SIGNIFICANT ACCOUNTING POLICIES - PROPERTY AND EQUIPMENT (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) item	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Impairment of Investment
Impairment charges related to investment in Terminal joint venture | $	$ 0.0	$ 0.0	$ 0.0
Dry-docking
Number of dry-docking inspections to be made within a specified period	2
Period within which number of specified dry-docking inspections to be made	5 years
Number of non-U.S. flag vessels in operations	4
Number of non-U.S. flag vessels owned	1
Number of non-U.S. flag vessels under bareboat charter	1
Number of non-U.S. flag vessels under time charter	2
Dry-dock inspections interval, minimum	2 years
Dry-dock inspections interval, maximum	5 years
Vessels | Maximum
Depreciation
Useful life	40 years
Machinery And Equipment | Maximum
Depreciation
Useful life	20 years
Terminal Facilities | Maximum
Depreciation
Useful life	35 years
Operating costs
Long-lived Assets
Impairment charges related to long-lived assets | $	$ 2.1	$ 0.0	$ 0.0