PROPERTY AND EQUIPMENT (Details) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2018 USD ($) item	Dec. 31, 2017 USD ($)
Property and equipment
Cost	$ 2,617.4	$ 2,444.2
Less: Accumulated Depreciation	(1,310.3)	(1,278.5)
Property and equipment, net	1,307.1	1,165.7
Vessels
Property and equipment
Cost	1,442.1	1,433.6
Containers and equipment
Property and equipment
Cost	530.2	543.0
Terminal facilities and other property
Property and equipment
Cost	65.9	64.8
Vessel construction in progress
Property and equipment
Cost	543.4	376.6
Capitalized Interest
Interest Costs Capitalized	$ 18.6	10.4
Number of vesels under agreements for contstruction | item	4
Other construction in progress
Property and equipment
Cost	$ 35.8	$ 26.2