Vessels (Details Textual) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2013
Property, Plant and Equipment [Line Items]
Gain (Loss) on disposition of property	$ 2,583	$ 4,234	$ 1,143
Us Flag [Member]
Property, Plant and Equipment [Line Items]
Gain (Loss) on disposition of property			$ 329
Vessels [Member] | International Crude Tankers Segment [Member] | Securities Pledged as Collateral [Member] | Very Large Crude Carrier Vessel [Member]
Property, Plant and Equipment [Line Items]
Number of Vessels		5
Vessels [Member] | International Crude Tankers Segment [Member] | Securities Pledged as Collateral [Member] | Aframaxes Vessel [Member]
Property, Plant and Equipment [Line Items]
Number of Vessels		3
Vessels [Member] | International Crude Tankers Segment [Member] | Securities Pledged as Collateral [Member] | MR [Member]
Property, Plant and Equipment [Line Items]
Number of Vessels		5
Vessels [Member] | International Crude Tankers Segment [Member] | Securities Pledged as Collateral [Member] | LR1 [Member]
Property, Plant and Equipment [Line Items]
Number of Vessels		2