Represents minimum period for dry-docking.

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Estimated fair value of a long lived asset which was recorded an impairment charge during the period.

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Represents the number of dry-docking inspections to be made within a specified period.

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Represents the period within which number of specified dry-docking inspections to be made.

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The aggregate amount of write-downs for impairments recognized during the period for long lived assets held for use (including those held for disposal by means other than sale).

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Amount of interest capitalized during the period.

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Amount before tax of other than temporary impairment (OTTI) on investment in available-for-sale debt security, recognized in other comprehensive loss, attributable to parent entity.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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SIGNIFICANT ACCOUNTING POLICIES - PROPERTY AND EQUIPMENT AND OTHER (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) item	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Impairment of Investment
Impairment charges related to investment in Terminal joint venture	$ 0.0	$ 0.0	$ 0.0
Long-lived Assets
Estimated fair value of inactive vessels		0.0
Capitalized Interest
Interest Costs Capitalized	$ 7.5	2.1	0.4
Dry-docking
Number of dry-docking inspections to be made within a specified period \| item	2
Period within which number of specified dry-docking inspections to be made	5 years
Dry-dock inspections interval, minimum	36 months
Vessels
Depreciation
Useful life	40 years
Machinery And Equipment
Depreciation
Useful life	30 years
Terminal Facilities
Depreciation
Useful life	35 years
Operating costs
Long-lived Assets
Impairment charges related to long-lived assets		$ 0.0	$ 2.1	$ 0.0