SIGNIFICANT ACCOUNTING POLICIES - RECOGNITION OF REVENUES AND EXPENES (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Total	$ 406.6	$ 392.7	$ 785.9	$ 762.7
Total	150.5	119.8	282.6	224.2
Ocean Transportation
Ocean transportation services	401.2	388.2	775.9	753.2
Terminal and other related services	0.5	0.8	1.3	1.6
Fuel sales	3.1	2.0	5.2	4.5
Ship management services	1.8	1.7	3.5	3.4
Total	406.6	392.7	$ 785.9	$ 762.7
Percentage of ocean transportation revenues and fuel sales denominated in foreign currency			3.00%	3.00%
Logistics
Transportation brokerage and freight forwarding services	136.4	106.9	$ 255.6	$ 199.2
Warehouse and distribution services	7.8	7.3	15.2	14.5
Supply chain management and other services	6.3	5.6	11.8	10.5
Total	$ 150.5	$ 119.8	$ 282.6	$ 224.2
Percentage of transportation brokerage and freight forwarding services revenue denominated in forgeign currency			3.00%	3.00%