		19,212
Reconciliation of Profit (Loss) from Segments to Consolidated [Abstract]
Segment Profit (Loss)		6,260		7,215		14,634		19,212
Time Charter Contracts - International Flag [Member]
Segment Profit and Loss [Abstract]
Revenue from External Customers		12,400		14,609		37,626		41,777
Intersegment Revenues (Eliminated)		0		0		0		0
Intersegment Expenses (Eliminated)		0		0		0		0
Voyage Expenses (Income)		8,221		7,173		22,608		22,516
Gross Voyage Profit *		4,179	[1]	7,436	[1]	15,018	[1]	19,261	[1]
Gross Voyage Profit percentage (in hundredths)		34.00%		51.00%		40.00%		46.00%
Less [Abstract]
Vessel Depreciation		2,789		3,151		8,582		7,837
Gross Profit (Loss)		1,390	[1]	4,285	[1]	6,436	[1]	11,424	[1]
Interest Expense		1,208		1,688		4,037		4,326
Segment Profit (Loss)		182		2,597		2,399		7,098
Reconciliation of Profit (Loss) from Segments to Consolidated [Abstract]
Segment Profit (Loss)		182		2,597		2,399		7,098
Contracts of Affreightment [Member]
Segment Profit and Loss [Abstract]
Revenue from External Customers		4,796		4,766		12,397		13,497
Intersegment Revenues (Eliminated)		0		0		0		0
Intersegment Expenses (Eliminated)		0		0		0		0
Voyage Expenses (Income)		3,518		4,685		11,828		13,597
Gross Voyage Profit *		1,278	[1]	81	[1]	569	[1]	(100)	[1]
Gross Voyage Profit percentage (in hundredths)		27.00%		2.00%		5.00%		(1.00%)
Less [Abstract]
Vessel Depreciation		304		0		304		0
Gross Profit (Loss)		974	[1]	81	[1]	265	[1]	(100)	[1]
Interest Expense		111		0		370		0
Segment Profit (Loss)		863		81		(105)		(100)
Reconciliation of Profit (Loss) from Segments to Consolidated [Abstract]
Segment Profit (Loss)		863		81		(105)		(100)
Rail-Ferry Service [Member]
Segment Profit and Loss [Abstract]
Revenue from External Customers		7,513		9,121		26,108		27,894
Intersegment Revenues (Eliminated)		0		0		0		0
Intersegment Expenses (Eliminated)		0		0		0		0
Voyage Expenses (Income)		6,611		7,685		22,983		23,973
Gross Voyage Profit *		902	[1]	1,436	[1]	3,125	[1]	3,921	[1]
Gross Voyage Profit percentage (in hundredths)		12.00%		16.00%		12.00%		14.00%
Less [Abstract]
Vessel Depreciation		715		915		2,129		2,687
Gross Profit (Loss)		187	[1]	521	[1]	996	[1]	1,234	[1]
Interest Expense		158		155		540		541
Segment Profit (Loss)		29		366		456		693
Reconciliation of Profit (Loss) from Segments to Consolidated [Abstract]
Segment Profit (Loss)		29		366		456		693
Other [Member]
Segment Profit and Loss [Abstract]
Revenue from External Customers		332		522		917		1,833
Intersegment Revenues (Eliminated)		(4,594)		(4,664)		(14,905)		(13,995)
Intersegment Expenses (Eliminated)		4,594		4,664		14,905		13,995
Voyage Expenses (Income)		41		135		(138)		439
Gross Voyage Profit *		291	[1]	387	[1]	1,055	[1]	1,394	[1]
Gross Voyage Profit percentage (in hundredths)		88.00%		74.00%		115.00%		76.00%
Less [Abstract]
Vessel Depreciation		0		2		0		8
Gross Profit (Loss)		291	[1]	385	[1]	1,055	[1]	1,386	[1]
Interest Expense		110		93		340		336
Segment Profit (Loss)		181		292		715		1,050
Reconciliation of Profit (Loss) from Segments to Consolidated [Abstract]
Segment Profit (Loss)		$ 181		$ 292		$ 715		$ 1,050

[1] Information used by Chief Decision Makers; see "Management's Discussion and Analysis of Financial Condition and Results of Operation- Non-GAAP Financial Measures."