VESSELS, OTHER PROPERTY AND DEFERRED DRYDOCK (Drydocking Activity) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Beginning Balance	$ 31,172	$ 58,166	$ 33,087
Additions	8,787	2,626	45,046
Sub-total	39,959	60,792	78,133
Drydock amortization	(16,045)	(25,747)	(19,967)
Impairments	0	(3,873)	0
Ending Balance	$ 23,914	$ 31,172	$ 58,166