Long-Term Debt (Schedule of Long-Term Debt) (Details) (USD $)						0 Months Ended	1 Months Ended				9 Months Ended								9 Months Ended						9 Months Ended	12 Months Ended	9 Months Ended				9 Months Ended				9 Months Ended		9 Months Ended								9 Months Ended					1 Months Ended	6 Months Ended
	Sep. 30, 2013	Sep. 24, 2013	Dec. 31, 2012	Sep. 30, 2013 Notes Payable - Variable Rate 2015 [Member]	Nov. 30, 2012 Notes Payable - Variable Rate 2017 A [Member]	Jun. 20, 2011 Notes Payable - Variable Rate 2018, Tranche A [Member]	Jan. 24, 2012 Notes Payable - Variable Rate 2018, Tranche B [Member]	Nov. 30, 2011 Notes Payable - Variable Rate 2018, Tranche B [Member]	Jun. 20, 2011 Notes Payable - Variable Rate 2018, Tranche B [Member]	Sep. 30, 2013 Notes Payable - Variable Rate 2020 [Member]	Sep. 30, 2013 Notes Payable - Variable Rate 2018 E [Member]		Dec. 31, 2012 Notes Payable - Variable Rate 2018 E [Member]		Sep. 30, 2013 Senior Secured Credit Facility [Member] Notes Payable - Variable Rate 2015 [Member]		Dec. 31, 2012 Senior Secured Credit Facility [Member] Notes Payable - Variable Rate 2015 [Member]		Sep. 30, 2013 Senior Secured Credit Facility [Member] Notes Payable - Variable Rate 2017 A [Member]	Dec. 31, 2012 Senior Secured Credit Facility [Member] Notes Payable - Variable Rate 2017 A [Member]	Sep. 30, 2013 Senior Secured Credit Facility [Member] Notes Payable - Variable Rate 2017 B [Member]		Dec. 31, 2012 Senior Secured Credit Facility [Member] Notes Payable - Variable Rate 2017 B [Member]		Sep. 30, 2013 Senior Secured Credit Facility [Member] Notes Payable - Variable Rate 2018, Tranche A [Member]	Dec. 31, 2012 Senior Secured Credit Facility [Member] Notes Payable - Variable Rate 2018, Tranche A [Member]	Sep. 30, 2013 Senior Secured Credit Facility [Member] Notes Payable - Variable Rate 2018, Tranche B [Member]		Dec. 31, 2012 Senior Secured Credit Facility [Member] Notes Payable - Variable Rate 2018, Tranche B [Member]		Sep. 30, 2013 Senior Secured Credit Facility [Member] Notes Payable - Variable Rate 2018 C [Member]		Dec. 31, 2012 Senior Secured Credit Facility [Member] Notes Payable - Variable Rate 2018 C [Member]		Sep. 30, 2013 Senior Secured Credit Facility [Member] Notes Payable - Variable Rate 2018 D [Member]	Dec. 31, 2012 Senior Secured Credit Facility [Member] Notes Payable - Variable Rate 2018 D [Member]	Sep. 30, 2013 Senior Secured Credit Facility [Member] Notes Payable - Variable Rate 2020 [Member]		Dec. 31, 2012 Senior Secured Credit Facility [Member] Notes Payable - Variable Rate 2020 [Member]		Sep. 30, 2013 Old Line Of Credit Facility [Member]		Dec. 31, 2012 Old Line Of Credit Facility [Member]		Sep. 30, 2013 Secured Line Of Credit - New [Member]		Sep. 24, 2013 Senior Secured Credit Facility [Member] item	Sep. 24, 2013 Standby Letters of Credit [Member]	Sep. 24, 2013 Swingline Loans [Member]	Jan. 31, 2013 Revolving Credit Facility [Member]	Jun. 30, 2013 Revolving Credit Facility [Member]	Jun. 28, 2013 Revolving Credit Facility [Member]	Jun. 27, 2013 Revolving Credit Facility [Member]	Dec. 31, 2012 Revolving Credit Facility [Member]	Nov. 28, 2012 Revolving Credit Facility [Member]	Nov. 27, 2012 Revolving Credit Facility [Member]	Jun. 20, 2011 ING Bank [Member] item	Nov. 30, 2012 UOS [Member] Notes Payable - Variable Rate 2017 A [Member]
Debt Instrument [Line Items]
Interest Rate											3.7496%	[1]	0.00%	[1]	0.00%	[2]	2.06%	[2]	2.5326%	2.559%	0.00%	[1],[3]	2.709%	[1],[3]			2.7525%	[4]	2.809%	[4]	2.7647%	[4]	2.8158%	[4]	2.9181%	2.981%	3.715%	[5]	1.8314%	[5]	0.00%	[6]	3.95%	[6]	3.68%	[1]
Interest Rate, minimum																									2.76%	2.81%
Interest Rate, maximum																									(2.77%)	2.85%
Maturity Date											2018	[1]							2017						2018		2018	[4]			2018	[4]			2018		2020	[5]							2018	[1]
Total Principal Due	$ 205,282,000		$ 237,630,000								$ 45,000,000	[1]					$ 12,666,000	[2]	$ 11,942,000	$ 13,436,000			$ 30,000,000	[1],[3]	$ 46,000,000	$ 48,760,000	$ 16,320,000	[4]	$ 18,896,000	[4]	$ 16,965,000	[4]	$ 17,908,000	[4]	$ 13,490,000	$ 15,620,000	$ 34,565,000	[5]	$ 42,089,000	[5]			$ 38,255,000	[6]	$ 21,000,000	[1]
Less Current Maturities	(19,164,000)		(26,040,000)
Long-Term Debt, Noncurrent	186,118,000		211,590,000
Interest rate swap , fixed interest rate (in hundredths)				4.41%						2.065%
Effective, swaption interest rate (in hundredths)										3.715%
Early pre-payment amount				13,300,000																																											25,500,000
Term of financing agreement					5 years																																																				7 years
Business acquisition interest in acquiree						100.00%
Number of tranches																																																									2
Line of credit		50,000,000																																														20,000,000	5,000,000
Number of lenders																																															4
Lender commitments, minimum																																															15,000,000
Lender commitments, maximum																																															30,000,000
Maximum borrowing capacity									23,300,000																																						45,000,000					35,000,000	30,000,000		42,000,000	30,000,000		30,000,000
Proceeds from borrowings of line of credit						24,100,000	12,700,000	6,100,000																																											31,000,000
Repayments of long term lines of credit																																																		12,000,000
Loans pledged as collateral																																																			$ 3,700,000
Long-term debt weighted average interest rate																																																			3.3275%			3.2645%

