CONTINGENCIES (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)	Mar. 22, 2014 TankBarge Vessel
Guaranties [Abstract]
Issued guaranties	$ 20,085
Maximum [Member]
Guaranties [Abstract]
Guarantor obligations, expiration period	3 years
Performance Bonds [Member]
Guaranties [Abstract]
Issued guaranties	$ 9,207
Collision with M/S Summer Wind [Member]
Loss Contingency [Abstract]
Number of vessels involved in collision | Vessel		2
Number of vessels damaged in collision resulting in fuel oil discharge | TankBarge		1
Letters of Credit [Member]
Guaranties [Abstract]
Issued guaranties	$ 10,878