Long Term Debt (Narrative) (Details) ¥ in Billions			1 Months Ended		3 Months Ended			6 Months Ended		12 Months Ended
	Apr. 24, 2015 JPY (¥)	Apr. 24, 2015 USD ($)	Dec. 31, 2017 USD ($)	Jun. 30, 2015 USD ($) item	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($) item	Jun. 30, 2015 USD ($) item	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($) item	Jul. 02, 2015 USD ($)	Mar. 05, 2015 item	Sep. 30, 2014 USD ($)	Aug. 31, 2014 USD ($)	Aug. 26, 2014 USD ($)
Line of Credit Facility [Line Items]
Line of credit				$ 50,000,000	$ 50,000,000			$ 50,000,000
Proceeds from borrowings of line of credit								5,000,000	$ 18,000,000
Total principal due				$ 219,270,000	219,270,000		$ 242,888,000	219,270,000		$ 242,888,000
Amount of Yen denominated foreign forward exchange contract settled		$ 4,100,000
Amount of Yen denominated interest rate swap settled		2,900,000
Loss on extinguishment of debt					(260,000)	$ (95,000)		(355,000)
Number of merged ING loan facilities | item				2
Deferred debt issuance costs reclassified from deferred charges, net				$ 3,227,000	3,227,000		$ 2,870,000	3,227,000		$ 2,870,000
Related debt paid off	¥ 2.9	24,000,000
Loss on Extinguishment of Debt					260,000	95,000		$ 355,000
Number of loan facilities | item								2
Number of shipping companies | item								2
Amount of non-amortizing guarantee under second guarantee								$ 1,000,000
Deferred gains from vessel purchase and refinancing transactions													$ 11,200,000
Number of lenders who elected to adjust definition of EBITDA | item								2
Line of credit, increase								$ 15,000,000
Number of lessors who agreed to defer the date when a more stringent leverage ratio and increased liquidity would be attained | item								2
Number of lenders that provided relief under loan to value ratio test | item								1
Number of non-performing assets identified | item							5
Number of assets held for sale impairment was recorded on | item							1
Increase in valuation allowance								$ 1,800,000
Number of held for sale assets sold prior to December 31, 2014 | item										1
Number of held for sale assets sale was finalized for | item												1
Possible amount of bank financing for construction and renovation of future corporate office								6,900,000
Incentives from the State of Louisiana								5,200,000
Unencumbered assets, fair value				65,300,000	65,300,000			65,300,000
Total amount paid off								12,500,000	$ 8,000,000
Impairment Loss					1,828,000			1,828,000
Scenario, Forecast [Member]
Line of Credit Facility [Line Items]
Amount of non-amortizing guarantee under second guarantee			$ 510,000
Subsequent Event [Member]
Line of Credit Facility [Line Items]
Line of credit facility and term loan amount											$ 85,000,000
DVB Bank SE [Member]
Line of Credit Facility [Line Items]
Deferred debt issuance costs reclassified from deferred charges, net				600,000	600,000			600,000
Loan Agreement [Member] | DVB Bank SE [Member]
Line of Credit Facility [Line Items]
Term loan facility principal amount															$ 38,500,000
Final quarterly balloon payment															$ 20,700,000
Loan Agreement [Member] | RBS Asset Finance [Member]
Line of Credit Facility [Line Items]
Term loan facility principal amount														$ 23,000,000
Senior Secured Credit Facility [Member]
Line of Credit Facility [Line Items]
Term loan facility principal amount				45,000,000	45,000,000			45,000,000
Line of credit				50,000,000	50,000,000			50,000,000
Total principal due				31,000,000	31,000,000			31,000,000
Senior Secured Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Line of credit											40,000,000
Standby Letters Of Credit [Member]
Line of Credit Facility [Line Items]
Line of credit				20,000,000	20,000,000			20,000,000
Swingline Loans [Member]
Line of Credit Facility [Line Items]
Line of credit				5,000,000	5,000,000			5,000,000
Line Of Credit Facility [Member]
Line of Credit Facility [Line Items]
Outstanding letters of credit				7,400,000	7,400,000			$ 7,400,000
Consolidated Leverage Ratio								5.00%
Minimum fixed charge coverage ratio								1.05%
Minimum Liquidity Amount								$ 20,000,000
Minimum Net Worth								$ 228,000,000
Consolidated Net Income Earned								50.00%
Percent Of The Proceeds Of Issuances Of Equity Interests Received								100.00%
Future Consolidated Leverage Ratio through the fiscal quarter ending December 31, 2015								5.00%
Future Consolidated Leverage Ratio fiscal quarter ending March 31, 2016								4.75%
Future Consolidated Leverage Ratio beginning the quarter ending June 30, 2016 through the quarter ending September 30, 2016								4.50%
Future Consolidated Leverage Ratio after September 30, 2016								4.25%
Future Minimum Fixed Charge Coverage Ratio beginning with the quarter ending September 30, 2014 through the quarter ending December 31, 2014								1.10%
Future Minimum Fixed Charge Coverage Ratio beginning with the quarter ending March 31, 2015 through the quarter ending December 31, 2015								1.15%
Future Minimum Fixed Charge Coverage Ratio beginning with the quarter ending March 31, 2016 through the quarter ending June 30, 2016								1.20%
Future Minimum Fixed Charge Coverage Ratio after June 30, 2016								1.25%
Future fixed charge coverage ratio through fiscal year 2015								1.05%
Future fixed charge coverage ratio beginning with the quarter ending March 31, 2016								1.15%
Future fixed charge coverage ratio beginning with the quarter ending June 30, 2016								1.20%
Future fixed charge coverage ratio for all periods thereafter								1.25%
Line Of Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Additional borrowing capacity											$ 1,600,000
Loan Facility A [Member]
Line of Credit Facility [Line Items]
Percentage of equity position								25.00%
Percentage of equity position guaranteed								5.00%
Amount of guarantee				$ 3,600,000	$ 3,600,000		$ 3,800,000	$ 3,600,000		$ 3,800,000
Semi-annual reduction in guarantee through December 2018								$ 165,000
Loan Facility B [Member]
Line of Credit Facility [Line Items]
Percentage of equity position								23.70%
Amount of non-amortizing guarantee								$ 1,000,000
Amount of facility covered by overall bank guarantee								$ 11,000,000
New Loan Agreement [Member] | DVB Bank SE [Member]
Line of Credit Facility [Line Items]
Term loan facility principal amount		$ 32,000,000
Fixed rate (in hundredths)		4.16%
Term for principal to be paid quarterly								5 years
Amortization period								10 years
Final quarterly balloon payment		$ 16,800,000
Handysize Vessel [Member]
Line of Credit Facility [Line Items]
Loss on extinguishment of debt						(95,000)
Number of vessels financed by merged loan facilities | item				2
Related debt paid off						13,500,000
Loss on Extinguishment of Debt						$ 95,000