[1] On September 24, 2013, we entered into a senior secured Credit Facility. The Credit Facility matures on September 24, 2018 and includes a term loan facility in the principal amount of $45 million and a LOC in the principal amount of $50 million. The LOC facility includes a $20 million sublimit for the issuance of standby letters of credit and a $5 million sublimit for swingline loans. As of September 24, 2013, the Credit Facility had four lenders, each with commitments ranging from $15 million to $30 million.Effective November 28, 2012, our revolving credit facility was increased from $30 million to $42 million to provide additional funds for working capital purposes. This revolver was considered fully drawn at December 31, 2012 and the $12 million increase was fully repaid in January 2013. On June 28, 2013 our revolving facility availability was increased from $30 million to $35 million for working capital purposes. The amount drawn at June 30, 2013 was $31.0 million, with $3.7 million used as collateral for various letters of credit. The net weighted average interest rate on all of our long-term debt after consideration of the effect of our interest rate swaps at June 30, 2013 and December 31, 2012 was 3.3275% and 3.2645%, respectively. This unsecured line of credit agreement was paid off with execution of the new secured credit facility on September 24, 2013.

[2] We had an interest rate swap agreement in place to fix the interest rate on our variable rate note payable expiring in 2015 at 4.41%. Upon early repayment of approximately $13.3 million to close this credit facility, the interest rate swap was settled and terminated.

[3] We entered into a variable rate financing agreement with Capital One N.A. on November 30, 2012 for a five year facility totaling $30 million to finance a portion of the acquisition of UOS. This facility was fully drawn prior to the end of 2012. Upon execution of the new US Senior Credit Facility, this credit facility was paid off in full. The early pre-payment amount was approximately $25.5 million.

[4] We entered into a variable rate financing agreement with ING Bank N.V., London branch on June 20, 2011 for a seven year facility to finance the acquisition of a Cape Size vessel and a Handymax Bulk Carrier Newbuilding, both of which we acquired a 100% interest in as a result of our acquisition of Dry Bulk. Pursuant to the terms of the facility, the lender agreed to provide a secured term loan facility divided into two tranches: Tranche A, fully drawn on June 20, 2011 in the amount of $24.1 million, and Tranche B, providing up to $23.3 million of additional credit. Under Tranche B, we drew $6.1 million in November 2011 and $12.7 million on January 24, 2012.

[5] We have an interest rate swap agreement in place to fix the interest rate on our variable rate note payable expiring in 2020 at 2.065%. After applicable margin adjustments, the effective interest rate on this note payable is fixed at 3.715%. The swap agreement is for the same term as the associated note payable.On September 24, 2013, we entered into a senior secured Credit Facility. The Credit Facility matures on September 24, 2018 and includes a term loan facility in the principal amount of $45 million and a LOC in the principal amount of $50 million. The LOC facility includes a $20 million sublimit for the issuance of standby letters of credit and a $5 million sublimit for swingline loans. As of September 24, 2013, the Credit Facility had four lenders, each with commitments ranging from $15 million to $30 million.

[6] Effective November 28, 2012, our revolving credit facility was increased from $30 million to $42 million to provide additional funds for working capital purposes. This revolver was considered fully drawn at December 31, 2012 and the $12 million increase was fully repaid in January 2013. On June 28, 2013 our revolving facility availability was increased from $30 million to $35 million for working capital purposes. The amount drawn at June 30, 2013 was $31.0 million, with $3.7 million used as collateral for various letters of credit. The net weighted average interest rate on all of our long-term debt after consideration of the effect of our interest rate swaps at June 30, 2013 and December 31, 2012 was 3.3275% and 3.2645%, respectively. This unsecured line of credit agreement was paid off with execution of the new secured credit facility on September 24, 2013.