Commitments And Contingencies (Details) $ in Millions	9 Months Ended
	Sep. 30, 2015 USD ($) item	Jan. 06, 2015 USD ($)	Sep. 30, 2014 USD ($)	Jun. 26, 2014 USD ($) item
Commitments And Contingencies [Line Items]
Deposit and interest collected		$ 4.2
Deposit reclassified to current receivable			$ 3.9
Interest accrued on receivable from customer			$ 0.3
Number of vessels held under operating lease contracts | item	3
If Defaulted on any of Operating Lease Agreements [Member]
Commitments And Contingencies [Line Items]
Stipulated loss value if forced to buy back vessels	$ 75.1
Jones Act [Member] | Molten Sulphur Carrier [Member]
Commitments And Contingencies [Line Items]
Number of vessels held under operating lease contracts | item	1
PCTC [Member] | Pure Car Truck Carriers [Member]
Commitments And Contingencies [Line Items]
Number of vessels held under operating lease contracts | item	2
U.S. Customs And Border Protection [Member]
Commitments And Contingencies [Line Items]
Number of affiliates that allegedly failed to properly report the importation of spare parts consumed by vessels | item				2
Amount of proposed duty				$ 1.4
Amount of proposed penalty on assessment				$ 5.7