Leases (Details Textual) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013
Estimated For Lease Termination Costs	$ 189,753
Charters In [Member]
Commitments to charter in vessels, Number of Units	25
Bareboat Charters In [Member]
Commitments to charter in vessels, Number of Units	12
Time Charters In [Member]
Commitments to charter in vessels, Number of Units	13
Charter Out [Member] | Contract Of Affreightmen [Member]
Operating Leases, Future Minimum Payments Receivable, Current	16,740
Operating Leases, Future Minimum Payments Receivable, in Two Years	21,375
Operating Leases, Future Minimum Payments Receivable, in Three Years	21,699
Operating Leases, Future Minimum Payments Receivable, in Four Years	22,023
Operating Leases, Future Minimum Payments Receivable, in Five Years	22,347
Operating Leases, Future Minimum Payments Receivable, Thereafter	52,085
Office Space [Member]
Leasehold Improvements, Gross	$ 1,638