Significant Operations (Reconciliation From Segment Totals To Consolidated) (Details) (USD $) In Thousands, unless otherwise specified	1 Months Ended	3 Months Ended								12 Months Ended
	Mar. 31, 2012	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of profit (loss) from segments to consolidated [Abstract]
Total Gross Voyage Profit for Reportable Segments										$ 55,168	$ 54,773	$ 70,704
Unallocated Amounts [Abstract]
Vessel and Other Depreciation										(24,432)	(24,398)	(25,388)
Administrative and General Expenses										(22,734)	(23,244)	(20,961)
(Loss)/Gain on Sale of Other Assets	3,800									(16)	16,625
Loss (Income) of Unconsolidated Entities										1,661	215	410
Gain on Dry Bulk Transaction												18,844
Operating Income		5,978	1,959	1,404	306	10,128	4,013	3,518	6,312	9,647	23,971	43,609
Interest Expense										(9,504)	(10,409)	(10,361)
Derivative Loss										(438)	(485)	(101)
Gain (Loss) on Sale of Investment											580	(747)
Investment Income										114	470	637
Other Income from Vessel Financing										2,122	2,387	2,653
Foreign Exchange Gain (Loss)										5,914	5,506	(3,051)
Income Before Income Taxes										7,855	22,020	32,639
Reconciliation of assets from segments to consolidated [Abstract]
Total Assets for Reportable Segments		507,957				492,797				507,957	492,797	529,151
Unallocated Amounts [Abstract]
Current Assets		87,104				89,244				87,104	89,244
Investment in Unconsolidated Entities		14,818				12,676				14,818	12,676
Due from Related Parties		1,699				1,709				1,699	1,709
Other Assets		7,383				5,509				7,383	5,509
Goodwill		2,735				2,700				2,735	2,700
Deferred Tax Asset		7,020								7,020
Notes Receivable		27,659				33,381				27,659	33,381
TOTAL ASSETS		$ 656,375				$ 638,016				$ 656,375	$ 638,016